Black eared opossum

Black eared opossum DEFAULT

Geographic Range

Common opossums (Didelphis marsupialis) are found throughout much of Central and South America. The range of this species is limited by high elevations and dry environments. These animals are found native to the following countries: Argentina, Belize, Bolivia, Brazil, Columbia, Costa Rica, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname, Trinidad, Tobago and Venezuela. In recent history, these animals have also been introduced to a variety of islands. (Brito, et al., 2008; Cerqueira and Tribe, 2008)

Habitat

Common opossums are found in a variety of habitats throughout Central and South America. These animals are considered habitat generalists and are even tolerant of anthropogenically altered environments. They are not found in areas of exceptionally high elevation or extremely dry habitats, although they are found in montane environments in Costa Rica and may survive in areas with a wide range of precipitation. It has been suggested that common opossums may be the most tolerant and adaptable Neotropical mammal. Their preferred habitats include tropical, subtropical, old growth, evergreen and gallery forests in lowland regions below about 2,000 meters on average. These animals also frequent urban environments such as near human dwellings and garbage dumps, as well as agricultural lands including pastures and cacao, coffee and citrus plantations. Common opossums may be found on the ground or in large trees, although they are more terrestrial than some members of their genus. (Adler, et al., 2012; Brito, et al., 2008; Cerqueira and Tribe, 2008; Estrada, et al., 1994; Medellin, 1994; Reid, 2009; Tyndale-Biscoe, 1973)

Physical Description

Common opossums are robust marsupials. The fur on their body is thick with long guard hairs, leading these animals to appear somewhat disheveled. Their dorsal pelage is often dark, typically blackish or grayish, but in rare instances they may appear whitish. In comparison, their ventral fur is yellow or cream. These animals have primarily whitish fur on their faces and a dark stripe extending to the crown of their heads, with a black ring around both eyes. Their ears are large and all black. Common opossums have sharp claws, long whiskers and a primarily naked prehensile tail that is slightly longer than their body. These animals are sexually dimorphic; males trapped in French Guiana averaged 1.2 kg, whereas females averaged 1.03 kg. These values may be low; other sources suggest that their body weights range between 4 to 6 kg. In general, adult males have longer canines than adult females. Common opossums typically have a total body length of 371 mm (ranging from 265 to 430 mm), including a tail length of 395 mm. (Castillo-Flores and Calvo-Irabien, 2003; Reid, 2009; Richard-Hansen, et al., 1999; Shripat, 2011; Tyndale-Biscoe and Renfree, 1987)

Reproduction

Common opossums show a polygynous mating system, in which males compete for reproductive females. These animals are almost exclusively solitary, but come together seasonally for breeding. Didelphids do not exhibit courtship rituals and do not pair bond. Females experience a 25 to 32 day estrous cycle. When resources are limited or unavailable these animals may choose not to mate. (Fernandes, et al., 2010; Julien-Laferriere and Atramentowicz, 1990; O'Connell, 2006; Shripat, 2011; Sunquist, et al., 1987)

Breeding seasons and the number of annual litters varies based on latitude. Breeding seasons can vary from one long season from January to September or several shorter seasons annually. These seasons may be correlated with seasonal precipitation. Female common opossums begin breeding when they are 6 to 7 months old. Gestation typically lasts 13 to 15 days, after which 2 to 20 altricial young are born, interestingly; animals living closer to the equator tend to have smaller litters. At birth, their young are tiny; they are usually about 1 cm long and weigh about 0.13 grams. Although they are extremely under-developed, newborn common opossums have well-developed claws on their front legs that help them climb to their mother’s pouch. Once inside the pouch, their young remain attached to the mammae for about 50 days. Young are weaned and independent when they are 90 to 125 days old, often when fruit is plentiful. (Brito, et al., 2008; Cabello, 2006; Gustavo, et al., 1990; Julien-Laferriere and Atramentowicz, 1990; O'Connell, 2006; Shripat, 2011; Tyndale-Biscoe and Mackenzie, 1976; Tyndale-Biscoe and Renfree, 1987; Tyndale-Biscoe, 1973; Tyndale-Biscoe, 2005)

Common opossums offer very little parental care. Males have no involvement in raising their offspring and females invest a minimal effort. When their tiny offspring are born, they begin a harrowing journey to their mother’s pouch; many of the young will not survive. Female common opossums typically only have 9 teats available for nursing, so they often have more offspring than they can accommodate. However, they have a fairly low mortality rate once they are safely inside the pouch and nursing. The young may begin leaving the pouch when they are about 70 days old, at which time they may begin riding on their mother’s back while she forages. The young become independent when they are weaned between 90 and 125 days old. Interestingly, a study in Venezuela determined that females with ample resources are more likely to have mostly male offspring, whereas, when resources become limited they typically have a greater number of females in their litters. (Austad and Sunquist, 1987; Julien-Laferriere and Atramentowicz, 1990; Shripat, 2011; Tyndale-Biscoe and Mackenzie, 1976; Tyndale-Biscoe and Renfree, 1987)

  • altricial
  • female parental care
  • pre-hatching/birth
    • provisioning
    • protecting
  • pre-weaning/fledging
    • provisioning
    • protecting
  • pre-independence
    • provisioning
    • protecting

Lifespan/Longevity

Common opossums are very short lived; they typically live fewer than 2 years. In a long term study of these animals, the oldest individual lived to be 20 months old, in another study; the oldest individual lived to be 11 months old. These animals experience their greatest mortality rate prior to maturity and while lactating. Common opossums are frequent victims of collisions with cars. (Kajin, et al., 2008; Pinowski, 2005; Reid, 2009; Sunquist, et al., 1987)

Behavior

Common opossums are solitary and nocturnal. They begin their daily activities about an hour before sunset; however, their activity level peaks from 11 pm to 3 am. These animals are primarily terrestrial but spend a significant amount of time in trees, although other members of their genus are much more arboreal. During daylight hours, common opossums stay inside their burrows. Burrow locations vary and include tree cavities, underground, in palm or fig trees, in the tree canopy or in the abandoned nests of other species. These animals do not maintain a burrow for very long, males remain in the same den for about 1.5 days on average and females remain in the same den for about 5.1 days. (Adler, et al., 2012; Brito, et al., 2008; Julien-Laferriere and Atramentowicz, 1990; Reid, 2009; Shripat, 2011; Sunquist, et al., 1987; Vaughan, et al., 1999)

Home Range

Male common opossums maintain a much larger home range than their female counterparts. Females average 16.3 hectares (+/- 8.2 ha), whereas males average a home range of 123 hectares (+/- 60.8 ha). Male home ranges overlap; generally there is about one individual per hectare. (Brito, et al., 2008; Sunquist, et al., 1987)

Communication and Perception

Common opossums use a variety of perception channels. Their auditory ability develops relatively late in life, young do not fully develop their auditory capabilities until they are about 80 days old. Common opossums may communicate vocally, specifically when they are engaged in an aggressive encounter. In such circumstances, these animals may hiss, growl or screech. Common opossums also perform a variety of visual displays when engaged in an aggressive interaction including rocking from side to side, drooling, baring their teeth, and in the case of an extreme threat, these animal have also been known to enter a catatonic state, commonly known as ‘playing opossum’. Olfaction is also used to communicate; common opossums may produce a secretion from their anal gland or spray urine and feces when a threat is perceived. Their vision is acute and is likely on par with the visual abilities of cats; however, their visual acuity is limited when compared to some primates. (Ehret, 1983; Oswaldo-Cruz, et al., 1979; Reid, 2009; Shripat, 2011; Volchan, et al., 2004)

Food Habits

Common opossums have a very broad diet. Their feeding habits are often referred to as opportunistic omnivory. Their diet includes invertebrates, vertebrates, leaves, fruits, nectar and carrion. Common opossums may alter their diet seasonally, during the dry season mammals and birds are more likely consumed, whereas during the wet season they rely more heavily on fruits, snakes and toads. Regardless of the season, invertebrates are a primary staple of their diet including earthworms, beetles and grasshoppers. After weaning, their diet remains fairly constant throughout their life, although older animals tend to consume vertebrates more frequently. Common opossums eat a variety of vertebrates including birds such as lance-tailed manikins, amphibians such as cane toads, reptiles such as Venezuelan rattlesnakes and a variety of small mammals. Interestingly, their ability to consume rattlesnakes is facilitated by their apparent immunity to the venom of many members of family Vipiridae. (Almeida-Santos, et al., 2000; Cerqueira and Tribe, 2008; Cordero and Nicolas, 1987; Garrett and Boyer, 1993; Reid, 2009; Reidy, 2009)

  • birds
  • mammals
  • amphibians
  • reptiles
  • carrion
  • insects
  • terrestrial worms

Predation

Given their abundance, common opossums are likely prey for a variety of large mammals throughout Central and South America. Their known predators include ocelots, jaguarundis and harpy eagles. When a threat is detected, common opossums may choose to run or climb a tree to evade predators. Less frequently, these animals may enter a catatonic state, commonly known as 'playing opossum'. This death feigning behavior may last as little as 1 minute or as long as 6 hours. (Gustavo, et al., 1990; Rotenberg, et al., 2012; Shripat, 2011)

Ecosystem Roles

Common opossums carry a variety of parasites; some reports claim they may carry up to 46 species of internal and external parasites. Most notably, Trypanosoma cruzi may be found in their anal glands. They also carry a variety of cestodes, nematodes and acanthocephala in their large and small intestines. Common opossums are also important seed dispersers. They move some seeds due to ingestion after eating fruits, such as for Cecropia. However, their shaggy fur also causes them to transport diasporas from Pavonia schiedeana and Desmodium incanum. These plants are anthropogenic herbs and have been introduced to the forest understory partially via the fur of animals. (Castillo-Flores and Calvo-Irabien, 2003; Cerqueira and Tribe, 2008; Deane, et al., 1984; Jimenez, et al., 2011; Medellin, 1994)

Commensal/Parasitic Species
  • Cestode: Mathevotaenia bivittata
  • Nematode: Aspidodera raillieti; Capillaria eberthi; Cruzia tentaculata; Moennigia; Spirura guianensis; Travassostrongylus paraquintos; Trichuris reesali; Viannaia viannai
  • Acanthocephala: Oligacanthorhynchus microcephala; Oncicola campanulata

Economic Importance for Humans: Positive

Common opossums are often hunted by humans. They are killed for sport and food and are even part of the illegal wild game trade. Some cultures believe that the fat of common opossums can be used to treat a variety of ailments including stomach aches, rheumatism, diarrhea, inflammation, skin infections, labor pains, asthma, headaches, toothaches, ear aches and sore throats. (Alves and Rosa, 2006; Alves and Rosa, 2007; Brito, et al., 2008; Junior, et al., 2010)

Economic Importance for Humans: Negative

Common opossums are known to transmit diseases which impact human populations, such as Chagas disease and leishmaniansis. These animals may also be considered pests due to their aptitude for killing bats caught in research mist nets and their proclivity for poultry. (Brito, et al., 2008; Cabello, 2006; Deane, et al., 1984; Reid, 2009)

Conservation Status

Common opossums are currently listed as a species of least concern according to the IUCN Red List of Threatened Species. These animals are found throughout much of Central and South America and likely have a very large population size. Their ability to live in anthropogenically disturbed environments facilities this species broad success. (Brito, et al., 2008)

South American didelphids are commonly grouped into either ‘white-eared’ or ‘black-eared opossums’. Common opossums (Didelphis marsupialis) are included in the ‘black-eared opossum’ group, along with big-eared opossums (Didelphis aurita). (Cerqueira and Tribe, 2008)

Contributors

Leila Siciliano Martina (author), Animal Diversity Web Staff.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carrion

flesh of dead animals.

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

polygynous

having more than one female as a mate at one time

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Adler, G., A. Carvajal, S. Davis-Foust, J. Dittel. 2012. Habitat associations of opossums and rodents in a lowland forest in French Guiana. Mammalian Biology, 77: 84-89.

Almeida-Santos, S., M. Antoniazzi, O. Sant'anna, C. Jared. 2000. Predation by the opossum Didelphis marsupialis on the rattlesnake Crotalus durissus. Current Herpetology, 19:1: 1-9.

Alves, R., I. Rosa. 2006. From cnidarians to mammals: The use of animals as remedies in fishing communities in northeast Brazil. Journal of Ethnopharmacology, 107: 259-276.

Alves, R., I. Rosa. 2007. Zootherapeutic practices among fishing communities in north and northeast Brazil. A comparison. Journal of Ethnopharmacology, 111: 82-103.

Austad, S., M. Sunquist. 1987. Sex ratio manipulation in the common opossum. Nature, 324: 58-60.

Brito, D., D. Astuade Moraes, D. Lew, P. Soriano, L. Emmons, A. Cuaron, K. Helgen, R. Reid, E. Vazquez. 2008. "Didelphis marsupialis" (On-line). IUCN Red List of Threatened Species. Accessed May 21, 2013 at .

Cabello, D. 2006. Reproduction of Didelphis marsupialis (Didelphimorphia: Didelphidae) in the Venezuelan Andes. Acta Theriologica, 51:4: 427-433.

Castillo-Flores, A., L. Calvo-Irabien. 2003. Animal dispersal of two secondary-vegetation herbs into the evergreen rainforest of south-eastern Mexico. Journal of Tropical Ecology, 19: 271-278.

Cerqueira, R., C. Tribe. 2008. Genus Didelphis. Pp. 17-27 in A Gardner, ed. Mammals of South America: Marsupials, Xenarthrans, Shrews, and Bats, Vol. 1. Chicago: University of Chicago Press.

Cordero, R., B. Nicolas. 1987. Feeding habits of the opossum (Didelphis marsupialis) in northern Venezuela. Fieldiana: Zoology, 39: 125-131.

Deane, M., H. Lenzi, A. Jansen. 1984. Trypanosoma cruzi: Vertebrate and invertebrate cycles in the same mammal host, the opossum Didelphis marsupialis. Memorias do Instituto Oswaldo Cruz, 79:4: 513-515.

Ehret, G. 1983. Development of hearing and response behavior to sound stimuli: Behavioral studies. Pp. 211-237 in R Romand, ed. Development of Auditory and Vestibular Systems. New York: Academic Press.

Estrada, A., R. Coates-Estrada, D. Merritt Jr. 1994. Non-flying mammals and landscape change in the tropical rainforest region of Los Tuxtlas, Mexico. Ecography, 17:3: 229-241.

Fernandes, F., L. Cruz, E. Martins, S. dos Reis. 2010. Growth and home range size of the gracile mouse opossum Gracilinanus microtarsus (Marsupialia: Didelphidae) in Brazilian cerrado. Journal of Tropical Ecology, 26: 185-192.

Garrett, C., D. Boyer. 1993. Rhinella marina (cane toad) predation. Herpetological Review, 24:4: 148.

Gustavo, A., B. da Fonseca, J. Robinson. 1990. Forest size and structure: Competitive and predatory effects on small mammal communities. Biological Conservation, 53: 265-294.

Jimenez, F., F. Catzeflis, S. Gardner. 2011. Structure of parasite component communities of Didelphis marsupialis: Insights from a comparative study. Journal of Parasitology, 97:5: 779-787.

Julien-Laferriere, D., M. Atramentowicz. 1990. Feeding and reproduction of three didelphid marsupials in two Neotropical forests (French Guiana). Biotropica, 22:4: 404-415.

Junior, P., D. Guimaraes, Y. le Perdu. 2010. Non-legalized commerce in game meat in the Brazilian amazon: A case study. Revista de Biologia Tropical, 58:3: 1079-1088.

Kajin, M., R. Cerqueira, M. Vieira, R. Gentile. 2008. Nine-year demography of the black-eared opossum Didelphis aurita (Didelphimorphia:Didelphidae) using life tables. Brasileira de Zoologia, 25:2: 206-213.

Medellin, R. 1994. Seed dispersal of Cecropia obtusifolia by 2 species of opossums. Biotropica, 26:4: 400-407.

O'Connell, M. 2006. American Opossums. Pp. 808-813 in D MacDonald, S Norris, eds. The Encyclopedia of Mammals, Vol. 1. London: The Brown Reference Group.

Oswaldo-Cruz, E., J. Hokoc, A. Sousa. 1979. A schematic eye for the opossum. Vision Research, 19:3: 263-278.

Pinowski, J. 2005. Roadkills of vertebrates in Venezuela. Revista Brasileira de Zoologica, 22:1: 191-196.

Reid, F. 2009. A field guide to the mammals of Central America and southeast Mexico. Oxford: Oxford University Press.

Reidy, J. 2009. Nest predators of lance-tailed manakins on Isla Boca Brava, Panama. Journal of Field Ornithology, 80:2: 115-118.

Richard-Hansen, C., J. Vie, N. Vidal, J. Keravec. 1999. Body measurements on 40 species of mammals from French Guiana. Journal of Zoology, 247: 419-428.

Rotenberg, J., J. Marlin, L. Pop, W. Garcia. 2012. First record of a harpy eagle (Harpia harpyja) nest in Belize. The Wilson Journal of Ornithology, 124:2: 292-297.

Shripat, V. 2011. "The Online Guide to the Animals of Trinidad and Tobago" (On-line). The University of the West Indies. Accessed May 21, 2013 at .

Sunquist, M., S. Austad, F. Sunquist. 1987. Movement patterns and home range in the common opossum (Didelphis marsupialis). Journal of Mammalogy, 68:1: 173-176.

Tyndale-Biscoe, C. 2005. Life of Marsupials. Collingwood, Australia: Csiro Publishing.

Tyndale-Biscoe, C., R. Mackenzie. 1976. Reproduction in Didelphis marsupialis and D. albiventris in Columbia. Journal of Mammalogy, 57:2: 249-265.

Tyndale-Biscoe, H. 1973. Life of Marsupials. New York: American Elsevier Publishing Company, Inc.

Tyndale-Biscoe, H., M. Renfree. 1987. Reproductive physiology of marsupials. Cambridge: Cambridge University Press.

Vaughan, C., S. Hawkins, L. Foster. 1999. Late dry season habitat use of common opossum Didelphis marsupialis (Marsupialia: Didelphidae) in Neotropical lower montane agricultural areas. Revista de Biologia Tropical, 47: 263-269.

Volchan, E., C. Vargas, J. da Franca, A. Pereira Jr, C. da Rocha-Miranda. 2004. Tooled for the task: Vision in the opossum. Bioscience, 54:3: 189-194.

Sours: https://animaldiversity.org/accounts/Didelphis_marsupialis/

SOUTHERN BLACK-EARED OPOSSUM Didelphis aurita 
Smith P 2009 - FAUNA Paraguay Handbook of the Mammals of Paraguay Number 33 Southern Black-eared Opossum Didelphis aurita
Pdf file 488kb
A large opossum, the Southern Black-eared can be easily distinguished from the more widespread White-eared Opossum by, you guessed the colour of the ears! Of course thats not the only way to tell them apart, they are actually quite different beasts, but they share a similar semi-arboreal lifestyle and omnivorous diet. This species however is far more closely tied to forest environments than its more adaptable relative.
Click on the images to enlarge them.

FIGURE 1 - (FPMAM11PH) Adult, Kuruguaty, Departamento Canindeyú (Philip Myers undated).

FIGURE 1

FIGURE 1

Designed by Paul Smith 2006. This website is copyrighted by law.
Material contained herewith may not be used without the prior written permission of FAUNA Paraguay.
Material on this page was provided by Philip Myers and is used with his permission.

LINKS TO DOWNLOADABLE OPEN ACCESS REFERENCES USED IN THE PREPARATION OF THE FAUNA PARAGUAY HANDBOOK OF THE MAMMALS OF PARAGUAY SPECIES ACCOUNT FOR THIS SPECIES:

Allen JA1902 - A Preliminary Study of the South American Opossums of the Genus Didelphis - Bulletin AMNH 16: p149-188.
Astúa de Morães D, Moura RT, Grelle CEV, Fonseca MT2006 - Influence of Baits, Trap Type and Position for Small Mammal Capture in a Brazilian Lowland Atlantic Forest - Bol. Mus. Biol. Mello. Leitão 19: p19-32.
Brown BE 2004 - Atlas of New World Marsupials - Fieldiana Zoology 102.
Cáceres N2003 - Use of the Space by the Opossum Didelphis aurita Wied-Neuwied (Mammalia Marsupialia) in a Mixed Forest Fragment of Southern Brazil - Revista Brasileira de Zoologia 20: p315-322.
Cáceres NC, Monteiro Filho EL de A 1999 - Tamanho Corporal em Populacões Naturais de Didelphis (Mammalia: Marsupialia) do Sul do Brasil - Revista Brasileira de Biologia 57: p461-469.
Cáceres NC, Monteiro-Filho EL de A2007 - Germination in Seed Species Ingested by Opossums: Implications for Seed Dispersal and Forest Conservation - Brazilian Archives of Biology and Technology 50: p921-928.
Carvalho FMV de, Delciellos AC, Vieira MV2000 - Medidas Externas dos Miembros de Marsupiais Didelfidios: Uma Comparação com Medidas do Esqueleto Pós-Craniano - Boletimdo Museu Nacional, Rio de Janeiro 438.
Carvalho FMV de, Pinheiro PS, Fernández FAS, Nessimian JL1999 - Diet of Small Mammals in Atlantic Forest in Southeastern Brazil - Revista Brasileira de Zoociencias 1: p91-101.
Ceotto P, Finotti F, Santori R, Cerqueira R 2009 - Diet Variation of the Marsupials Didelphis aurita and Philander frenatus (Didelphimorphia: Didelphidae) in a Rural Area of Rio de Janeiro State, Brazil - Mastozoologia Neotropical 16.
Cunha AA, Vieira MV2002 - Support Diameter, Incline and Vertical Movements of Four Didelphid Marsupials in the Atlantic Forest of Brazil - Journal of Zoological Society of London 258: p419-426.
Cunha AA, Vieira MV2005 - Age, Season and Arboreal Movements of the Opossum Didelphis aurita in an Atlantic Rainforest of Brazil - Acta Theriologica 50: p551-560.
Delciellos AC, Vieira MV2006 - Arboreal Walking Performance in Seven Didelphid Marsupials as an Aspect of Their Fundamental Niche - Austral Ecology 31: p449-457.
Delciellos AC, Vieira MV2007 - Stride Lengths and Frequencies of Arboreal Walking in Seven Species of Didelphid Marsupials - Acta Theriologica 52: p101-111.
Delciellos AC, Vieira MV2009 - Allometric, Phylogenetic and Adaptive Components of Climbing Performance in Seven Species of Didelphid Marsupials - Journal of Mammalogy 90: p104-113.
Kajin M, Cerqueira R,Vieira MV, Gentile R 2008 - Nine Year Demography of the Black-eared Opossum Didelphis aurita (Didelphimorphia: Didelphidae) Using Life Tables - Revista Brasileira de Zoologia 25: p206-213.  
Lima SF, Obara AT 2004 - Levantamento de Animais Silvestres Atropelados na BR-277 às Margens do Parque Nacional do Iguaçu - Subsídios ao Programa Multidisciplinar de Proteção à Fauna.
Loretto D, Vieira MV 2005 - The Effects of Reproductive and Climatic Seasons on Movements in the Black-eared Opossum (Didelphis aurita Wied-Neuwied 1826) - Journal of Mammalogy 86: p287-293.
Mendel SM, Vieira MV, Cerqueira R2008 - Precipitation, Litterfall and the Dynamics of Density and Biomass in the Black-eared Opossum Didelphis aurita - Journal of Mammalogy 89: p159-167.
Moura MC, Caparelli AC, Freitas SR, Vieira MV2005 - Scale Dependent Habitat Selection in Three Didelphid Marsupials Using the Spool-and-line Technique in the Atlantic Forest of Brazil - Journal of Tropical Ecology 21: p337-342.
Moura MC, Cerqueira R, Vieira MV2009 - Occasional Intraguild Predation Structuring Small Mammal Assemblages: The Marsupial Didelphis aurita in the Atlantic Forest of Brazil - Austral Ecology IN PRESS
Myers P, Espinosa R, Parr CS, Jones T, Hammond GS, Dewey A 2006 - The Animal Diversity Web (online). Accessed December 2007.
Vieira MV1997 - Body Size and Form in Two Neotropical Marsupials, Didelphis aurita and Philander opossum (Marsupialia: Didelphidae) - Mammalia 61: p245-254.
Vieira MV, Cunha AdeA 2008 - Scaling Body Mass and Use of Space in Three Species of Marsupials in the Atlantic Forest of Brazil - Austral Ecology 33: p872-879.

CLICK THE HANDBOOK LINK ABOVE TO DOWNLOAD OTHER PDFS OF THE SPECIES ACCOUNTS FOR THE FAUNA PARAGUAY HANDBOOK OF PARAGUAYAN MAMMALS VOLUME 1: DIDELPHIMORPHIA.

Sours: http://www.faunaparaguay.com/didelphisaurita.html
  1. Bronx party venues
  2. Tie on stool cushions
  3. 2008 nissan sentra parts diagram

Common opossum

Species of marsupial

For the possum of North America, see Virginia opossum. For all things "possum", see possum (disambiguation).

The common opossum (Didelphis marsupialis), also called the southern or black-eared opossum[2] or gambá, and sometimes called a possum, is a marsupial species living from the northeast of Mexico to Bolivia (reaching the coast of the South Pacific Ocean to the central coast of Peru), including Trinidad and Tobago in the Caribbean,[2] where it is called manicou.[3] It prefers the woods, but can also live in fields and cities.

Habitat and shelter[edit]

This opossum is found in tropical and subtropical forest, both primary and secondary, at altitudes up to 2200 m.[2] They use a wide range of nest sites. Most commonly they will create one in the hollow of a tree; however, they will also dig a burrow or nest in any dark location if nothing else is suitable (which often gets them in trouble with humans). Opossums enjoy denning underground, but do not spend as much time underground when it is dry season. [4] Common predators of the opossum are humans, house pets (ex: dogs and cats), and birds.[5] When they are in danger, they act dead, also called, 'playing opossum.' [6]

Description[edit]

Skeleton, Natural History Museum of Genoa

The common opossum is similar in size to a house cat. The fur of the opossum is actually yellow in the under-fur, but is hidden by the longer black guard-hairs that cover it, while the tail, fingers, and face are lighter "with the tail being without fur, somewhat similar to a giant rat tail".[citation needed] It can measure nearly 20 inches long. It has large ears that are usually black, and its face is usually a pale peach in color, with black whiskers and eyes that reflect reddish in light. With a body length of nearly a foot, and a tail that can reach almost two feet, the common opossum is one of the larger members of its family. An adult can weigh more than three pounds.

Behavior[edit]

Their activity is mainly nocturnal and terrestrial, with some arboreal exploration and nesting. Outside of mating, they are usually solitary. A male opossum's home range (distance traveled at night) can vary in size from wet to dry seasons while a female has a more stationary home range when she is breeding. [7] Males are most active between 11 pm and 3 am at night.[8] They are considered pests due to their somewhat raccoon-like behavior. Raiding trash cans, nesting in locations that are not suitable, and causing mayhem if encountered within a human living space, they are often trapped and killed. D. marsupialis have not been observed to be territorial.[9] The common opossum is a host of the acanthocephalan intestinal parasite Gigantorhynchus lutzi.[10]

Common predators of the opossum are humans, house pets (ex: dogs and cats), and birds.[11] When they are in danger, they act dead, also called, 'playing opossum'.[6]

Diet[edit]

Common opossums have a broad ability to adapt to environmental changes, and their teeth allow them to eat many different types of food, which is obtained mostly on the ground. They can eat small insects, small animals, fruits, vegetables, and also carrion. Their ability to digest almost anything edible gives them a broader range than a human.

Reproduction[edit]

The female will have 5-9 offspring between one and three times per year after maturity. The mother raises the young by herself. The common opossum can mate for the majority of the calendar year. They do not mate for life.[12] Female opossums can give birth to an upmost of 24 infants, however, only a third of them usually survive. Young opossums stay with the mother for the first few months of their lives and reach maturity before they are a year old.

Lifespan[edit]

The common opossum lives for around 2-4years.

Classification[edit]

They are members of the genus Didelphis, which contains the largest American opossums, and the order Didelphimorphia, to which all Western hemisphere opossums belong. The common opossum is currently not an endangered species.[13]

References[edit]

  1. ^Gardner, A.L. (2005). "Order Didelphimorphia". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 5–6. ISBN . OCLC 62265494.
  2. ^ abcdBrito, D.; Astua de Moraes, D.; Lew, D.; Soriano, P.; Emmons, L.; Cuarón, A. D.; Helgen, K.; Reid, R. & Vazquez, E. (2008). "Didelphis marsupialis". IUCN Red List of Threatened Species. 2008. Retrieved 28 December 2008.
  3. ^"Checklist of Mammals of Trinidad and Tobago". Republic of Trinidad and Tobago Biodiversity Clearing House. 2005. Archived from the original on 2010-11-21. Retrieved 2010-10-24.
  4. ^Sunquist, Mel E.; Austad, Steven N.; Sunquist, Fiona (1987). "Movement Patterns and Home Range in the Common Opossum (Didelphis marsupialis)". Journal of Mammalogy. 68 (1): 173–176. doi:10.2307/1381069. ISSN 0022-2372. JSTOR 1381069.
  5. ^"Opossum (Didelphis Virginiana) | Incredible Facts". A-Z Animals.
  6. ^ abMartina, Leila Siciliano. "Didelphis marsupialis (southern opossum)". Animal Diversity Web.
  7. ^Sunquist, Mel E.; Austad, Steven N.; Sunquist, Fiona (1987). "Movement Patterns and Home Range in the Common Opossum (Didelphis marsupialis)". Journal of Mammalogy. 68 (1): 173–176. doi:10.2307/1381069. ISSN 0022-2372. JSTOR 1381069.
  8. ^Vaughan, Christopher S; Foster Hawkins, L (1969-12-31). "Late dry season habitat use of common opossum, Didelphis marsupialis (Marsupialia: Didelphidae) in neotropical lower montane agricultural areas". Revista de Biología Tropical: 263–269. doi:10.15517/rbt.v47i1-2.19075. ISSN 2215-2075.
  9. ^Sunquist, Mel E.; Austad, Steven N.; Sunquist, Fiona (1987). "Movement Patterns and Home Range in the Common Opossum (Didelphis marsupialis)". Journal of Mammalogy. 68 (1): 173–176. doi:10.2307/1381069. ISSN 0022-2372. JSTOR 1381069.
  10. ^Nascimento Gomes, Ana Paula; Cesário, Clarice Silva; Olifiers, Natalie; de Cassia Bianchi, Rita; Maldonado, Arnaldo; Vilela, Roberto do Val (December 2019). "New morphological and genetic data of Gigantorhynchus echinodiscus (Diesing, 1851) (Acanthocephala: Archiacanthocephala) in the giant anteater Myrmecophaga tridactyla Linnaeus, 1758 (Pilosa: Myrmecophagidae)". International Journal for Parasitology: Parasites and Wildlife. 10: 281–288. doi:10.1016/j.ijppaw.2019.09.008. PMC 6906829. PMID 31867208.
  11. ^"Opossum (Didelphis Virginiana) | Incredible Facts". A-Z Animals.
  12. ^Medellín, Rodrigo A. "Didelphimorphia (New World Opossums)." Grzimek's Animal Life Encyclopedia, edited by Michael Hutchins, et al., 2nd ed., vol. 12: Mammals I, Gale, 2004, pp. 249-265. Gale eBooks, https://link.gale.com/apps/doc/CX3406700770/GVRL?u=ucberkeley&sid=GVRL&xid=34d8ffc5.
  13. ^"Funk, Isaac Kaufman, (10 Sept. 1839–4 April 1912), author; President Funk & Wagnalls Company; Editor-in-chief of the various periodicals of Funk & Wagnalls Company; Editor-in-chief of the Funk & Wagnalls Standard Dictionary, new edition revised 1903; Chairman of Editorial Board that produced Jewish Encyclopædia", Who Was Who, Oxford University Press, 2007-12-01, doi:10.1093/ww/9780199540884.013.u186193, retrieved 2020-11-17
Sours: https://en.wikipedia.org/wiki/Common_opossum
GIANT OPOSSUM! Possible World Record

Geographic Range

Big-eared opossums (Didelphis aurita) are Neotropical marsupials found along the Atlantic coast of Brazil to northeastern Argentina and southeastern Paraguay. ("InfoNatura: Birds, mammals and amphibians of Latin America", 2003; Emmons, 1997)

Habitat

Big-eared opossums live in Atlantic rainforests, secondary Atlantic forests, and Araucaria highlands. They are also found in forests fragmented by urban development and deforestation. Their habitat has are two discrete seasons, a warm rainy season, which lasts from September to March and a cool dry season, which lasts from April to August. The mean annual temperature in their habitat is between 17 and 24°C, with a mean annual rainfall of 1,350 to 2,000 mm. (Caceres and Monteiro-Filho, 2001; Caceres, 2003; Cerqueira and Lemos, 2000; Emmons, 1997; Grelle, 2003; Leite, et al., 1996)

Physical Description

Big-eared opossums closely resemble another Neotropical marsupial, common opossums (Didelphis marsupialis). In fact, this species was once considered a subspecies of D. marsupialis. Big-eared opossums have prominent facial markings and a conspicuous black line down the center of their forehead. Their ears are naked and black. Their fur is dirty yellow, with black or gray tips. Big-eared opossums have long, prehensile tails that are furred at the base. The fur at the base of their tail is about as long as their hind legs and is at least half black and half white; the black portion is sometimes longer. In contrast, common opossums (Didelphis marsupialis) do not have as much fur on the base of their tail and they usually have a shorter black portion. Aside from geographic location, this is one characteristic that can be used to distinguish the species. (Caceres, 2003; Emmons, 1997; Hume, 1999)

Male big-eared opossums tend to be larger than females. Adult males range from 1,500 to 1,880 grams during the reproductive season. Females can weigh anywhere from 1,000 to 1,300 grams in the reproductive season. (Caceres, 2003)

Reproduction

Big-eared opossums are considered promiscuous. The home ranges of non-territorial males overlap with the home ranges of several territorial females and other non-territorial males. Therefore, females defend areas with sufficient resources and males seeking mates roam to find them. Licking and scratching of the cervical scent gland and vocalization helps males find females. (Caceres, 2003; Nogueira and Castro, 2003)

In the case of big-eared opossums, the breeding season coincides with the wet season, when fruit is most abundant. Like other marsupials, big-eared opossums undergo a brief gestation period and give birth to tiny young that crawl into the mother’s pouch where they attach to a nipple and feed for about 100 days. Weaning generally occurs at the end of the rainy season, while food is still available for the young. Females may synchronize their reproduction by photoperiod. Individuals born at the end of the current breeding season are able to reproduce at the start of the next breeding season. Using information from other South American Didelphids like common opossums, females can have 2 to 3 litters per breeding season, with an average of 7.3 young per litter. (Eisenberg and Redford, 1999; Gentile, et al., 2000; Gentile, et al., 1995)

Female big-eared opossums carry young in their pouches until weaning, which could be up to 100 days from birth. This provides protection and nutrition for the under-developed young. (Gentile, et al., 1995)

  • pre-weaning/fledging
    • provisioning
    • protecting

Lifespan/Longevity

Little information is available on the lifespan of big-eared opossums, but their close relative common opossums have an average lifespan of 2 years in the wild. (Hagmann, 2003)

Behavior

Big-eared opossums are scansorial, nocturnal and solitary. They are mainly terrestrial, but their relatively long forelimbs and claws allow them to easily climb trees. It has been argued that big-eared opossums are exclusively terrestrial and only go into trees to escape flooding, but other studies have shown that using proper techniques, big-eared opossums can be trapped or tracked in trees as frequently as on the ground. This scansorial behavior may allow for some resource partitioning and alleviate some competition between big-eared opossums and other opossums in the area, like the terrestrial brown four-eyed opossums and the arboreal bare-tailed woolly opossums. (Caceres, 2003; Cerqueira and Lemos, 2000; Cuhna and Vieira, 2002; Leite, et al., 1996)

Home Range

The average home range size for female big-eared opossums is 0.6 to 1.7 hectares in the non-reproductive season and 0.6 to 1.3 hectares in the reproductive season, when resources are more abundant. Females may also have a hierarchy, determining which female get the best territory. Males have a much larger home range of 2.3 to 2.7 hectares. (Caceres, 2003)

Communication and Perception

Big-eared opossums have a cervical scent gland. A scent-marking behavior can release the secretions of this sebaceous gland into the environment, where it is used for social communication. (Nogueira and Castro, 2003)

Food Habits

Big-eared opossums are opportunistic omnivores that mostly feed on arthropods and fruit; but also consume other invertebrates and small vertebrates. Scat sampling has identified several dietary items including rubbish consumed by animals living in urban areas. These animals are known to consume the following invertebrates: millipedes, harvestmen, beetles, grasshoppers and crickets, gastropods, butterfly larvae, ants, isopods and crabs. Big-eared opossums are also known to eat fruit from 13 different families including 22 identified species. Most fruit is consumed during the wet season when it is most abundant. Ingested vertebrates include rufous-bellied thrushes, the snake Liotyphlops beui, southeastern four-eyed opossums, fish and other small mammals. (Caceres and Monteiro-Filho, 2001; Caceres, 2003; Cuhna and Vieira, 2002; Hume, 1999; Leite, et al., 1996)

  • birds
  • mammals
  • reptiles
  • fish
  • insects
  • terrestrial worms
  • aquatic crustaceans

Predation

Information on predators specific to this species is not available, but some of the larger carnivores in their region include ocelots, pumas and jaguarundis. Jararacas are another likely predator. Jararacas are nocturnal venomous pitvipers in a group commonly known as lanceheads. Their close relative Bothrops asper is also known to feed on common opossums in Mexico and Guatemala. (Emmons, 1997; Greene, 1997; Mattison, 1999)

In response to a predator, big-eared opossums may act like their relative Virginia opossums and "play possum", or feign death to fool a predator. Additionally, common opossums are surprisingly resistant to the venomous bite of Bothrops asper. Big-eared opossums may have similar resistance to the venom of jararacas (Bothrops jararaca). (Greene, 1997; Hagmann, 2003)

Ecosystem Roles

Big-eared opossums and other South American marsupials are the preferred host of the tick species Ixodes loricatus. Big-eared opossums prey upon many different kinds of insects and fruits. The latter may help seed dispersal. (Barros-Battesti, et al., 2000)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Possible economic benefits may include ecotourism because of their abundance in tropical rainforests.

Economic Importance for Humans: Negative

Ixodes loricatus is a tick that prefers marsupial hosts and is involved in the transmission of Lyme disease. As much as 26% of big-eared opossums may be infested with this tick. (Barros-Battesti, et al., 2000)

  • injures humans

Conservation Status

Big-eared opossums are one of the most common marsupials in their home range. They were trapped with the highest frequency in most studies conducted in coastal Brazil involving small mammals. However, deforestation rates in that area are high and only 5% of the original rainforest remains. This may pose a threat to big-eared opossums and other rainforest species in the future. (Cuhna and Vieira, 2002; Gentile, et al., 2000; Grelle, 2003; Leite, et al., 1996; Pires, et al., 2002)

Contributors

Leila Siciliano Martina (editor), Animal Diversity Web Staff.

Matthew Wund (editor), The College of New Jersey.

Patrick Cusick (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), University of Michigan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

2003. "InfoNatura: Birds, mammals and amphibians of Latin America" (On-line). Accessed February 11, 2004 at .

Barros-Battesti, D., N. Yoshinari, V. Bonoldi, A. Gomes. 2000. Parasitism by Ixodes loricatus and I. loricatus (Acari: Ixodidae) on small wild mammals from an Atlantic forest in the state of Sao Paulo, Brazil. Journal of Medical Entomology, 37(6): 820-827.

Caceres, N. 2003. Use of the space by the opossum Didelphis aurita Wied-Newied (Mammalia, Marsupialia) in a mixed forest fragment of southern Brazil. Revista Brasileira de Zoologia, 20 (2): 315-322.

Caceres, N., E. Monteiro-Filho. 2001. Food habits, home range and activity of Didelphis aurita (Mammalia, Marsupialia) in a forest fragment of southern Brazil. Studies on Neotropical Fauna and Environment, 36(2): 85-92.

Cerqueira, R., B. Lemos. 2000. Morphometric differentiation between Neotropical black-eared opossums, Didelphis marsupialis and D. aurita (Didelphimorphia, Didelphidae). Mammalia, 64(3): 319-327.

Cuhna, A., M. Vieira. 2002. Support diameter, incline, and vertical movements of four didelphidmarsupials in the Atlantic forest of Brazil. Journal of Zoology, 258: 419-426.

Eisenberg, J., K. Redford. 1999. Mammals of the Neotropics: The Central Neotropics, Vol. 3. Chicago: University of Chicago Press.

Emmons, L. 1997. Neotropical Rainforest Mammals: A Field Guide 2nd ed.. Chicago: University of Chicago Press.

Gentile, R., P. D'Andrea, R. Cerqueira. 1995. Age structure of two marsupial species in a Brazilian restinga. Journal of Tropical Ecology, 11: 679-682.

Gentile, R., P. D'Andrea, R. Cerqueira, L. Maroja. 2000. Population dynamics and reproduction of marsupials and rodents in a Brazilian rural area: a five year study. Studies on Neotropical Fauna and Environment, 35: 1-9.

Greene, H. 1997. Snakes: The evolution of mystery in nature. Berkeley and Los Angeles, CA: University of California Press.

Grelle, C. 2003. Forest structure and vertical stratification of small mammals in a secondary Atlantic forest, southeastern Brazil. Studies on Neotropical Fauna and Environment, Vol. 38 (2): 81-85.

Hagmann, K. 2003. "Didelphis marsupialis" (On-line). Animal Diversity Web. Accessed February 11, 2004 at .

Hume, I. 1999. Marsupial Nutrition. Cambridge, UK: Cambridge University Press.

Leite, Y., L. Costa, J. Stallings. 1996. Diet and vertical space use of three sympatric opossums in a Brazilian Atlantic forest reserve. Journal of Tropical Ecology, 12: 435-440.

Mattison, C. 1999. Snake. London: DK publishing, Inc..

Nogueira, J., A. Castro. 2003. Male genital system of South American didelphids. Pp. 201 in M Jones, C Dickman, M Archer, eds. Predators With Pouches: The Biology of Carnivorous Marsupials. Collingwood, VIC: CSIRO.

Pires, A., P. Lira, F. Fernandez, G. Schittini, L. Oliveira. 2002. Frequency of movements of small mammals among Atlantic coastal forest fragments in Brazil. Biological Conservation, 108: 229-237.

Sours: https://animaldiversity.org/accounts/Didelphis_aurita/

Eared opossum black

Precipitation, Litterfall, and the Dynamics of Density and Biomass in the Black-Eared Opossum, Didelphis aurita

Abstract

Density and biomass may reveal different aspects of the dynamics of populations, but most studies have focused on density or relative abundance. Density and biomass also may behave differently in parts of the population composed of males and females because of differences in vagility and parental care between sexes. Herein, we explore seasonal and multiannual variation in density and biomass in a population of black-eared opossums (Didelphis aurita). Females and males were analyzed separately for associations with precipitation and litterfall, indicators of resource availability. Litterfall, density, and biomass were estimated from 1997 to 2003 on three 0.64-ha trapping grids in an area of Atlantic Forest in Rio de Janeiro, Brazil. Density of females exhibited a significant increase during the study. Density and biomass of males were more variable, without any significant positive trend or correlation with precipitation or litterfall. Seasonal and biannual patterns of precipitation were detected, followed by the density and biomass of females with time lags varying from 0 to 1, and from 9 to 12 months. The relative stability of biomass of females, and its association with precipitation and litterfall, suggests that resource availability combined with density-dependent responses regulated the local population of females. The local population of males may be more influenced by the stochasticity resulting from the higher vagility of males.

Resumo

Densidade e biomassa podem revelar aspectos diferentes da dinâmica das populações, mas a maioria dos estudos tern enfocado densidade ou abundãncia relativa. Densidade e biomassa podem também se comportar de forma diferente se comparadas entre machos e fêmeas devido a diferenças de vagilidade e cuidado parental entre os sexos. Neste trabalho exploramos a variação sazonal e multianual de densidade e biomassa em uma população de gambás de orelha preta, Didelphis aurita. Fêmeas e machos foram analisados separadamente para associações com precipitação e queda de folhas, indicadores de disponibilidade de recursos. A queda de folhas, densidade e biomassa foram estimadas de 1997 a 2003 em 3 grades de armadilha de 0,64 ha, em uma área de Floresta Atlântica do Rio de Janeiro, Brazil. A densidade de fêmeas aumentou significativamente durante o estudo. Densidade e biomassa de machos foram mais variáveis, sem nenhuma tendência significativa de aumento ou correlação com precipitação ou queda de folhas. Padrões sazonais e bianuais de precipitação foram detectados, seguidos pela densidade e biomassa de fêmeas com defasagens variando de 0 a 1, e de 9 a 12 meses. Densidade e biomassa de fêmeas também seguiu a sazonalidade da queda de folhas, mas com uma defasagem de 1 ou 2 meses. A relativa estabilidade da biomassa das fêmeas, e sua associação com precipitação e queda de folhas, sugerem que a disponibilidade de recursos combinada com respostas dependentes da densidade regularam a população local de fêmeas. A população local de machos podem ser mais influenciada pela estocasticidade relacionada à maior vagilidade dos machos.

biomass, Brazil, density, Didelphis aurita, resource availability, time-series analyses

Patterns in the dynamics of animal populations have long been of interest to ecologists (Kendall et al. 1999; Murdoch 1994), and understanding the nature of this variability is one of the primary objectives of population biology (Erb et al. 2001). One approach to this objective is to determine the mechanisms that regulate population density over time, that is, mechanisms that keep their abundance within a range narrower than would be expected by density-independent factors alone (Berryman et al. 2002).

Temporal variation in a population can be described by 2 parameters, density and biomass, but density may be more affected by environmental stochasticity than is biomass. Density may be more directly influenced by individual behavior, particularly the movement of individuals, which is more likely to track and respond to the environmental stochasticity than is biomass. Environmental stochasticity includes the daily variation in resource acquisition by individuals, risk of predation, and disease, which could result in short-term changes in their movements (e.g., Russell et al. 2003). Biomass, expressed as mass per area, reflects the quantity of resources incorporated by the population, representing its role in the ecosystem in terms of energy (Odum 1985). The incorporation of resources into biomass takes some time to occur, reflecting resources available over a time period longer than the daily variation in resource acquisition by individuals. Thus, we expect that biomass would follow a more seasonal and stable pattern compared to density. Comparison of the dynamics of density and biomass could be important to understanding the dynamics of populations, but most theoretical and empirical studies of vertebrates have focused only on the temporal variation of density or relative abundance (e.g., Brady and Slade 2004).

In mammals with a promiscuous or polygynous mating system, density and biomass of males and females may respond differently (Greenwood 1980; Waser 1985). This is the case for didelphid marsupials, whose males move more than females to attain the largest number of mates (Davis 1947; Loretto and Vieira 2005; Sandell et al. 1990). Females tend to use a smaller area during pregnancy and lactation, because of the extra mass or care that the offspring demand (Gentile and Cerqueira 1995; Hossler et al. 1994; Loretto and Vieira 2005), and reside in an area longer than males (Bergallo 1994; Rademaker 2001). In the black-eared opossum (Didelphis aurita Wied-Newied, 1826) movement of males is mainly related to the reproductive season, whereas movement of females is more affected by climatic seasons (Loretto and Vieira 2005). The larger movements of male D. aurita may result in more frequent oscillations of their density compared to females.

To understand how environmental factors affect density and biomass requires study in at least 2 temporal scales, seasonal and multiannual (Crespin et al. 2002; Lima et al. 2001). Time-series analysis is the appropriate tool for exploration of temporal variation in these parameters (Kesner and Linzey 1997). Regarding small mammals of the tropics, long-term studies of population dynamics are rare, except for the studies carried out in Chile (Lima et al. 2001) and Brazil (Cerqueira et al. 1993; Gentile et al. 2000, 2004). A long-term capture–recapture study of a population of D. aurita has been conducted in the Atlantic Forest of Brazil since 1997. This is 1 of the longest time series available for a small mammal in the Atlantic Forest, and provides an opportunity to compare the temporal variation of density and biomass considering seasonal and multiannual factors.

In this study, we compare the seasonal and multiannual variation of density and biomass of D. aurita considering the entire population, and males and females separately. Possible associations between the dynamics of density and biomass, and the dynamics of age structure and resource availability also are explored. Our hypotheses are that density of D. aurita is more affected by environmental stochasticity than is biomass, and that the dynamics of density and biomass differ between male and female D. aurita.

Materials and Methods

Study area.—Our study was conducted in the Coastal Forest of the Serra do Mar, a subdivision of the Atlantic Forest biome (Dinerstein et al. 1995), located in Garrafão, in Parque Nacional da Serra dos Órgãos, municipality of Guapimirim, state of Rio de Janeiro, Brazil (22°28′28″S, 42°59′86″W). The forest of the region is part of 1 of the largest continuous expanses of Atlantic Forest remaining (SOS Mata Atlântica/INPE/ISA 1998). The area is surrounded by holiday houses that could influence the structure and composition of the forest (Freitas 1998). Mendel and Vieira (2003) provide a more detailed description of the area.

Mean monthly temperature varied between 15.5°C and 24.9°C, and total monthly rainfall varied from 0 to 508 mm (Fig. 1a; data from Instituto Nacional de Meteorologia–INMET, Rio de Janeiro, meteorological station at Nova Friburgo, Rio de Janeiro, Brazil). Monthly mean precipitation was used to divide the period of study into dry and wet seasons of equal duration. The 6 consecutive months of low mean precipitation occurred from April to September, defined as the dry season, and months with high precipitation occurred from October to March, defined as the wet season. However, periods of real hydric deficit are unlikely in the region.

Fig. 1

Precipitation, a) temperature, b) autocorrelogram of precipitation, c) litterfall, and d) autocorrelogram of litterfall in Garrafão during the study period.

Fig. 1

Precipitation, a) temperature, b) autocorrelogram of precipitation, c) litterfall, and d) autocorrelogram of litterfall in Garrafão during the study period.

Trapping and handling.—Animals were captured–marked–recaptured from April 1997 to February 2003, as part of a study on the population dynamics of small mammals. Spool-and-line devices were used only after February 1998. Trapping sessions were conducted bimonthly, with each session comprising 5 nights, on three 0.64-ha grids (80 × 80 m2), named A, B, and C, established at 3 elevations (A = 748 m, B = 652 m, and C = 522 m above sea level). Distance between grids A and B was 853 m, and distance between grids B and C was 573 m. During the period of study only 1 individual marked on 1 grid was recaptured on another grid. Each grid had a total of 25 trap stations, 20 m apart, distributed in 5 parallel lines. Two live traps were placed at each station, both on the ground: 1 Tomahawk trap (40.6 × 12.7 × 12.7 cm; Tomahawk Live Trap Co., Tomahawk, Wisconsin) baited with a piece of bacon and meat; and 1 Sherman trap (7.6 × 9.5 × 30.5 cm; H. B. Sherman Traps, Inc., Tallahassee, Florida), baited with peanut butter mixed with banana, bacon lard, and oats. Five large Tomahawk traps (50.8 × 17.8 × 17.8 cm) were distributed along the midlines of the grid, alternating trap stations in north–south and west–east directions.

Traps were checked at sunrise and rebaited if necessary. Individuals were marked with numbered ear tags (National Band and Tag Co., Newport, Kentucky) on both ears to minimize loss of marks, or by tail tattooing. All animals were weighed and measured (length of head and body, and length of tail), sex was determined, and their dental development was recorded.

After identification and measurement, animals were equipped with a spool-and-line device based on that of Boonstra and Craine (1986) and released at the same trap station. For details on the spool-and-line technique, see Mendel and Vieira (2003) and Loretto and Vieira (2005). Trapping and handling conformed to guidelines sanctioned by the American Society of Mammalogists (Gannon et al. 2007).

Litterfall.—Litter arthropods are an important food item for D. aurita (Freitas et al. 1997; Santori et al. 1995) even though other food items are consumed (Astúa de Moraes et al. 2003; Cáceres and Monteiro-Filho 2001). Thus, litterfall biomass was used as a proxy for food availability. Also, in many neotropical forests litterfall follows the precipitation regime (Charles-Dominique et al. 1981; Morellato et al. 2000). From April 1997 until February 2003, litter was collected monthly in 5 litter traps (0.5 × 0.5 m) on each trapping grid, aligned along a diagonal crossing the grid. Five litter traps are sufficient to detect litterfall production and variation in this study area (Finotti et al. 2003). Litter was oven-dried at 80°C for 24 h and weighted to the nearest 0.01 g. Production was expressed as the mean production per trapping grid in tons per hectare.

Density and biomass estimates.—Density and biomass were estimated as the ratio between the minimum number of individuals known alive in a trapping session (Krebs 1966) or their total mass, and the estimated effective area of the trapping grids, A(W). Pouch young were not included in estimates of density and biomass. Density and biomass may vary regardless of changes in the number of individuals simply because the movement areas of individuals vary (Gurnell and Gipps 1989; Johnson et al. 1987). This problem is related to the concept of edge effect on trapping grids (Stickel 1954; Tanaka 1980), which is particularly important for the distances that opossums are likely to move (e.g., Stout and Sonenshine 1974). For opossums, a trapping grid would have to be at least 10 ha or more to make edge effects negligible. Such sizes of trapping grids are impossible to implement and manage on the steep and rough terrain of the Coastal Atlantic Forest of Brazil. Replicates would be even more difficult for such large grids. The 0.64-ha grids used in this study, and the estimate of their effective area for each season and sex, are a feasible design that minimizes the problem of edge effects.

One way to deal with edge effects is to estimate the effective sampling area of the trapping grid, A(W), which is the grid area plus the area of a boundary strip of width W. We estimated W as one-half the mean maximum distance moved (MaxDspool in Mendel and Vieira [2003]), estimated with the spool-and-line technique. Male and female D. aurita respond differently to reproductive and climatic seasons (Loretto and Vieira 2005). Thus, A(W) for males and females was calculated differently, with data for males and females divided by reproductive and climatic seasons, respectively. To illustrate the effect of disregarding differences between sexes, A(W) also was calculated for the entire population, and compared between wet and dry seasons.

Individuals of D. aurita captured on the 3 grids were considered part of a single population because population parameters were very similar and synchronized (Gentile et al. 2004); hence, minimum numbers of individuals known alive of the 3 grids were pooled. In June 1997, when no individuals of D. aurita were captured or were present in the study area, we assumed a minimum value of 0.1 individual/ha for density and a value of 100 g/ha for biomass to make possible the transformation of these variables.

In months when an individual was not captured but was known alive, its mass was determined in 2 manners. For individuals captured as young at the 1st capture and as adults at the last capture, the following potential equation was adjusted
formula
where Mfis the final mass, the mass of the individual at its last capture; Miis the initial mass, the mass of the individual at its 1st capture; tfis the number of months between the 1st and the last capture; and b, the coefficient of the equation, is the growth rate (D'Andrea et al. 1994). With an estimate of b,body mass was estimated for an intermediate month (=tf). For individuals captured as adults at the 1st capture, the harmonic mean (Sokal and Rohlf 1995) between the 1st and the last measures of mass was used, assuming that after reaching the adult class their masses did not vary greatly. For each year, mean individual mass was calculated based on the ratio between the total annual mass and the number of individuals captured in the year, regardless of age and sex.

Age structure.—Age structure of the population was analyzed by classifying individuals in 4 classes according to the pattern of dental eruption (Gentile et al. 1995; Macedo et al. 2006). The 1st class comprised pouch young, the 2nd comprised sexually immature young, the 3rd comprised subadults or sexually active young, and the 4th comprised adults. The proportion of the population comprised of each age class was examined separately for each trap session. In June 1997, when no individuals of D. aurita were captured, the geometric mean between age class proportions of the previous and the following trap session was used.

Time-series analyses.—Seasonal and multiannual variations of density and biomass of male and female D. aurita, as well as the effect of resource availability on these population parameters, were determined with time-series analyses. These techniques have been applied to data from natural populations of small mammals (e.g., Brown and Heske 1990; Garsd and Howard 1981, 1982; Hornfeldt 1994), but require data sets that are both long (a minimum of 50 sample points recommended) and continuous (Legendre and Legendre 1998). Although the estimates of density and biomass of D. aurita presented here do not reach the suggested minimum number of 50 sample points, we considered the 6 years of the study (corresponding to 36 sample points) of sufficient duration and quality to initiate exploratory analysis of population variation using time-series analyses.

Times-series analyses require series to be normal and stationary, which means constant mean and variance through the series, without a seasonal trend (Hipel and McLeod 1994). The presence of a statistically significant trend was examined with Kendall's rank correlation (τ) between the rank-ordered series and the original series (Legendre and Legendre 1998). This test was applied to data for males and females separately, and to the entire population. Additionally, sample autocorrelograms with lags ranging from 1 to 12 were estimated from all the series. The autocorrelation for nonstationary series declines very slowly to zero (Rasmussen et al. 1993). When a seasonal trend was detected, seasonal differentiation was applied (e.g., subtraction of precipitation at time t – 12 from precipitation at time t). Time-series analyses were done in Statistica 5.0 (StatSoft, Inc. 1996).

Cross-correlation analyses were used to evaluate the effects of precipitation on litterfall, and on density and biomass of male and female D. aurita. The effects of litterfall on density and biomass of males and females also were evaluated. This analysis requires that observations in the series be equally spaced and have the same length. If they are not, missing data may be calculated by interpolation (Hipel and McLeod 1994; Legendre and Legendre 1998). Thus, because trap sessions were bimonthly, the values of months without trap sessions were interpolated by the mean between adjacent months (Stat-Soft, Inc. 1996). Precipitation and litterfall were always lagged relative to density or biomass, which were fixed. Assuming that density and biomass respond to precipitation and litterfall (not vice versa), positive lags indicate the extension of the lag in the response of density or biomass to precipitation or litterfall. Negative lags represent simply the extent that density or biomass from the previous year precede the precipitation of the current year, but do not represent a cause-and-effect relationship.

The square-root transformation was the best transformation to achieve normality in time series of precipitation, density, and biomass of D. aurita. For litterfall, however, the log-transformed data was used to better approximate normality.

Results

Time series of precipitation and litterfall.—The time series of precipitation revealed a linear decrease in the coefficients of autocorrelation (lag 1: r = 0.668, SE = 0.108; lag 2: r = 0.356, SE = 0.108; lag 3: r = 0.023, SE = 0.107). This indicates that the series followed seasonal recurrent cycles, supporting the need for seasonal differencing to achieve stationarity. The seasonality in precipitation is to be expected and it was evident by visual inspection of the time series (Fig. 1a). After differencing, precipitation followed a biannual cycle in the period of the study, as demonstrated by the significant negative coefficient at lags 11 (r = −0.25, SE = 0.12) and 12 (r = −0.41, SE = 0.11; Fig. 1b). Precipitation alternated between low and high values between the years of study.

Litterfall increased from the end of the dry season until the 2nd half of the wet season, with 2 peaks each year, normally in September and in January–February (Fig. 1c). Litterfall exhibited significant positive autocorrelation only with lag 1, without any evidence of seasonal or multiannual pattern (r = 0.272, SE = 0.116; Fig. 1d).

Time series of density and biomass.—A total of 207 individuals of D. aurita (114 males and 93 females) were captured 423 times from April 1997 until February 2003, with a trapping effort of 29,700 trap-nights. Of these, 32 males and 37 females were tracked with the spool-and-line device. Effective areas of trapping grids were 2.68 and 2.25 ha for the dry and wet season, respectively. For males, effective areas were 2.12 and 2.85 ha in the nonreproductive and reproductive seasons, respectively, and for females 2.69 and 2.11 ha in dry and wet seasons, respectively.

Density of the entire population (d) exhibited a significant trend of increase during the first 3 years of the study (τd = 0.353, P = 0.002), whereas biomass (b) did not present any trend (τb = 0.041, P = 0.723; Fig. 2a). Mean individual mass varied from 819.95 g in 2001 to 1,416.48 g in 1998. The period between 1997 and 1999 had the highest mean individual masses, compared to 2000 and 2001. In 2002, mean individual mass increased again.

Fig. 2

Density and biomass of Didelphis aurita in Garrafão during the study period. a) Entire population. b) Males. c) Females.

Fig. 2

Density and biomass of Didelphis aurita in Garrafão during the study period. a) Entire population. b) Males. c) Females.

When density and biomass were analyzed separately for each sex, density and biomass were more variable for males than for females (Figs. 2b and 2c). For males, there was no significant trend in the time series of density (dm) or biomass (bm; τdm = 0.117, P = 0.314; τbm = 0.041, P = 0.723; Fig. 2b). Indeed, autocorrelations did not suggest seasonal or multiannual patterns in density or biomass of males (Figs. 3a and 3b).

Fig. 3

Autocorrelograms of density and biomass of Didelphis aurita in Garrafão. Dotted lines are the limits of the 95% confidence interval (r = Pearson correlation; SE = standard error).

Fig. 3

Autocorrelograms of density and biomass of Didelphis aurita in Garrafão. Dotted lines are the limits of the 95% confidence interval (r = Pearson correlation; SE = standard error).

For females, density (df) presented a significant trend of increase (τdf = 0.317, P = 0.007; Fig. 3c). No significant seasonal trend was detected in the biomass (bf; τbf = 0.010, P = 0.935; Fig. 3d), but biomass exhibited a biannual cycle, as indicated by the significant autocorrelations at lags 1 and 12 (lag 1: r = 0.346, SE = 0.160; lag 12: r = 0.345, SE = 0.132; Fig. 3d). Each lag corresponds to a 2-month interval in density and biomass autocorrelations.

Density, biomass, and effect of age structure.—Young and subadults were present from February to June, with a greater proportion of young in February and in April, and of subadults in June (Fig. 4). Adults were present in most months, reaching peaks in October (Fig. 4). They were less frequent in the dry season, mainly in April and in August (Fig. 4).

For males, density was not correlated with any age class (young: r = −0.072, P = 0.675; subadults: r = −0.038, P = 0.826; adults: r = 0.237, P = 0.165), but biomass was was negatively related to the number of young, and positively to the number of adults (young: r = −0.389, P = 0.019; subadults: r = 0.023, P = 0.895; adults: r = 0.482, P = 0.003).

For females, density was positively correlated with the number of young, and negatively with the number of subadults (young: r = 0.434, P = 0.008; subadults: r = −0.558, P = 0.000; adults: r = 0.142, P = 0.408). Biomass of females also was negatively correlated with the number of subadults, but positively with the number of adults (young: r = −0.086, P = 0.618; subadults: r = −0.598, P = 0.000; adults: r = 0.567, P = 0.000).

Cross-correlations.—Litterfall tended to precede precipitation by 1 month, as suggested by the significant positive correlation with lag 11 (Fig. 5). Litterfall also correlated negatively with precipitation, at intermediate lags (Fig. 5), a result of the seasonality in precipitation.

Fig. 5

Cross-correlation between precipitation and litterfall in Garrafão from April 1997 to February 2003. Dotted lines are the limits of the 95% confidence interval (r = Pearson correlation; SE = standard error).

Fig. 5

Cross-correlation between precipitation and litterfall in Garrafão from April 1997 to February 2003. Dotted lines are the limits of the 95% confidence interval (r = Pearson correlation; SE = standard error).

For males, density and precipitation were not correlated, and biomass was weakly and negatively correlated with precipitation at lags 1 and 12 (Figs. 6a and 6b). Density and biomass of males were not correlated with litterfall at any lag. For females, however, density and biomass followed the seasonal pattern of precipitation. Density of females responded immediately to precipitation, with highest correlations at lags 0 and around 12 (Fig. 6c). Biomass of females also responded to precipitation, but with approximately a 10-month lag (Fig. 6d). Significant negative correlations also were observed at lags intermediate between 0 and 10, for density and biomass of females (Figs. 6c and 6d), more evidence of seasonality. Density and biomass of females also were positively correlated with litterfall at lags 0, 1, and 2 (Figs. 7a and 7b), but the correlation was weaker than the correlation with precipitation.

Fig. 6

Cross-correlations between precipitation and density and biomass of males and females. The values of months without trap sessions were interpolated by the mean between adjacent months. Dotted lines are the limits of the 95% confidence interval (r = Pearson correlation; SE = standard error).

Fig. 6

Cross-correlations between precipitation and density and biomass of males and females. The values of months without trap sessions were interpolated by the mean between adjacent months. Dotted lines are the limits of the 95% confidence interval (r = Pearson correlation; SE = standard error).

Fig. 7

Cross-correlations between litterfall and density and biomass of females. The values of months without trap sessions were interpolated by the mean between adjacent months. Dotted lines are the limits of the 95% confidence interval (r = Pearson correlation; SE = standard error).

Fig. 7

Cross-correlations between litterfall and density and biomass of females. The values of months without trap sessions were interpolated by the mean between adjacent months. Dotted lines are the limits of the 95% confidence interval (r = Pearson correlation; SE = standard error).

Discussion

When the entire population of D. aurita was analyzed without considering sex differences, temporal variation in density and biomass behaved differently in response to the same environmental conditions. Only when the data were analyzed separately for females and males did it become clear that the significant trend in density for the entire population reflected the density of females. The crash in the density and biomass of males in 1999 prevented detection of a significant trend for males. The significant trend in the density of females without a corresponding trend in their biomass confirms the hypothesis that biomass is more stable than density, but only for females.

The increasing density of females without an associated increase in biomass suggests that many individuals had progressively reduced access to resources. Accordingly, there was a decrease in the mass of individuals from 1998 until 2001 (S. M. Mendel, in litt.), which was compensated by the increasing number of females. Such compensation suggests regulation by resource availability combined with a density-dependent process. Availability of food resources, inferred by precipitation and litterfall, usually triggers density-dependent responses (reviewed in Hixon et al. 2002), creating a negative feedback structure that results in population regulation (Berryman et al. 2002). If food availability had a purely density-independent effect on females, biomass and density would have similar dynamics, both tracking food availability.

The detection of a biannual trend for females but not for males may result from the lower vagility of individual females, and consequently reduced stochasticity in the number of individuals moving in and out of the local population. Females reside longer in the area than males (Rademaker 2001), which seems to be the general pattern for species of Didelphis (Cáceres 2000; Stout and Sonenshine 1974; Talamoni and Dias 1999). Females also move significantly less than males during most of the year, and particularly in the reproductive season (Loretto and Vieira 2005). In the polygynous mating system of Didelphis, males attempt to mate with the greatest possible number of females, and frequently disperse in response to agonistic encounters with other males (Ryser 1992). In our study, there was a higher frequency of wounds on males during periods of high density (S. M. Mendel, in litt.), supporting this hypothesis for D. aurita.

Density and biomass of females seem to be affected by both precipitation and litterfall. The alternation of years of high and low levels of precipitation may be temporary, rather than a lasting biannual cycle. Such a biannual precipitation cycle does not occur in the climatological normals of temperature and precipitation for the region of Teresópolis (INMET 1979). Even if restricted to the period of study, such a biannual cycle could produce a similar pattern in litterfall and density and biomass of D. aurita. Indeed, the biannual cycle was detected for the biomass of females, but biomass of females tracked the precipitation biannual cycle with an approximately 10-month lag. This would be the time lag necessary for resources to be incorporated in the biomass of the population of females. Resources consumed are incorporated as new tissue for growth and production of young, which take 8–10 months to become adults (S. M. Mendel, in litt.).

Litterfall seems to affect density and biomass of females more immediately than does precipitation. The delays of 1 and 2 months in the response of density and biomass of females after litterfall may result from the time lag between litterfall and the colonization of the litter by macroarthropods. These are the preferred food of D. aurita (Freitas et al. 1997; Santori et al. 1995). Litter decomposition follows a succession, taking time for a significant increase in macroarthropod biomass to occur (Garay 1988; Garay and Hafidi 1990). Additionally, D. aurita requires time to respond to the increase in biomass of macroarthropods.

Gentile et al. (2004), in a study carried out in the same area as our study, also observed a positive correlation between the density of D. aurita and litterfall, but with delays of 6 and 7 months. These authors used the trapping grids as the effective sampling area (0.64 ha), overestimating density, and analyzed data from only 2 years, from 1997 to 1999. The shorter time series and the less-accurate estimate of density could be the reasons for the longer lag in the peak of density after litterfall observed by Gentile et al. (2004). We calculated the effective sampling area based on the movement distance MaxDspool (Mendel and Vieira 2003). This method provided a more accurate and lower estimate of density, and the time series covered a period of almost 7 years, from 1997 to 2003. Consequently, it was possible to detect a shorter lag of only 1 or 2 months in the peak of density and biomass after litterfall.

The anticipation of litterfall relative to precipitation may be evidence of the long-term direct effect of rains on the soil and indirect effect on leaves. Just before the next wet season, trees drop old leaves while putting on new leaves. At this time, trees draw upon soil moisture reserves to have new foliage ready for the next growing season (Martins and Rodrigues 1999). This pattern also was observed by Morellato et al. (2000) in 2 Atlantic Forest formations, in Premontane Forest and in Coastal Plain Forest.

The analysis of population dynamics separately for each sex was fundamental for detection of the effects of precipitation and litterfall on the population of D. aurita. Precipitation and litterfall are major indications of resource availability for D. aurita, and affected mostly the density and biomass of females. The hypothesis that density was more variable than biomass was supported only for females. In addition, a significant multiannual trend of increasing density was detected only for females, and only biomass of females followed the biannual cycle observed for precipitation. Litterfall also affected density and biomass only of females. When studying population dynamics of small mammals, we recommend that analysis of density and biomass is performed separately for each sex. Major effects of environmental factors may go undetected if differences between sexes are ignored.

Acknowledgments

We are grateful to V. Rademaker and D. Loretto for their gracious concession of data on population dynamics and movement of D. aurita, and to the students of the Laboratório de Vertebrados, Universidade Federal do Rio de Janeiro, for their teamwork in the field and suggestions. I. Garay called our attention to the arthropod dynamics in the litter, and A. Marcondes and N. P. Barros gave technical and clerical support. Financial support was provided by Conselho Nacional de Desenvolvimento Científico e Tecnológico—Programa Apoio a Núcleos de Excelência (CNPq-PRONEX (661100/1997-7), Programa Institucional de Boisas de Iniciação Científica (PIBIC/CNPq), Fundação Universitária José Bonifácio (FUJB), and Conservação e Utilização Sustentável da Diversidade Biológica Brasileira (PROBIO [MMA-GEF]).

Literature Cited

.

2003

.

Nutritional and fiber contents of laboratory-established diets of neotropical opossums (Didelphimorphia, Didelphidae)

. Pp.

225

233

in

Predators with pouches: the biology of carnivorous marsupials

(, eds.).

CSIRO Publishing

,

Melbourne, Victoria, Australia

1994

.

Ecology of a small mammal community in an Atlantic Forest area in southeastern Brazil

.

Studies on Neotropical Fauna and Environment

29

:

197

217

.

.

2000

.

Population ecology and reproduction of the white-eared opossum Didelphis albiventris (Mammalia, Marsupialia) in an urban environment of Brazil

.

Ciência e Cultura

52

:

171

174

.

.

2001

.

Food habits, home range and activity of Didelphis aurita (Mammalia, Marsupialia) in a forest fragment of southern Brazil

.

Studies on Neotropical Fauna and Environment

36

:

85

92

.

.

1993

.

A five-year population study of an assemblage of small mammals in southeastern Brazil

.

Mammalia

57

:

507

517

.

et al. .

1981

.

Les mammifères frugivores arboricoles nocturnes d'une forêt Guyanaise: inter-relations plantes–animaux

.

Revue d'Ecologie la Terre et la Vie

35

:

341

435

.

.

2002

.

Survival in fluctuating bank vole populations: seasonal and yearly variations

.

Oikos

98

:

467

479

.

.

2003

.

A method to determine the minimum number of littertraps in litterfall studies

.

Biotropica

35

:

419

421

.

1998

.

Variação espacial e temporal na estrutura do habitat e preferência de microhabitat por pequenos mamíferos na Mata Atlântica

.

M.S. thesis

,

Museu Nacional da Universidade Federal do Rio de Janeiro

,

Rio de Janeiro, Rio de Janeiro, Brazil

().

.

1997

.

Habitat preference and food use by Metachirus nudicaudatus and Didelphis aurita (Marsupialia, Didelphidae) in a restinga forest at Rio de Janeiro, Brazil

.

Brazilian Journal of Biology

57

:

93

98

.

the Animal Care, Use Committee of the American Society of Mammalogists

.

2007

.

Guidelines of the American Society of Mammalogists for the use of wild mammals in research

.

Journal of Mammalogy

88

:

809

823

.

1988

.

Relations entre l'hétérogénéité des litières et l'organisation des peuplements d'arthropodes édaphiques

.

Ph.D. dissertation

,

Université Pierre et Marie Curie

,

Paris, France

.

.

1990

.

Study of a mixed forest litter of hornbeam (Carpinus betulus L.) and oak (Quereus sessiliflora Smith) III. Organization of the edaphic macroarthropod community as a function of litter quantity

.

Acta Ecologica Sinica

11

:

43

60

.

.

2000

.

Population dynamics and reproduction of marsupials and rodents in a Brazilian rural area: a five-year study

.

Studies on Neotropical Fauna and Environment

35

:

1

9

.

.

2004

.

Population dynamics of four marsupials and its relation to resource production in the Atlantic Forest in southeastern Brazil

.

Mammalia

68

:

109

119

.
Sours: https://academic.oup.com/jmammal/article/89/1/159/1020219
GIANT OPOSSUM! Possible World Record

I raised my head and looked piteously at Bogdan. My eyes filled with tears a little and my lips trembled, Bogdan pulled my chin to him and our lips closed again, oh Lord, how I adored when he kissed. And so he again fumbles in my mouth, searches him, gently but persistently, his hands began to squeeze my elastic ass, and his lips. Sucked, we forgot about everything in the world.

Only his tongue.

Now discussing:

Well, bitch, answer, when was the last time you fucked. - Oksanka repeated her question. The lady sobbed and lowered her head. Such a question was humiliating for Sholpan Damirovna, arrogant, arrogant and proud.



2245 2246 2247 2248 2249