Caluromys philander (Linnaeus, 1758)

Russell A. Mittermeier & Don E. Wilson, 2015, Didelphidae, Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona: Lynx Edicions, pp. 129-186 : 132-133

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Caluromys philander


4. View Plate 8: Didelphidae

Bare-tailed Woolly Opossum

Caluromys philander

French: Opossum jaune / German: Gelbe Wollbeutelratte / Spanish: Raposa lanuda oriental

Taxonomy. Didelphis philander Linnaeus, 1758 ,

“America.” Restricted by O. Thomas in 1911 to “ Surinam.”

There is strong morphologic and morphometric evidence that the form dichurus may represent a separate taxon; it shows clear morphometric differences with little or no overlap with all others. Morphometric analyses of Venezuelan specimens also suggest that the form trinitatis should be treated as a separate species. Four species recognized.

Subspecies and Distribution.




C. p. trinitatis Thomas, 1894 — Venezuela (N of the Orinoco River) and Trinidad I. View Figure

Descriptive notes. Head-body 16-279 cm, tail 25-40.5 cm; weight 140-390 g. Dorsal fur of the Bare-tailed Woolly Opossum is uniformly pale brown to buffy or warm reddish-brown, sometimes mixed with gray. This color extends onto sides of body and limbs. Head is gray or grayish, with a dark brown mid-rostral stripe and brown eyerings. Tail length is ¢.150% of head-body length, and tail has fur only on its proximal 10-20% ofits length. Naked rest oftail is usually brown, sometimes mottled with paler markings. Ventral fur is orange or pale orange, and fur is dense and soft, varying across populations found at different elevations;it tends to be shorter at lower elevations and longer at higher ones. Feet are pale gray or whitish, and ears are pale brown, with yellow fur at their bases. As in the two other species of the genus, and unlike any other species of opossums, eyes are rich brown, with black, round pupils. Females lack a complete pouch; they have an “intermediate” pouch consisting of deep lateral abdominal skin folds that are more developed when pouch young are present. Females have seven mammae, one median mamma and three on each side. The Bare-tailed Woolly Opossum has a 2n = 14, FN = 24 karyotype, with all biarmed autosomes and with a small acrocentric X-chromosome and a small biarmed Y-chromosome. An FN = 20, with two acrocentric autosomal pairs, from specimens from north-eastern and south-eastern Brazil has also been reported. Skull size and shape are sexually dimorphic.

Habitat. Tropical lowland forests to at least 1600 m in elevation. Bare-tailed Woolly Opossums are found in primary and secondary lowland or lower montane forests, but they are apparently more abundant in secondary forests, usually occupying higher strata of forest and canopy, at heights above 10 m. Although there are some records of Bare-tailed Woolly Opossums occurring in dry forests in Bolivia and in the caatinga, they are almost always associated with humid habitats. They apparently thrive in disturbed vegetation and may occupy buildings that are near or in forests, nesting under roofs; they have been captured in yards, pastures, and cultivated areas.

Food and Feeding. Along with Derby’s Woolly Opossum ( Caluromys derbianus ) and the Brown-eared Woolly Opossum ( Caluromys lanatus ), the Bare-tailed Woolly Opossum is commonly considered to be among the most frugivorous opossum. In fact, it is one of the few well-studied opossum species when it comes to diet. Its diet includes a high proportion of fruits (as determined by presence of seeds in feces): seeds can account for 90% of the volume in fecal samples in Atlantic Forest and cerrado sites. This proportion can vary (although remaining high) in othersites, such as French Guiana forests where it is ¢.75%. Number of plant species identified in its diet varies considerably, 8-28 species in differentsites, and includes genera Astrocaryum ( Arecaceae ), Cecropia ( Urticaceae ), Ficus ( Moraceae ), Inga ( Fabaceae ), and Passiflora ( Passifloraceae ). Plants eaten always include species rich in carbohydrates, fat, and water. Baretailed Woolly Opossums, like all opossums, also consume high levels of invertebrates, although this may vary geographically and depend on availability of preferred food items. In Atlantic Forest sites, consumed invertebrates include Coleoptera, Hymenoptera, Arachnida, Orthoptera, Lepidoptera, Hemiptera, and Diptera . Invertebrates are present in 26% of the same feces as fruit seeds and represent most of the remaining 10% in volume in Atlantic Forest sites. In contrast, cerrado populations seem to have a more variable diet, directly influenced by clear variation in resource availability, with higher consumption of arthropods during the dry season and higher fruit consumption in the rainy season when species of Clidemia and Miconia (both Melastomataceae ), Mpyrcia ( Myrtaceae ), and Vismia (Hypericaeae) are consumed. The Bare-tailed Woolly Opossum can be considered an important disperser of seeds of several riparian forest species in the Brazilian cerrado. Its diet can also include other plant items, such as nectar from flowers of Couepia (Chrysobalaneceae), Hymenaea , Inga (both Fabaceae ), and Ravenala ( Strelitziaceae ), and it may therefore act as a pollinator for these species (although sometimesit eats whole flowers). It sometimes also eats tree gum from Fagara ( Rutaceae ) trees. Eating habits of Bare-tailed Woolly Opossums vary with reproductive state; females increase their food intake during late lactation to cope with high nutritional requirements of feeding growing young. As a consequence, increase in food intakeis directly related to total litter size at weaning; females with largerlitters increase their intake more than females with smaller litters. Nutritional contents of preferred diets, determined with cafeteria experiments in captivity where individuals were free to choose food items according to their needs, resulted in 0-64 g of proteins, 8-2 g of carbohydrates, 0-1 g oflipids, and 2-7% offibers per 100 g of dry matter.

Breeding. Nests of Bare-tailed Woolly Opossums are made with dead leavesin tree cavities, palms, or tangled lianas. As with most species of opossums, leaves are carried to the nest in a tight pack with the tail. They also readily use artificial nest boxes as dens (by males and females) and nests; five of 16 females found using nest boxes during a five-year population study in an Atlantic Forest reserve in south-eastern Brazil had pouch young. Sexual maturity of the Bare-tailed Woolly Opossum is reached at c.10 months, and gestation is long compared with other opossum species,lasting at least 21 days, with records of 20-28 days in captive individuals. After they are born, neonates remain attached to the teats for 75-80 days,after which they are left in the nest for the first time. They then spend 30-45 days in the nest, until they are totally weaned. They disperse c.130 days of age. In French Guiana, mean litter size is 4-1 young, varying from two to seven young. Litters of six young on average were reported from Venezuela, and litters varied from two to four young in south-eastern Brazil; females from central Brazil were collected with litters of three young. Variations in litter size within a site at different times or across localities are related to availability of food,type of forest (secondary or primary forest), and age or body mass of the female. Up to three litters per year can be produced if resources are abundant, and a single litter can occur in periods of resource scarcity. Due to the high nutritional requirements oflactation and the finite amount of energy the nursing mother can transfer, young born in smaller litters (1-3 young) are usually larger when weaned than those born in large litters (6-7 young). Breeding season in south-eastern Brazil has been estimated to be October-December, but breeding occurs all year long in French Guiana.

Activity patterns. Bare-tailed Woolly Opossums are strictly nocturnal. In French Guiana, they begin their activities right after sunset. Duration of foraging is directly linked to sex, reproductive state, and resource availability. When resources are abundant, females with small pouch young are mostly active during the first one-half of the night, but if resources are scarcer, they may forage almost all night. Females with larger young are active almost all night. Males are more active than females, remaining active during most of the night, and their nighttime activities apparently are not only related to food searches but also locating females. Differences in duration of foraging activities seem to vary across populations because shorter or longer activity periods related to reproductive status or resource availability were not observed at othersites in the same country. Bare-tailed Woolly Opossums do not decrease their activity when it is raining, but they are much less active during the brightest phases of the moon than during the darker nights of the month. Because females are usually less active than males, moonlight has more influence on the activity patterns of males than on those of females.

Movements, Home range and Social organization. Bare-tailed Woolly Opossums are apparently solitary. Although several individuals can be seen foraging in the same tree, they avoid close contact. When several males are kept together in captivity, however, they establish dominance—submissive relationships, even if there are no females housed with them. After established, these relationships are maintained for as long as the individuals are housed together, but competition increases in the presence of females. Bare-tailed Woolly Opossums are highly arboreal, foraging mainly in the canopy, and are usually captured at heights of 5-12 m in Atlantic Forest and Brazilian and French Guiana Amazonian sites. They are trapped almost exclusively in understory or canopy traps and seldom on the ground. They are able to move across gaps by bridging and jumping and can walk on fine branches. Home range estimates vary considerably, depending on whether they are established during studies that use trapping grids or radio-telemetry. Estimated home ranges for Bare-tailed Woolly Opossums in southeastern Brazil were 2-5-7 ha; estimates varied from 0-75 ha (0-3-1-7 ha) to 2:4—4-3 ha and reached up to 8:9 ha in different areas in French Guiana (all based on radiotelemetry data). Home ranges of males overlapped with those of females and those of other males. Home ranges are more evenly distributed during the dry season when resources are scarcer. An individual Bare-tailed Woolly Opossum uses on average 1-1 ha of its home range each night, traveling 500-1000 m. Densities of Bare-tailed Woolly Opossums in French Guiana were 50-143 ind/km?, with higher estimates reaching 200 ind/km?. In Venezuela, densities reach a maximum of 80 ind/km?.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Although the Bare-tailed Woolly Opossum may be affected locally by deforestation because it is highly arboreal,it is widely distributed, populations are presumably large, it occurs in many protected areas throughout its distribution, and it survives well in disturbed vegetation. As an arboreal species, it would be expected that it would be directly affected by fragmentation, but populations living in Atlantic Forest fragments in south-eastern Brazil use both edge and interiors of fragments, and they also likely use surrounding non-forested matrix for foraging.

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Caluromys philander

Russell A. Mittermeier & Don E. Wilson 2015

Didelphis philander

Linnaeus 1758