Cuniculus paca (Linnaeus, 1766)

Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Cuniculidae, Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona: Lynx Edicions, pp. 398-404 : 404

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Lowland Paca

Cuniculus paca

French: Paca des plaines / German: Tieflandpaka / Spanish: Paca de llanura

Other common names: Paca, Spotted Paca

Taxonomy. Mus paca Linnaeus, 1766 ,

“Brasilia [= Brazil], Guiana.” Restricted by N. Hollister in 1913 to “French Guiana.”

Several subspecies are traditionally recognized, however, a recent review on the family Cuniculidae argues that a study that confirms the validity of these subspecies and establishes their geographical distribution 1s needed. In addition, another recent study on the phylogeography of South American populations did not find geographical differences. The distributions of South American subspecies are not well delimited so the ranges described here are tentative. Five subspecies recognized.

Subspecies and Distribution.

C. p. paca Linnaeus, 1766 — E & S Colombia, Venezuela, the Guianas, and E Brazil to Paraguay, N Argentina (Misiones and Corrientes provinces), and Uruguay.

C. p. guanta Lonnberg, 1921 — W Brazil, Ecuador, Peru, and N Bolivia.

C. p. mexianae Hagmann, 1908 — E Brazil, mouth of the Amazon in Para State.

C. p. nelsoni Goldman, 1913 — E & S Mexico (Atlantic slope lowlands from San Luis Potosi State to Yucatan Peninsula), then through Central America to N Costa Rica.

C. p. virgatus Bangs, 1902 — W Costa Rica, through Panama to N & W Colombia. It is also naturally present in Trinidad and Tobago Is (subspecies unknown), but it was extinct in Tobago I long ago due to overexploitation by Amerindians. They also introduced the Lowland Paca (nominate subspecies) from Venezuela into Curacao I, the largest of the Netherlands Antilles. In the 20" century it was successfully introduced into Cuba from Mexico, so it should belong to the Mexican subspecies nelson.

Descriptive notes. Head-body 500-774 mm, tail 13-35 mm, shoulder height 270-310 mm, ear 43-56 mm, hindfoot 113-130 mm; weight 5-14 kg. Male Lowland Pacas are 15% larger than females. Color of dorsal fur varies from reddish brown to dark brown or smoky gray and is marked with rows of white spots on sides; under parts are white. Head is almost square, marked bythick, fleshy lips; elaborate nares; large, light brown eyes; prominent stiff rostral vibrissae up to 150 mm in length; and tufts of vibrissae below ears and behind eyes. Dental formula is I 1/1, Co0/0,P1/1,M 3/3 (x2) =20.

Habitat. All types of mature and disturbed multi-strata tropical humid and dry forests, and sometimes mangrove habitat, near rivers, lagoons, or creeks from sea level to elevations of about 2000 m. Lowland Pacas sometimesvisit open field habitats, including cultivated fields. They often prefer mature vegetation near water, such as gallery forests, where fruit production is high and rivers or creeks provide escape from predators.

Food and Feeding. [.owland Pacas mainly eat fruit and supplement their diets with seeds, leaves, bark, and cultivated crops. Available information suggests that Lowland Pacas do not discriminate among fruits; across their distribution, they are generalist frugivores, and diets contain ofa great variety offruits depending on season and local availabilities. Among the eleven or more plant families in the Lowland Paca’s diet, the palm family Areaceae appears to be very important. The Lowland Paca eats ripe fruits that have fallen from trees. It seems to prefer almost the same soft fruits that bats eat, and these fruits are highly seasonal, becoming less available in the late rainy season and early dry season. Some fruit species are available at all times of the year, allowing the Lowland Paca to be primarily frugivorous. The frugivorous—folivorous diet influences basal metabolic rate ofthe Lowland Paca , which is 119% ofthe value expected from its body mass. The Lowland Paca is a 9kg caviomorph rodent that eats 290 g dry weight of food/day, or 9 kg/ month. It mostly feeds alone although there are some observations of two individuals feeding together, sometimes two adults and sometimes an adult female with her young. Lowland Pacas cannot manipulate and open hard-shelled fruits and do not store food. The Lowland Paca “stores” food in the form offat to deal with seasonal food scarcity. Sound of falling fruits attracts Lowland Pacas, which allows them to find fruits on the ground. They like to eat in the darkest possible place, and they carry fruits and seeds to sheltered feeding spots. Lowland Pacas practice coprophagy; they eat some of their own feces. They seem to be important short-distance seed dispersers in Neotropical forest ecosystems and probably seed predators of some plant species.

Breeding. The Lowland Paca has a low reproductive rate, provides long-term care of young, and is long-lived. Based on information from wild and captive Lowland Pacas, females reach maturity at 8-12 months of age, with body masses of 8-10 kg; males are mature at c.12 months, with body masses of 9-12 kg. The Lowland Paca is polyestrous, and its reproductive success seems to be associated with quality and quantity of food availability. Estrous period is 10-42 days, and gestation is 85-173 days. About 80% offemales give birth to theirfirst offspring at 8-21 months old. Births occur throughout the year, with some females giving birth once a year (28-60%) and others twice (31-71%). Times between multiple births in a single year are 97-268 days, but it is c.466 days for females that have a single birth per year. Littersize is mainly one young (95-100%); twins or triplets are rare (1-5%). Head-bodylengths and body masses of newborn Lowland Pacas are 334 mm and 606-764 g for females and 333 mm and 708-737 g for males,respectively. Average sex ratio at birth is c¢.1-3:1 (¢.56% males and 44% females). Newborns are precocial; they are born with hair and an adult appearance, open eyes, erupted incisors, and cheekteeth appearing through gums. Female Pacas have four mammas, rarely six. Lactation in captivitylasts ¢.84 days and in the wild, c.42 days, until newborn weighs 1-2 kg. At the end oflactation, newborns also eat fruit that the mother chewed for them. By 6-9 months of age, juveniles are 6-8 kg. They tend to remain with their mother for c.12 months. The Lowland Paca can live to c.12 years in the wild and 16-3 years in captivity. Mating of Lowland Pacas occurs throughout the year, but there seems to be periodicity in mating, with most females pregnant or giving birth in February-May and September—December. During courtship, a male Lowland Paca approaches a female, urinates on her, and walks around her making strong growls and gridding his teeth. The female might try to avoid the approaching male and occasionally attack him. The male approaches her, at an angle, and then turns and tries to urinate on her. Usually, the female tries to avoid the spray. The male keeps repeating this behavior until he finally

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Subspecies and Distribution. C. p. paca Linnaeus, 1766 — E & S Colombia, Venezuela, the Guianas, and E Brazil to Paraguay, N Argentina (Misiones and Corrientes provinces), and Uruguay. C. p. guanta Lonnberg, 1921 — W Brazil, Ecuador, Peru, and N Bolivia. C. p. mexianae Hagmann, 1908 — E Brazil, mouth of the Amazon in Para State. C. p. nelsoni Goldman, 1913 — E & S Mexico (Atlantic slope lowlands from San Luis Potosi State to Yucatan Peninsula), then through Central America to N Costa Rica. C. p. virgatus Bangs, 1902 — W Costa Rica, through Panama to N & W Colombia. It is also naturally present in Trinidad and Tobago Is (subspecies unknown), but it was extinct in Tobago I long ago due to overexploitation by Amerindians. They also introduced the Lowland Paca (nominate subspecies) from Venezuela into Curacao I, the largest of the Netherlands Antilles. In the 20" century it was successfully introduced into Cuba from Mexico, so it should belong to the Mexican subspecies nelson.