Miller & Gidley 1918
Paca (Cuniculus) is a genus of ground dwelling, herbivorous rodents in South and Central America. It is the only genus in the family Cuniculidae. They are large rodents with dots and stripes on their sides, short ears, and a barely visible tail.
The Smithsonian Tropical Research Institute in Panama has studied the possibilities of developing the Paca as a viable high-priced food supply for the tropics.
Evolutionary background 
Pacas originated in South America and are one of the few mammal species that successfully emigrated to North America after the Great American Interchange . They were formerly grouped with the agoutis in the family Dasyproctidae, subfamily Agoutinae, but were given full family status because they differ in the number of toes, the shape of the skull, and in patterning.
50–77 cm (20–30 in) in length, excluding the 13–23 cm (5.1–9.1 in) short tail, pacas weight 6–14 kg (13–31 lb) and are the third and fourth largest rodents. Similar to guinea pigs, they have square heads, small ears, sides patterned with spots and stripes, and a virtually non-visible tail.
With large hindlimbs, small forelimbs, and a cone-shaped body, the pacas are similar in appearance to the deer-like, ungulate chevrotains, and like them have four to seven horizontal lines of blotches and stripes along its flanks. They have a heavy and robust appearance, though their legs are long and relatively tiny. Their small ears are set high on the head. They have four toes on the forefoot and five on the hindfoot (of which two a short and hardly touch the ground) and they have stout nails that resemble small hooves. In young pacas, the skin is covered with horny scales about 2 mm (0.079 in) in diameter; perhaps these scales have a protective function against smaller predators. There is virtually no differences between sexes. They can live up to 13 years in the wild.
Pacas inhabit rainforests, cloud forests, and sometimes more open habitats. They are great swimmers and prefer to be near water. They dive when threatened and can stay submerged up to 15 minutes. They can also jump up to 1 m (3 ft 3 in) and freeze up to 45 minutes. They normally move along well-established paths and will create new paths when old ones are disturbed.
They are normally passive in daytime and forage in the morning and afternoon, but can be strictly nocturnal in areas with many predators. They live in burrows up to 3 m (9.8 ft) deep, normally with two entrances covered with leaves to hide the burrow and to serve as an early warning system. Burrows are often near water but always above the seasonal flood line. Predators except humans includes jaguar, puma, ocelot, margay, jagarundi, bush dog, boa constrictor, and caiman.
Pacas have resonating chambers in their cheeks and their growling noise, at about 1 kHz, is surprisingly loud for their size. Aside from making noises, territories are marked with urine. Population density can reach up to 70 adults per 0.2 km2 (0.077 sq mi) and pacas often constitute some 20% of the biomass of terrestrial mammals.
In the wild, pacas eat fruits from understory trees and fallen fruits from taller trees, but can also eat leaves, buds, flowers, fungi, and insects. They play a vital role as seed dispersal and, with seasonal adaptations, their home ranges is often centred on a group of fruit trees. Pacas normally do not use their forepaws to manipulate fruits (as do agoutis), instead using their powerful jaw muscles to break open hard-shelled fruits. Unlike agoutis, pacas can store fat and therefore are less dependent of caching seeds. Competition from agoutis is avoided by a slight variation in activity cycles and food preferences. Like rabbits, pacas are coprophagous and absorb protein and carbohydrates from specially produced moist fecal pellets. Before allowing their young to suckle, mothers lick them to stimulate them to defecate and urinate, and then licks the resulting product, both to feed herself and to prevent the odour from attracting predators.
Gestation lasts between 114-119 days with about 190 days between births. Pacas are precocial, new born are born with fur and open eyes. Normally mothers give birth to one individual per litter, but she can produce up to three litters per year if conditions allow. More than one litter per year results in lactation periods overlapping pregnancies. Weaning begins after six weeks, but the young start to follow their mother early and can do so for up to a year.
Sexual maturity is reached after 6-12 months when females weigh 6.5 kg (14 lb) and males 7.5 kg (17 lb). Pacas usually mate in water. As the male approaches the female, she starts to hop enthusiastically, more so if he sprays her with urine. Pacas have altered the common rodent strategy — safety in numbers — and mind their offspring carefully. 650–710 g (23–25 oz) at birth, the youngs are born in holes too small for both predators and the mother to enter, which are then covered with leaves and twigs. To invite the youngs out of the hole, the mother uses a low rolling vocalization. Suckling usually lasts for 90 days after which the young weights 4 kg (8.8 lb).
Distribution and habitat 
The Lowland paca is found from southern Mexico to northern Argentina. They primarily live in rainforests near streams, but can also be found in a wide variety of habitats, including mangrove swamps, gallery forests near water currents, and even in public parks. They have been observed up to 2,500 m (8,200 ft) above sea level.
The Mountain Paca has longer and darker fur than the Lowland Paca. Observations indicate that Mountain Pacas are found between 1,500–2,800 m (4,900–9,200 ft) above sea level.
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