The species of mammal that is most likely to be seen by visitors to BCI is the agouti or neque. A visitor does not need to walk in the forest to see agoutis because many live in the laboratory clearing and are easily approached. Along forest trails they are readily seen feeding on Pseudobombax flowers (*shaving brushes*) and gnawing noisily on nuts. Agoutis are usually diurnal, but many stay up after sunset in the lighted areas around the buildings. On the mainland in Balboa they are commonly active at night on the town streets. In areas where they are hunted, they tend to wait until dusk before appearing.
Agoutis weigh about 3 kg, are reddish or yellowish brown in color, with dainty deer-like legs and big rumps. They have long hairs on their rumps and very tiny tails. When alarmed or involved in territorial conflicts, they can raise the hairs on the rump until they stand out straight. Agoutis grunt and bark softly, thumping their hind feet rhythmically when challenging territorial opponents. A male may thump on a hollow log. They often jump while running from a predator and make loud barking noises. Agoutis live on the forest floor, and usually occupy burrows on hillsides or in hollow logs and brushpiles.
Dr. William Glanz recorded 36 species of fruits that he observed agoutis eating. They feed on fallen fruits and flowers and are especially fond of the large, hard-shelled seeds of Dipteryx, Astrocaryum, and sometimes Scheelea. They have difficulty gnawing the Scheelea nuts but often pick up fruits that are partially opened by squirrels. These hard seeds are also hoarded by burial in scattered locations within their territories, and the supply helps tide them over in periods of fruit shortages. This habit of seed burial is important for the dispersal of seeds of many plants.
One pair of adult agoutis on BCI will occupy an area of about 2 hectares. Agoutis are territorial and monogamous, defending their territories very vigorously from other agoutis in times of fruit shortage. A female agouti may have up to three litters in a year and may live 2.5 years on the average. Males live somewhat shorter lives. Agoutis may give birth at any time of the year, but most young are born between March and July. The one or two young are placed in their own burrows, and are called out for nursing when the mother visits. Young live in these burrows for 8 to 9 weeks. If food is plentiful, mothers may nurse the young for another 2 months; but if food is scarce, they are left to forage on their own. The details of their life cycle were revealed by the studies of Dr. Nicholas Smythe on BCI. He was one of the first researchers to clearly show the effects of severe seasonal fruit shortages on the populations and adaptations of mammals on BCI.
The greatest mortality is among the young agoutis, usually because they fail to establish territories, and therefore do not obtain sufficient food. They may weaken from poor nutrition and then are more easily preyed on than healthy animals. They are eaten by cats, snakes, birds of prey, and tayras. Humans hunt agoutis for meat and often reduce their numbers severely in areas where hunting occurs.
© Jacalyn Giacalone, Ph.D. 1997