howler monkey eating in a tree

Brocket Deer

by Jacalyn Giacalone, Ph.D. and Gregory E. Willis

Posted in: Mammal Directory, Rainforest Connection Live

One of the most elegant mammal species on BCI is the Red Brocket Deer, which has slender legs, long grey neck, big dark eyes, mobile pink ears, and a rich red-brown body. They can be distinguished from white-tailed deer (Odocoileus virginianus), which used to occur on BCI, because brockets are only about two-thirds the size of a white-tail, have a proportionately large rump that rises in a curved back (white-tails have flat spines), and their tails form small, round powder puffs (also white) rather than the long flag of a white-tail. Brockets also do not have the white markings around the nose and eyes that white-tails do. In both species the males have antlers that are shed each year. Brocket antlers are simple, straight spikes only a few inches long, but white-tails in Panama also often have straight spikes, not the large racks of their northern counterparts.

Brockets are well-adapted to rainforest life. They have straight antlers and small bodies (24 – 48 kg) for sliding under and through tangled vines, they have a habit of freezing when startled and then slipping away into dense vegetation, and they are solitary in their foraging. The white-tails on BCI were never very numerous and seemed to confine their activities to the forest edges and the very open parts of the plateau, where they could run rapidly to avoid predators. Their scats, tracks, and actual sightings dwindled in frequency in the early 1990*s, and we think there are no more white-tails on BCI. Of course, some could swim from the mainland again, but the forest is now even less suitable for white-tails than ever before: they usually favor second growth and edges.

Brockets can be seen on BCI in the late afternoon around the edges of the lab clearing, and at almost any time on any trail. It helps to walk quietly and slowly, and look for brockets under flowering or fruiting trees. Early morning is the best time, or at dusk. The early and middle afternoon are not good times to try to see them, but they can be active 24 hours a day on BCI. They often walk along the trails or lie down beside the trails, chewing cud or sleeping. At night they can be spotted with a headlamp. Their eyeshines are bright yellow and may be low to the ground if they are resting. Their tracks look like very tiny white-tail tracks, and can be confused with those of peccaries.

Brocket adaptations also include a complex stomach that provides chambers for the fermentation of coarse vegetation by symbiotic bacteria. This is the same sort of process that enables cows to eat grass. Both species must regurgitate their food and chew it again as *cud* in order to fully process the food for its maximal nutritional value. They must spend much of their day resting while they chew the cud. This ability to digest thoroughly and to use bacteria for the process makes it possible for brockets to thrive on a diet of leaves, flowers, buds, fruit, and fungi that would not support most other species. We have followed brockets on BCI who became accustomed to our presence and we were able to record 17 different species of leaves, flowers, fruits, shoots, and seedlings that were fed on during several sessions from January to March. This was only a small part of their diet, since much of what they consumed could not be identified.

Young are born at any time of the year. They are tiny fawns with white spots usually in rows along their sides. Mothers leave their young hidden in undergrowth where they are very well camouflaged while the mother forages. Researchers walking off the trails sometimes find fawns accidentally by nearly stepping on one. A startled fawn will run very rapidly a short distance and then drop down again into the leaf litter, tucking its head to curl up, and hopefully to disappear into the background. Fawns should be left alone so that they do not become exhausted trying to escape. The mother will eventually return to feed her fawn.

Brockets are often seen in pairs, as a male and female usually inhabit the same territory. Boundaries are marked by bucks rubbing their antlers on slender vertical woody stems and by scraping the soil and urinating. They produce a loud sneezing snort when alarmed and stamp their front feet.

A brocket is called corzo in Panama, while a white-tail is called venado cola blanca. Both are highly sought-after for their meat. In many places they have been over-exploited by uncontrolled hunting and are severely reduced in numbers.

© Jacalyn Giacalone and Gregory E. Willis, 1997