The value of radio tracking in the study of neotropical rain forest monkeys.

Although radio tracking has been used increasingly in primate field studies over the past 15 years, some primatologists have been reluctant to use it. We present data that demonstrate benefits of radio tracking in the study of rain forest primates. Data were collected during an ecological study of Ateles geoffroyi and Cebus capucinus in hilly, dense rain forest habitat with poor visibility, in northeastern Costa Rica. We SHOW that radio tracking decreased search time for both species, which led to increased contact time and facilitated continuous data collection. Mean search time for both primate species was significantly reduced using radio tracking (Kruskal-Wallis Test, P < 0.05). Search times for both species increased at the end of the study, when the transmitters ceased functioning. These increased search times occurred despite high levels of familiarity with the ranging patterns of the animals. The rate of marking feeding trees increased significantly with radio tracking and decreased significantly when the radios failed (Kruskal-Wallis Test, P < 0.01). Other benefits of radio tracking include: finding animals far off trail, in dense vegetation, and in inclement weather; maintaining continuous contact with the animals, which allows for more complete knowledge of ranging and foraging patterns; and monitoring group and subgroup composition. © 1994 Wiley-Liss, Inc.