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A New Attachment Device for Radio-Collars in Collared Peccaries in Tropical Rainforests

Isa Mariela Torrealba Suarez, Jaime Ricardo Rau Acuna, Wildlife Management and Conservation Program (PRMVS), Universidad Nacional, Apdo. 1350-3000, Heredia, Costa Rica, and Jhonny Villareal Orias, Universidad de Los Lagos, Lab. de Ecologia, Casilla 933, Osorno, Chile

Among the free ranging ungulates of the Nearctic and the Neotropics, the collared peccary, Tayassu tajacu (Tayassuidae), is one of the most important game species for rural hunters. However, it has been mostly studied in the northern arid part of its geographical range (SW USA to N Argentina); in Latin America there is little information on its nutritional and behavioral ecology, especially in home-range usage and activity patterns, among other descriptive ecological parameters in lowland tropical-humid-forests.

After the establishment of the La Selva Biological Station in 1968, a tropical rainforest isolate (1,500 ha) surrounded by farmlands and connected by a highland corridor with the Braulio Carrillo National Park (+40,000 ha) in NE Costa Rica, an apparent increase in peccary numbers was observed. In 1992, peasants living outside the reserve claimed that peccary herds were creating a detrimental effect on their crops. Peccaries are shy, run fast inside the forest and, moreover, those environments are dark and have heavy rainfall ­ aspects which make their study difficult. Ecological research on collared peccaries was begun in 1992 in order to assess peccary home range sizes, diurnal activity patterns, herd and population size estimation, diet, consumption, and damage to crop plants. For this particular presentation, we have emphasized technical aspects: the attachment method and its possible consequences on instrumented peccaries.

A total of 25 peccaries from 3 herds were captured. After all were able to rid themselves of the neck-collars, we had to make some technical decisions in order to guarantee the success of our investigation. Although no papers have been published on instrumenting peccaries, communications with other peccary researchers indicated that collar loss and catching a front leg inside collars were common problems. As implanted radios were too expensive and thought to be useless in tropical rainforests, we decided to try a harness. Many investigators have noticed that after attaching a transmitter to an animal there is an adaptation period during which the animals may alter their behaviors. Our hope was to design a harness that could make for a more secure attachment method, long enough to surpass that acclimation period.

The low-success method consisted of the radio-collars alone (MOD400 and MOD500, Telonics, AZ, USA). In 1992 we captured 17 peccaries and instrumented six of them. The others were marked temporarily after taking the standardized measurements and weighed. These six animals were able to rid themselves of the collars between 4 and 6 weeks after being instrumented. One of them caught a front leg inside the collar and we recaptured him, released his leg, and let him go without the collar. On another occasion the collar was found in a Ficus root deformity, which the animal probably used to help rid himself of the collar.

In 1993, we made a breast-harness with nylon ribbon and instrumented 5 peccaries. This high-success method (same radio-collars as above but with temporal harnesses) let us radio-track animals for >6 months. However, again, two of the animals caught a front leg inside the collar (one 26 and another 34 days after capture). We recaptured those animals, released their legs, evaluated their general condition, and left them with the collars and the harnesses in place. On the second month one of the animals (the largest captured male) was able to rid himself of the harness but kept the collar (47 days after capture). During the fourth month none of the peccaries had harnesses but did have radio-collars in place. The ribbon had less life-expectancy than the collars, but its actual life was long enough to allow peccaries to surpass the acclimation period.

We were able to successfully collect data on monthly and annual home-range sizes, activity patterns, density and group size, diet, consumption and damage to crop plants. We suggest radio-tracking collared peccaries in rainforests with harnesses; if possible, to construct a harness with more life-expectancy; and to follow the instrumented peccaries carefully during the adaptation period (first 5 or 6 weeks after capture) in order to detect as soon as possible when animals could have caught a front leg inside the collars.

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