16. Pecaris – Temas
Alexine Keuroghlian, Donald P. Eaton, Tatiana P. Tavares De Freitas
Are peccaries sexually dimorphic?
Over the last 5 years, we captured a total of 233 white-lipped peccaries in the Nhecolandia region of the Pantanal. For each capture we determined the sex, placed it in an age class, measured weight, and documented the length of nine external biometric parameters (i.e. head-body length, shoulder height, tail, ear, neck circumference, etc.). Instead of 4 age class categories, based solely on tooth wear, we subdivided the individuals into 8 categories based both on tooth wear and eruption categories. Our data set on white-lipped peccary biometrics is the largest ever compiled for a wild population. We conducted 2 x 8 factorial ANOVAs to test if the biometrics differed among sexes and/or age categories. If an overall significant difference was detected among age categories, we conducted Bonferroni Pairwise comparisons to determine which classes differed from each other. Of the 233 white-lipped peccaries captured, 130 were females and 93 were males (sex ratio = 1.40F:1M). The age category most captured was age clss 2 (N = 57) followed by age class 4 (N = 43). As expected, all parameters were significantly different among age categories. However, except for neck circumference (P = 0.003), there were no significant differences between the sexes. The LSD post tests showed that weights and head-body lengths were significantly different between the younger age categories until class 2 or 2.5. After age class 2, the differences between the categories were not significant. The average weight for adult white-lipped peccaries (age classes = 2.0, N=161) was 31.34 kg (SD = 4.3), and average head-body length was 110 cm (SD = 5.5). Adult weights peaked at age class 3.5, mean = 34.5 kg (SD = 4.6), and declined slightly in the oldest age class (4). Differences among the sexes in terms of neck circumference emerged at age class 1.5 and continued until age class 3.5. The larger neck circumference in males may be due to documented differences in skull size or changes in musculature associated with reproductive behavior. Interestingly these differences disappear in the oldest age class possibly because of a reduction in reproductive activity.