La estrategia de forrajeo de alouatta palliata. Variaciones en la dieta y conducta alimenticia asociadas a la disponibilidad de alimentos (tamaño de hábitat y estacionalidad), y los efectos sobre su salud fisiológica

Zusammenfassung

RESUMEN: Habitat loss and fragmentation seriously threaten several howler monkey taxa, such as our study species, the critically endangered Mexican mantled howler monkey (Alouatta palliata mexicana). This situation requires us to determine the key elements that may promote the persistence of howler monkeys in forest fragments and to evaluate how changes in the availability of these elements may affect their future conservation prospects. The availability of fruit, big trees and figs (Ficus) have been suggested to be key resources for the persistence of howler monkeys in forest fragments. However, studies of the effects of the availability of these key resources on primate persistence are scarce, and it remains unclear how the use of these resources by primates varies with habitat characteristics, and the effects that this variation may have on their diet, activity and, ultimately, their fitness. This thesis examined how the availability of these key resources in two forest fragments in Los Tuxtlas, Mexico, was related to the diet, feeding effort and stress levels in two groups of A. p. mexicana. The results suggest that fruit, big trees and figs are all key elements promoting the persistence of howler monkeys in forest fragments. This is as both fruit consumption and food source size appear to be negatively related to feeding effort, while figs can provide fruit during periods of scarcity. Variations in feeding effort are probably important for howler monkeys, as feeding effort was found to be positively related to stress levels. However, female howler monkeys appear to be particularly sensitive to increases in feeding effort, which may explain the unusually low immature to female ratio found in the forest fragments of Los Tuxtlas. Overall, these results suggest that the reduction in key resources associated with forest fragmentation have negative effects on howler monkey health and fitness. As much of the remaining habitat of Mexican mantled howler monkeys is highly fragmented, these results are a significant concern for their future conservation prospects.