Glucocorticoid levels in free ranging resident mantled howlers: a study of coping strategies

Abstract

A growing amount of data shows that a preference for passive-nonaggressive over active-aggressive problem solving is associated with higher levels of glucocorticoids (GC). For mantled howlers, the arrival of an adult male in a new group is a potential source of psychological stress for both resident males and females. Resident mantled howler males take an active stand and aggressively repel the entrance of solitary males, while females take a passive-nonaggressive stand. In order to study whether the relationship between coping strategies and the activation of the hypothalamic-pituitary-adrenal (HPA) axis observed in other species applies to the response of resident mantled howlers to the presence of solitary males, we examine the relationship between different group and subpopulation variables and the GC levels measured in feces collected from 10 groups living in six forest fragments, in Los Tuxtlas, Mexico. The results of our study suggest that the resident mantled howler females' passive response to the presence of solitary males is accompanied by the activation of the HPA axis, whereas resident males' aggressive response is not accompanied by any changes in the HPA axis. In contrast, a previous study suggests that resident male howlers respond by increasing their testosterone levels to the presence of solitary males (Cristobal-Azkarate et al., Hormones and Behavior 2006;49 261-267). These different behavioral and hormonal responses coincide with the active and passive coping styles described for other species. The conditions in which howlers live in our study area may be favoring the interaction between solitary and resident howlers, and inducing chronically high GC levels, which in turn could negatively affect the fitness of these subpopulations.

Endocrinology of Howler Monkeys: Review and Directions for Future Research

“…Nonetheless, mean male fecal androgen levels per group were positively correlated with the number of extragroup males living in the same forest fragment, suggesting that mantled howler males on average exhibited a hormonal response proportional to the potential threat posed by solitary males (Cristóbal-Azkarate et al 2006 ). Fecal glucocorticoid levels averaged across all sampled males per group were not signifi cantly correlated, while those averaged across all sampled females per group were positively correlated with the number of solitary males living in the same forest fragment (Cristóbal-Azkarate et al 2007 ). The authors suggested that differences in the ways in which males and females cope with stressful, unpredictable situations posed by the presence of extragroup males in their forest fragment may account for different mean fecal glucocorticoid levels among resident males and females.…”

“…Finally, comparison of glucocorticoid levels between males and females has revealed that females of mantled howler monkeys appear to be more sensitive than males to either social (e.g., threat of extragroup males in habitat; Cristóbal-Azkarate et al 2007 ) or ecological stressors (e.g., translocation and human handling; AguilarCucurachi et al 2010 ), information that could only have been identifi ed by combining behavioral observations with endocrine studies.…”

“…The authors suggested that differences in the ways in which males and females cope with stressful, unpredictable situations posed by the presence of extragroup males in their forest fragment may account for different mean fecal glucocorticoid levels among resident males and females. The passive response displayed by resident mantled howler females towards solitary males might be associated with an activation of the hypothalamic-pituitary-adrenal (HPA) axis resulting in chronically elevated fecal glucocorticoid levels, whereas the more active and aggressive response displayed by resident males seemed not to be associated with the activation of the HPA axis resulting in lower fecal glucocorticoid levels (Cristóbal-Azkarate et al 2007 ), similar to differential glucocorticoid levels associated with passive versus active coping styles in captive rodents (Koolhaas et al 1999 ;Ebner et al 2005 ).…”

Variation in the extraction efficiency of estradiol and progesterone in moist and lyophilized feces of the black howler monkey (Alouatta pigra): alternative methods

“…Some research methods used for hormone extraction are based on the selection of a solvent, the application of temperature (Gao and Liu, 2005), the types and time of agitation, using moist feces (Heistermann et al, 1996; Wasser et al, 2000; Hunt and Wasser, 2003; Hunt et al, 2004; Cristóbal-Azkarate et al, 2007) nor lyophilized feces (Wasser et al, 1997, 2004; Goymann et al, 1999; Khan et al, 2002; Hunt et al, 2004) from diverse species of mammals. Also in these studies include the evaluation of free ligand activity added to the substratum and validation of the assay (Buchanan and Goldsmith, 2004; Palme et al, 2005).…”

Stress in Wildlife Species: Noninvasive Monitoring of Glucocorticoids

“…Using these techniques, the effect of stressful situations like forest fragmentation in the habitat of Alouatta pigra monkeys [8] , or how a group of Alouatta palliata species solve stressful problems created for example by the arrival of a new male to a resident group [9] have been published. Influences on fecal cortisol of environmental conditions such as forest conservation have been recently reported in free-living Yucatan spider monkeys [10] .…”