Stress and the costs of extra-territorial movement in a social carnivore

Abstract

Costs associated with extra-territorial movement are believed to have favoured the evolution of delayed dispersal and sociality across a range of social vertebrates, but remain surprisingly poorly understood. Here we reveal a novel mechanism that may contribute substantially to the costs of extra-territorial movement: physiological stress. We show that subordinate male meerkats, Suricata suricatta , exhibit markedly elevated faecal glucocorticoid metabolite levels (a non-invasive measure of hypothalamic–pituitary–adrenal axis activity) while conducting extra-territorial prospecting forays. While brief increases in glucocorticoid levels are unlikely to be costly, chronic elevations, arising from prolonged and/or frequent forays, are expected to compromise fitness through their diverse negative effects on health. Our findings strongly suggest that prolonged extra-territorial movements do result in chronic stress, as the high glucocorticoid levels of prospectors do not diminish on longer forays and are no lower among males with greater prospecting experience. A generalized ‘stress’ of extra-territorial movement may therefore have strengthened selection for delayed dispersal and sociality in this and other species, and favoured the conduct of brief forays over extended periods of floating. Our findings have implications too for understanding the rank-related distribution of physiological stress in animal societies, as extra-territorial movements are often conducted solely by subordinates.

Adrenal activity in maned wolves is higher on farmlands and park boundaries than within protected areas

“…There have been only a few such studies conducted in free-ranging carnivores. One example is the work of Young and Monfort [61] who have demonstrated that prolonged extraterritorial movement in subordinate meerkats (Suricata suricatta) markedly elevates glucocorticoid metabolites that, in turn, compromises fitness and health. An investigation of African wild dogs (Lycaon pictus) that were captured from nature and held in enclosures for 22 weeks has revealed an abrupt rise in excreted glucocorticoids followed by a decline of hormone concentration to baseline level within 2 weeks of being in captivity [11].…”

“…This presents distinct advantages (over urine) for case of collecting specimens. Specifically and depending on species specificities, fecal corticoid concentrations and patterns have reflected changes or differences in carnivore social status (African wild dog [12], gray wolves [Canis lupus, [50]], spotted hyena [Crocuta crocuta, [18], meerkat [61]), acclimation to new territory post-translocation (African wild dog [11]) and reaction to increased human activities in native habitat (gray wolf [13], spotted hyena [58]). …”

Noninvasive Monitoring of Fecal Cortisol Metabolites in the Eastern Chipmunk (Tamias striatus): Validation and Comparison of Two Enzyme Immunoassays

“…Immunoassays originally designed to target native (i.e., nonmetabolized) glucocorticoids have been extensively used to quantify fecal glucocorticoid metabolites in an array of species (Harper and Austad 2000;Wasser et al 2000;Young and Monfort 2009). These assays assume that the antibody has sufficient cross-reactivity to recognize (a group of) metabolites of the parent hormone and that an increase in blood glucocorticoid secretion leads to an increase in metabolite excretion in the feces.…”

“…Although these assays have different cross-reactivities and hence different efficacy, they have been used with success to study relationships between fecal glucocorticoid metabolite levels and some aspects of the reproduction or the ecology of the animals in their natural environment (Jurke et al 1997;Lynch et al 2002;Mateo 2007;Young and Monfort 2009). Other studies use antibodies designed to recognize a group of fecal glucocorticoid metabolites sharing a common structure (Jurke et al 1997;Lynch et al 2002;Möstl and Palme 2002;Möstl et al 2005;Mateo 2007;Young and Monfort 2009). These metabolite antibodies typically yield higher concentrations of measured metabolites and display a higher reactivity with the fecal glucocorticoid metabolites than antibodies targeting native glucocorticoids and are therefore more likely to detect small fluctuations in fecal glucocorticoid metabolites (Morrow et al 2002;Frigerio et al 2004).…”

Examining disease prevalence for species of conservation concern using non‐invasive spatial capture–recapture techniques

“…; Thorn et al . ), and be used to develop basic ethograms of animal behaviours (Young & Monfort ). These non‐invasive survey techniques, such as photographic surveys, and survey designs such as distance sampling have also enabled scientists to quantify both mortality and recruitment rates in wildlife populations, even for rare and elusive species (Marucco et al .…”