title: Scared and less noisy: glucocorticoids are associated with alarm call entropy.
abstract: The nonlinearity and arousal hypothesis predicts that highly aroused mammals will produce nonlinear, noisy vocalizations. We tested this prediction by measuring faecal glucocorticoid metabolites (GCMs) in adult yellow-bellied marmots (Marmota flaviventris), and asking if variation in GCMs was positively correlated with Wiener entropy-a measure of noise. Contrary to our prediction, we found a significant negative relationship: marmots with more faecal GCMs produced calls with less noise than those with lower levels of GCMs. A previous study suggested that glucocorticoids modulate the probability that a marmot will emit a call. This study suggests that, like some other species, calls emitted from highly aroused individuals are less noisy. Glucocorticoids thus play an important, yet underappreciated role, in alarm call production.
authors: Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA. marmots@ucla.edu
authors: Daniel T
authors: DT
authors: Blumstein
authors: Yvonne Y
authors: YY
authors: Chi
mesh_terms: D000818:Animals; D003120:Colorado; D019277:Entropy; D005243:Feces / Q000737:chemistry; D005260:Female; D005938:Glucocorticoids / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008392:Marmota / Q000378:metabolism / Q000502:physiology*; D011863:Radioimmunoassay; D013312:Stress, Physiological; D014828:Vocalization, Animal
chemical_list: D005938:Glucocorticoids