title: An experimental test of the capture-restraint protocol for estimating the acute stress response.
abstract: Stress-induced increases in glucocorticoids (GCs) modulate behavior and are key in directing energy reserves. The capture-restraint protocol was developed to experimentally stimulate and quantify the magnitude of the acute stress response by comparing baseline GC levels with those collected after restraining a subject for a period of time, typically 30 min. This protocol has been used extensively in the field and lab, yet few studies have investigated whether it parallels hypothalamic-pituitary-adrenal (HPA) activation under natural acute stressors. We examined the hypothesis that acute stress from the capture-restraint protocol accurately mimics the adrenocortical response induced by a natural acute stressor. Using wild-caught rock pigeons Columba livia in a repeated-measures design, we compared plasma corticosterone (CORT) concentrations at baseline, after exposure to acute capture-restraint (30 min in a cloth bag), after tethering in a harness (30 min), and after a real but nonlethal attack by a predatory raptor. As found in previous studies, the capture-restraint treatment significantly increased CORT levels of pigeons compared with baseline. However, we also found that when pigeons were exposed to an attack by a raptor, their CORT levels were more than twice as high compared with the capture-restraint treatment. Our results provide evidence that an authentic acute stressor can activate the HPA axis to a greater extent than the capture-restraint protocol and also suggest that real predation attempts can have a significant effect on acute stress levels of wild birds.
authors: Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada.
authors: Jesse J
authors: JJ
authors: Pakkala
authors: D Ryan
authors: DR
authors: Norris
authors: Amy E M
authors: AE
authors: Newman
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D010856:Columbidae / Q000502:physiology*; D003345:Corticosterone / Q000097:blood*; D005260:Female; D020387:Food Chain; D005938:Glucocorticoids / Q000097:blood*; D046428:Hawks / Q000502:physiology; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D008297:Male; D010827:Physiology / Q000379:methods*; D010913:Pituitary-Adrenal System / Q000502:physiology; D011235:Predatory Behavior; D011863:Radioimmunoassay; D012149:Restraint, Physical / Q000379:methods*; D013312:Stress, Physiological; D013997:Time Factors
chemical_list: D005938:Glucocorticoids; D003345:Corticosterone