title: Do smart birds stress less? An interspecific relationship between brain size and corticosterone levels.
abstract: Vertebrates respond to unpredictable noxious environmental stimuli by increasing secretion of glucocorticoids (CORT). Although this hormonal stress response is adaptive, high levels of CORT may induce significant costs if stressful situations are frequent. Thus, alternative coping mechanisms that help buffer individuals against environmental stressors may be selected for when the costs of CORT levels are elevated. By allowing individuals to identify, anticipate and cope with the stressful circumstances, cognition may enable stress-specific behavioural coping. Although there is evidence that behavioural responses allow animals to cope with stressful situations, it is unclear whether or not cognition reduces investment in the neuroendocrine stress response. Here, we report that in birds, species with larger brains relative to their body size show lower baseline and peak CORT levels than species with smaller brains. This relationship is consistent across life-history stages, and cannot be accounted for by differences in life history and geographical latitude. Because a large brain is a major feature of birds that base their lifetime in learning new things, our results support the hypothesis that enhanced cognition represents a general alternative to the neuroendocrine stress response.
authors.affiliation: Department of Biology, Virginia Tech, , 4102 Derring Hall, Blacksburg, VA, USA, Department of Biology, College of Nyíregyháza, , Sóstói út 31/b, Nyíregyháza, Hungary, Department of Limnology, University of Pannonia, , Pf. 158, 8201 Veszprém, Hungary, Centre d'Études Biologiques de Chizé, Centre National de la Recherche Scientifique, , Villiers-en-Bois, 79360 Beauvoir sur Niort, France, CREAF, , Sciences Building, Cerdanyola del Vallès 08193, Spain, CSIC, , Cerdanyola del Vallès 08193, Spain.
authors.forename: Ádám Z
authors.initials: ÁZ
authors.lastname: Lendvai
authors.forename: Veronika
authors.initials: V
authors.lastname: Bókony
authors.forename: Frédéric
authors.initials: F
authors.lastname: Angelier
authors.forename: Olivier
authors.initials: O
authors.lastname: Chastel
authors.forename: Daniel
authors.initials: D
authors.lastname: Sol
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D001717:Birds / Q000033:anatomy & histology* / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology*; D003071:Cognition; D003345:Corticosterone / Q000378:metabolism*; D005938:Glucocorticoids / Q000378:metabolism*; D008954:Models, Biological
chemical_list: D005938:Glucocorticoids; D003345:Corticosterone
keywords: brain size; cognition; innovation; phylogenetic comparative analysis; stress response
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