Hormone - Behavior Adaptations for Breeding at High Latitudes

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Little is understood of how environmental and social factors, particularly territorial aggression, affect the breeding of migratory arctic birds. Relationships between reproduction and environmental induced stress, where they play an important adaptive role, are virtually unknown in high latitude species. Many species arrive in the arctic,establish territories and eventually feed their nestlings in a fraction of the time for temperate birds. Adherence to this rigorous schedule, pairs must ignore environmental conditions that would normally inhibit or delay breeding at temperate latitudes. Dr. Wingfield proposes that these constraints have been met by adaptations of the endocrine system in arctic birds. This study proposes to continue examining the relationship between two potentially antagonistic hormones: corticosterone, which directs behavior away from reproductive activities and towards survival activities and testosterone, which mediates the aggressive behavior associated with territoriality. In both hormone-behavior systems, Dr. Wingfield suggests that the endocrine responses of arctic-nesting birds will show decrease sensitivity to environmental stimuli, allowing more prolonged opportunities to breed. The endocrine adaptations to be investigated in this research program may elucidate physiological mechanisms by which polar animals avoid delays and/or conflicting behaviors which might reduce their chances for successful reproduction.