The stress response is attenuated during inclement weather in parental, but not in pre-parental, Lapland longspurs (Calcarius lapponicus) breeding in the Low Arctic

Jesse S Krause,Jonathan H Pérez,Helen E Chmura,Simone L Meddle,Kathleen E Hunt,Laura Gough,Natalie Boelman,John C Wingfield

doi:10.1016/j.yhbeh.2016.05.018

Abstract

Birds breeding at high latitudes can be faced with extreme weather events throughout the breeding season. In response to environmental perturbations, vertebrates activate the hypothalamic-pituitary-adrenal (HPA) axis and synthesize corticosterone, which promotes changes in behavior and physiology to help the animal survive. The parental care hypothesis suggests that the HPA axis activity should be downregulated during the parental stage of breeding to prevent nest abandonment. However, it is unknown what happens to HPA axis activity in response to severe weather at the transition from the pre-parental to parental stages of breeding. We sampled baseline corticosterone levels and the time course of corticosterone elevation over 60min of restraint stress and assessed body condition and fat stores in Lapland longspurs (Calcarius lapponicus) breeding in the Low Arctic in the presence and absence of snowstorms. The results showed that during the pre-parental stage, HPA axis activity was up-regulated in response to snowstorms, with corticosterone levels continuing to increase through 60min of restraint. However, once birds were parental, HPA axis activity was unaffected by snowstorms and levels peaked at 10min. Fat levels and body condition did not change in response to snowstorms but fat levels declined in males during the pre-parental stage. These data suggest that the parental care hypothesis can be applied to severe storm events; parental birds restrained the activity of the HPA axis, likely to focus on the reproductive effort that is already underway, while pre-parental birds greatly upregulated HPA axis activity in response to snowstorms to maximize self-preservation.

Highlights

Arctic breeding birds are faced with a short breeding season in which they have a single opportunity to raise a brood
In response to these severe weather events, we predicted based on the parental care hypothesis that pre-parental birds should adopt the “leave it” strategy in which adrenal responsiveness is enhanced while parental birds should adopt the “take it” strategy and reduce adrenal responsiveness
The activity of the HPA axis is plastic depending upon life history stage, parental status and environmental conditions

Summary

Introduction

Arctic breeding birds are faced with a short breeding season in which they have a single opportunity to raise a brood. J.S. Krause et al / Hormones and Behavior 83 (2016) 68–74 exposure to acute restraint stress evoke similar elevations in corticosterone within a life history stage in the absence of severe perturbations (Cockrem and Silverin, 2002, Ouyang et al, 2011, Cockrem, 2013). Multiple species, including Lapland longspurs (Calcarius lapponicus), can modify HPA axis activity within a life history stage in response to severe weather as shown through increases in baseline concentrations of corticosterone (Wingfield et al, 1983, Rogers et al, 1993, Smith et al, 1994, Astheimer et al, 1995, Romero et al, 2000, Raouf et al, 2006, Spée et al, 2010). The Lapland Longspur is an ideal study species as it breeds in the Arctic and so is exposed to inclement weather and it is has been subject of many endocrine studies over the last 2 decades

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