Meeting Abstract
Migrant birds arrive on their breeding grounds as early as possible to initiate breeding, especially in the Arctic where the breeding season is short. However, the timing of this major life history event can be affected by adverse environmental conditions (e.g., temperature, storms, and snow cover) which are highly unpredictable across years. In response to stressful events in the Arctic, birds activate the hypothalamic-pituitary-adrenal (HPA) axis in order to modify physiology and behavior through the actions of corticosterone. The degree to which the HPA axis is activated is thought to be regulated by the interaction of energetic status and environmental conditions. Lapland longspur (Calcarius lapponicus) stress physiology and morphology (fat and mass) along with environmental conditions (temperature and percent snow cover) were investigated in the summers of 2011-2014 to understand organism-environment interactions. Over the duration of the four year study, snow melt occurred unseasonably late in 2013 which delayed spring arrival. In response to these harsh conditions in 2013, body condition and mass were reduced relative to other years and HPA axis activity was increased. In addition, in three of the four years snow storms occurred around the period of egg laying which also increased HPA axis activity in every year except for 2013. Interestingly, HPA axis activity in response to snow storms was dependent upon parental status. Pre-parental birds increased activity in HPA axis activity compared to parental birds. In conclusion, HPA axis activity in Lapland longspurs is highly plastic and adapts to environmental conditions and parental status to help individuals cope with unpredictable events.
