Wed, Aug 17, 2022: 5:00 PM-6:30 PM
ESA Exhibit Hall
Background/Question/MethodsSeasonal environments impose on animals the necessity to balance their energy expenditure and energy gain according to fluctuating environmental conditions. For species wintering in temperate and polar regions, however, the wintering period can remain an energetically challenging period with deterioration in weather conditions, temperature or food quality creating an “energetic bottleneck” in their annual life cycle. Using 11 years of continuous geolocation tracking data (fall 2008 to spring 2019), we estimated the locations and daily energy expenditure of black-legged kittiwakes (Rissa tridactyla) throughout the non-breeding period. To do so, we estimated a time-activity budget and used species-specific basal and field metabolic rates for flying, foraging and resting behaviours. We expected that individuals differing in winter space utilization must face different environmental constraints and modulate their foraging effort accordingly.
Results/ConclusionsTracking results indicate that kittiwake winter distribution is spread across the North Atlantic Ocean from the North American to European coasts, but that most individuals spent winter west of the Mid-Atlantic Ridge. However, this area was associated with higher daily energy expenditure driven by more time spent flying in the West than in the East. We also found that individuals extending their stay in the Barents Sea during autumn were able to adjust to a shorter daylight duration by prolonging their foraging and flying activity into the night. Differences in winter movement strategies thus led to variations in the energy budget, with individuals modulating their behaviour to a certain degree. Overall, the ability of individuals to maintain their energy balance has consequences on life history traits, like mortality or reproductive potential, which ultimately shape population dynamics and selects for migratory behaviour to avoid difficult winter conditions.
Results/ConclusionsTracking results indicate that kittiwake winter distribution is spread across the North Atlantic Ocean from the North American to European coasts, but that most individuals spent winter west of the Mid-Atlantic Ridge. However, this area was associated with higher daily energy expenditure driven by more time spent flying in the West than in the East. We also found that individuals extending their stay in the Barents Sea during autumn were able to adjust to a shorter daylight duration by prolonging their foraging and flying activity into the night. Differences in winter movement strategies thus led to variations in the energy budget, with individuals modulating their behaviour to a certain degree. Overall, the ability of individuals to maintain their energy balance has consequences on life history traits, like mortality or reproductive potential, which ultimately shape population dynamics and selects for migratory behaviour to avoid difficult winter conditions.