Meeting Abstract
The regulation and use of energy stores are important elements of coping with environmental variation. Glucose is a common molecule involved in the use and storage of energy in vertebrates. Food limitation typically causes a decrease in glucose levels; however, under acute stress, circulating glucose levels can rise through gluconeogenesis, providing energy to help survive challenging conditions. Because of the effect of weather on energy availability and foraging efficiency, weather may influence glucose regulation; however, these dynamics remain poorly understood, particularly in birds. We tested the hypothesis that baseline glucose levels would be higher in free-living tree swallows (Tachycineta bicolor) experiencing challenging weather conditions. Specifically, we predicted that baseline glucose levels would be positively associated with temperature, and negatively associated with windspeed under non-acute starvation conditions. We also tested the hypothesis that the rapid glucose response to acute restraint stress would be higher in birds experiencing challenging weather conditions. Specifically, we predicted that 30-mintute post-capture glucose would be negatively associated with temperature, positively associated with windspeed, and negatively associated with measures of body condition and energy reserves (high body mass, low plasma β-hydroxybutyrate). We utilize multiple timescales of weather data to understand how free-living birds respond physiologically to variation in weather –a major source of challenging environmental conditions with which organisms must cope.
