Temperate winters can impose severe conditions on songbirds that threaten survival, including shorter days and often lower temperature and food availability. One well-studied mechanism by which songbirds cope with such conditions is seasonal acclimatization of thermal metabolic traits, with strong evidence for both preparative and responsive changes in thermogenic capacity (i.e., the ability to generate heat) to low winter temperature. However, a bird's ability to cope with seasonal extremes or unpredictable events is likely dependent on a combination of behavioral and physiological traits that function to maintain allostatic balance. The ability to cope with reduced food availability may be an important component of organismal response to temperate winters in songbirds. Here we compare responses to experimentally reduced food availability at different times of year in captive red crossbills (Loxia curvirostra) and pine siskins (Spinus pinus) – two species that cope with variable food resources and live in cold places – to investigate seasonal changes in the organismal response to food availability. Further, red crossbills are known to use social information to improve response to reduced food availability, so we also examine whether use of social information in this context varies seasonally in this species. We find that pine siskins and red crossbills lose less body mass during time-restricted feedings in late winter compared to summer, and that red crossbills further benefit from social information gathered from observing other food-restricted red crossbills in both seasons. Observed changes in body mass were only partially explained by seasonal differences in food intake. Our results demonstrate seasonal acclimation to food stress and social information use across seasons in a controlled captive environment and highlight the importance of considering diverse physiological systems (e.g., thermogenic, metabolic, digestive, etc) to understand organismal responses to environmental challenges.

These data were collected in an experimental, repeated measures design across multiple different experiments. Experiments were identical in their food restriction methodology but were performed with different individuals and in different years. We use this database to compare seasonal differences in food intake and change in body mass during food restriction in captive finches - the red crossbill and pine siskin. Food was restricted by limiting the access to food cups to two 45-minute feeding sessions per day. We also compare seasonal differences in food intake and change in body mass during food restriction between red crossbills with and without predictive social information from food-restricted neighbors. The data deposited here are raw scores of food intake and body mass for each individual in the experiment across three days of food restriction. Some birds were housed as dyads and some individually. For dyads we calcualted food intake as the change in the mass of the food cup divided by two. Only one food intake score per pair was included in analysis of food intake, although the a food intake value is provided in this database for every individual.