Collaborative Research: Is behavior on the front-line of solving the problem of inescapable heat? Leveraging intraspecific variation in a cavity-nesting bird thriving in heat

Intensifying heatwaves and rising temperatures pose unprecedented challenges – globally and throughout the United States – generating an urgent need to understand how at least some animals cope well with heat. Behavior is often key to resilience during environmental change, and yet we do not understand the capacity of behavior to resolve the problem of heat.

To address this fundamental question, this research tests a ‘behavior-centric’ framework to generate critical data on behavioral responses to increased temperatures. We challenge free-living birds with increased temperatures, focusing on a species whose numbers are increasing in the hot and humid southeastern United States. This research has high potential to open new areas of inquiry.

We will provide the basic research needed to inform future applied work, such as predictive models and conservation decisions. By focusing on behavior, we will build and test a framework that can be applied across species or across multiple anthropogenic insults that assail the natural world – wildfire smoke, endocrine disrupting chemicals, urban noise, and more.

By coupling this research with outreach and training, we will build educational infrastructure on the problem of heat, improve STEM training, and broaden participation for groups under-represented in STEM. Outreach products will include new infographics, installations, and virtual reality/gaming experiences that build understanding on the role of behavior in a changing world.

Altogether, results will give much-needed insight into how behavior does (or does not) buffer animals from the consequences of heat.

Biologists have long considered behavior to be the first line of defense against environmental change, and yet we lack key behavioral parameters for predicting who persists or succumbs to the growing challenge of heat. Small endotherms are particularly vulnerable and their early life conditions set the stage for lifetime fitness, yet we do not know much about how heat affects their relatively helpless young, who have limited options for coping.

To identify how behavior may buffer the effects of inescapable heat, this research will: (1) use cross-fostering to identify causes and consequences of among-individual variation in behavioral responses to heat, (2) determine how behavioral acclimation affects responses to subsequent heat, and (3) determine how populations vary in their behavioral capacity to mitigate heat. The study species is a cavity-nesting bird (Tachycineta bicolor), which is thriving in some warming environments.

The experimental challenge uses air-activated heat-packs in their enclosed nest cavity. The working hypotheses are that: individuals and populations vary in the degree to which behavior is effective at mitigating heat; and, recent experience and evolutionary history will shape whether behavioral responses are sufficient for coping with heat. Together with analyses of the fitness-related consequence of heat, these experiments will identify the relevance of behavioral variation within an individual, among individuals, and among populations.

In doing so, this research provides a cohesive test of the hypothesis that behavior truly is on the front line of solving the global challenge of heat.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.