Behavior is the first line of defense against stress. If you get too hot, you can move to shade, take off clothing, or turn on a fan. These behaviors either slow warming or speed cooling to bring you back toward an ideal temperature. But behaviors aren’t free. For instance, seeking shade might require you to spend time indoors when you’d rather be outside. And everyone knows that fans require electricity, which can add to your utility bill. In the same way, other animals pay for the behaviors that they use to thermoregulate.
We can think about three costs of behavior: energy, risk, and opportunity. Energetic costs are fairly straightforward. Animals that shuttle between sun and shade use energy to move. Birds and mammals use even more energy to generate metabolic heat. Risk arises when a behavior draws the attention of a predator. Just imagine how visible an animal is when basking in a bright open spot! Opportunity costs are usually the least obvious. But think about the concept like this: if you must rest in the shade or bask in the sun, you can’t search for food, water, or mates. Animals must balance the costs and benefits of their actions when thermoregulating.
Here’s what makes this problem interesting: an animal’s best decision depends on what other animals have decided. In other words, each animal is part of game whose outcome depends on every player’s behavior. If all of the females decide to spend their in the shade, breeding males should probably stay there as well. If all of the predators decide to hunt in the open, their prey should probably hide in the shade. By analyzing these games mathematically, we can predict how an animal should behave in a world filled with competitors, predators, and prey.
The thermal landscape is the chess board on which animals play their games. The outcome of a game depends on the structure of this landscape. Patchy landscapes enable inferior competitors or vulnerable prey to thermoregulate, whereas clumped landscapes do not. Patchiness enables an animal to access sun or shade wherever it spends its time. When a large male chases a small male from its territory, the small male can still find places to heat or cool. Likewise, patchy landscapes enable an animal to thermoregulate while avoiding the predators. We have conducted experiments in thermal arenas to establish these important lessons about behavioral games.
This research has been sponsored by the National Science Foundation.
Want to learn more? Read our recent publications about thermoregulation:
Buckley, L. B., J. C. Ehrenberger, and M. J. Angilletta. 2015. Thermoregulatory behavior limits local adaptation of thermal niches and confers sensitivity to climate change. Functional Ecology 29: 1038-1047.
Sears, M. W. and M. J. Angilletta. 2015. Costs and benefits of thermoregulation revisited: both spatial and statistical distributions of temperature drive costs. The American Naturalist 185: E94-E102.
Angilletta, M. J., M. W. Sears, and R. M. Pringle. 2009. The spatial dynamics of nesting behavior: lizards shift microhabitats to construct nests with beneficial thermal properties. Ecology 90: 2933-2939.