This issue: Summer 2016

Powers Publishes Landmark Findings on Heat Dissipation in Hummingbirds

Bruin Notes

Professor Don Powers

How do hummingbirds avoid overheating even as they beat their wings up to 70 times per second? Recently biology professor Don Powers and a group of colleagues set to find out.

Their findings, published in the journal Royal Society Open Science and publicized by the BBC, Science Online and several other media outlets, accomplished more than resolving an interesting scientific query. It provided valuable insight into the hummingbirds’ future as a pollinator amid possible climate change.

The answer became clear thanks to footage taken with Powers’ infrared thermal camera: The birds have three hot spots from which excess heat is expelled – around the eyes, under the wings, and on the feet. These “windows” for heat loss average 14.5 degrees warmer than the rest of the bird’s body surfaces. During hovering, their hottest activity, hummingbirds expand their eye spots and lower their feet to cool down.

“Understanding how they get rid of the massive amounts of extra heat they produce during flight is key to predictions of how birds will fare in the face of inevitable global warming,” Powers explains. “This could be particularly important for hummingbirds because they are key pollinators when they drink nectar from flowers. If climate change impedes their ability to forage, the result could be a decline in plant reproduction and substantial changes in ecosystem structure.”

The next step in Powers’ research is to investigate how effective this heat dissipation technique remains as temperatures increase.

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