In the later part of spring, there was a hot weekend where the temperature got up to around 90 degrees Fahrenheit. It was the first day of the year where it had become that hot and it felt like summer had suddenly arrived in a blast of heat. I felt a bit drained from the surge in temperature and was staying in the shade as I walked around the arboretum. I was at the beginning of the zigzag trail when I heard a robin alarming on the hillside and went to check it out. I found two great horned owls—a parent and a juvenile. They were briefly on the same branch together and then the parent flew a little ways down the hillside. The juvenile stayed behind and I could see that it was eating a northern flicker. As it sat on the branch, it was occasionally making a screeching call that seemed to be a begging communication to the parent and to me, a possible signal that it was uncomfortable in the heat.
To remedy the stress from the heat It was perched in the deep shade of the hillside where it was coolest. It was also cooling itself by holding its wings open to allow the air to circulate over its body. I could also see that it was holding its mouth open and vibrating its neck. Some birds will perform a version of avian panting called gular fluttering where they open their mouths and vibrate their neck muscles to try and remove excess heat. Basically, opening their mouth and fluttering their neck muscles (in the throat or “gular” region) increases blood flow and moves air across the moist membranes in their mouth and esophagus, resulting in evaporative cooling.
As the daytime highs are consistently rising into the 90’s, I recommend fluttering your feet around in the river. Stay cool everybody. I hope to see you out there!
Resources
How Birds Keep Their Cool | Audubon. 1 Aug. 2012, https://www.audubon.org/news/how-birds-keep-their-cool.
How Do Birds Keep Cool in the Summer? | U.S. Fish & Wildlife Service. 11 Jun. 2021, https://www.fws.gov/story/how-do-birds-keep-cool-summer.