We have not had a cold winter (so far) but we have still had a lot of nights with temperatures below freezing. How do these beautiful little birds manage to survive?
It is thought that Anna’s Hummingbirds are able to winter so far north because their diets contain a larger proportion of insects and arachnids than most hummingbirds. Not only do these bugs provide nutrients during the winter when there are few flowers blooming, but they also provide a slower-metabolizing source of food which may help them survive the long nights. Anna’s Hummingbirds have a fairly large body weight for a hummingbird which may also help them.
One other key point is that hummingbirds are able to survive the cold nights through their ability to induce a torpid state called daily torpor or noctivation. For more information on the torpid state.
Thanks to Dee-Ann Leblanc for bringing the information on noctivation to our attention.
Photos: An Anna’s (is is a female or a juvenile?) at a heated feeder in Garibaldi Highlands.