Darkness and rainfall prevail during Pacific Northwestern winters and this year has been no exception. More than four inches of rain fell during a 48-hour period this week. Following this two-day deluge, the air smelled dank and musty like a giant worm bin. It’s hard for humans to endure this gloomy foul weather, let alone birds that have to survive outdoors — especially some that only weigh a few ounces.
Feathers are key. Their structure, design and maintenance enable birds to survive most stretches of cold and rainy weather. Bird feathers are water resistant; rain hits the surface of the bird and rolls away without being absorbed. Further, when rain is heavy, birds flatten their feathers to make them even more water-resistant.
Bird feathers have masterfully evolved to provide insulation. Barbs and barbules hook together to form tiny, loose tangles that trap air and heat while at the same time providing strength and suppleness. People who wear down “puffy” jackets appreciate this warmth. As Thor Hanson said in his masterpiece Feathers “With their intricate air-trapping microstructure, down feathers are the most naturally insulative material on earth, and birds have the ability to fluff them up manually, essentially adjusting their R-value at will.”
In heavy rain, notice how birds adopt a posture with their bodies upright and heads withdrawn with their beaks pointed toward the incoming weather. This allows them to conserve energy and reduces the penetration of the rain. You can also observe how often birds preen their feathers. They do so by reaching their bills into oil glands and applying that oil on to their feathers. The oil is the necessary ingredient that makes the feathers supple and water-resistant.
Some birds, like Anna’s Hummingbirds, chickadees and titmice are able to thermally-regulate to adapt to cold and wet periods. Anna’s Hummingbirds enter a state of torpor when outside temperatures drop. Other species like chickadees, kinglets and titmice do something similar called facultative hypothermia which also entails lowering their body temperatures temporarily to reduce heat loss and save energy.
Birding can be unproductive during rain storms because birds perch or hunker down instead of flying around. Since stormy weather generally occurs during barometric low-pressure periods, it is harder for birds to fly. Birds prefer dense air that provides an aerodynamic lift to fly. Falling rain and high humidity further reduce the density of the air making flight difficult. Birds can and will fly short distances in rain but their wings eventually become saturated with water making it harder to fly.
Despite all of these adaptations, birds still get hypothermia and can die during extreme cold and rainy periods. Having bird feeders helps them get through these stretches. The abundance of birds on our feeders in the winter is testimony to their need for food supplements to help them cope with cold and wet conditions.
Meanwhile here in Seattle, the rain has temporarily ceased. Birds are mobbing our feeders, flying around, calling and engaging in territorial scraps. Miraculously, most have survived another epic storm.
Bird Note – National Public Radio program “Why Do Birds Avoid Flying in the Rain?” – July 10, 2017
So, when it rains, where do birds go to find cover? Out to lunch, or not. In to huddle with some buddies, or not. Everything is dependent upon the environment, the rain, and the bird.
We now present to you, as a special bonus section of our post on birds and rain, birds and a very different kind of rain.
I’ve been meaning to write about this topic for a while—now xkcd has beaten me to it:
Wilson G, Cooper S, Gessaman J. 2004. The impact of artificial rain and temperature on the metabolism of Falco sparverius, or American kestrels, Comparative Biochemistry and Physiology, Part A. 139(3):389-394.
In the field, I’ve noticed that although birds may initially vanish when it rains, they eventually begin to reappear. They must continue foraging because they have chicks to feed.
During periods of intense precipitation, observe how birds assume an erect stance, retracting their heads and pointing their beaks towards the approaching weather. This lessens the amount of rain that gets in and enables them to save energy. You can also observe how often birds preen their feathers. They accomplish this by inserting their bills into oil glands and dousing their feathers in the oil. The oil is what gives the feathers their suppleness and water resistance.
Meanwhile here in Seattle, the rain has temporarily ceased. Birds are swarming our bird feeders, circling, making calls, and squabbling over territory. Miraculously, most have survived another epic storm.
Bird Note – July 10, 2017 – National Public Radio program “Why Do Birds Avoid Flying in the Rain?”
Feathers are key. Because of their construction, upkeep, and design, birds can withstand most periods of cold and precipitation. Because bird feathers are waterproof, raindrops that land on their surface simply roll off without getting absorbed. Moreover, birds flatten their feathers to increase their water resistance during periods of heavy rain.
Certain birds, such as titmice, chickadees, and Anna’s hummingbirds, can adjust their body temperature to cope with cold and moisture. Anna’s Hummingbirds go into a state of torpor when the weather gets cold. Similar behavior known as facultative hypothermia is displayed by other species, such as chickadees, kinglets, and titmice. This behavior involves lowering body temperature momentarily in order to prevent heat loss and conserve energy.
FAQ
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