do birds like getting wet

I’ve been meaning to write about this topic for a while—now xkcd has beaten me to it:

Oh, well. Since the comic doesn’t actually answer the question, I’m hoping you’re all still interested! (Also, at the end there will be a bonus discussion of ant rain. Yes, ant rain. You won’t find that on xkcd!)

You’ll notice I’ve changed the question a bit from the xkcd comic: where Randall Munroe asks “Where do birds go?” I’d like to answer “What do birds do?”—because birds don’t necessarily go anywhere when it rains.

Rain poses two major possible dangers to a bird. The biggest one is hypothermia: birds stay warm by trapping tiny pockets of air under their feathers, and if those pockets fill with water instead of air, that bird is going to get cold very quickly. (This is why down jackets don’t work when wet.) American Kestrels exposed to rain increase their metabolic rate, presumably to compensate for heat loss (Wilson et al. 2004).

The smaller the bird, the bigger a problem this is, since smaller birds have higher surface-area-to-volume ratios, meaning they lose heat more quickly, and they generally have smaller energy reserves.

Already you can see how avian responses to rain might depend on the bird: small birds might seek out shelter more readily than large birds, to avoid getting wet and cold. Indeed, while smaller birds sought shelter during one torrential rain, a flock of Turkey Vultures was seen perched at the tops of tree with wings spread, rain-bathing (Hume 1986).

Birds can and do take shelter from rain: in bushes, in reeds, under eaves, in nesting cavities. But this is necessarily a short-term solution, because birds also need to eat. This is the second possible danger of rain: starvation. You can hide from an afternoon shower, but a week-long downpour is not something you can wait out, especially if you’re a small bird without much stored energy. You’re going to have to eat, and to do that, you’ll have to get wet.

(If you haven’t already, check out the videos of hummingbirds flying in heavy rain at the end of this older post.)

I’ve seen this in the field: birds may briefly disappear when rain first starts, but if it lasts any length of time, the birds start to reappear. They can’t afford to stop foraging—especially if they have chicks to feed.

Length isn’t the only aspect of rain that matters—intensity makes a difference too. A sufficiently light rain probably won’t be a problem. Most bird feathers are somewhat water resistant, and in light rain, you may see birds fluffed up, just as they would in a dry cold.

Heavy rain calls for a different tactic. Fluffing up your feathers keeps you warm, but if the rain is heavy enough, water will get in between your fluffed-up feathers and chill you faster. Instead, in heavy rains birds sleek down their feathers to reduce their wettability.

The classic bird-in-heavy-rain posture, as described by Hume (1986), is “head withdrawn, bill pointed towards the rain, body rather upright and feathers sleeked,” a pose which combines staying warm (“head withdrawn” is a heat-conserving position), minimum exposure of the bird to rain, and maximum opportunity for raindrops to slide off the feathers rather than being absorbed. Birds may take up this posture when they don’t have access to shelter. Shorebirds in the rain have been observed huddled close together, all in this posture (Hume 1986).

So where do birds go in the rain? To shelter, or not. Out to lunch, or not. In to huddle with some buddies, or not. It all depends on the bird, the rain, and the environment.

And now, in a special bonus part of our birds-and-rain-themed post, we bring you: birds and a completely different kind of rain.

Ant rain is a phenomenon in the tropics where ants climb up trees to forage and then, while most of them climb back down, some of them jump or fall down, forming “ant rain.” Haemig (1997) reports that this “continuous rain of free-falling ants” is affected by birds: when birds forage in a tree full of ants, the ants try to escape by jumping, and the ant rain increases.

Next time there’s an awkward lull in conversation, you can whip out that factoid and impress everybody. You’re welcome.

Haemig P. 1997. Effects of birds on the intensity of ant rain: a terrestrial form of invertebrate drift. Animal Behaviour 54:89-97.

Wilson G, Cooper S, Gessaman J. 2004. The effects of temperature and artificial rain on the metabolism of American kestrels (Falco sparverius). Comparative Biochemistry and Physiology, Part A. 139(3):389-394.

*Photos obtained from Flickr and used via Creative Commons. Many thanks to these photographers for using Creative Commons!

*Photos obtained from Flickr and used via Creative Commons. Many thanks to these photographers for using Creative Commons!.

Rain poses two major possible dangers to a bird. The most common is hypothermia; birds trap tiny air pockets beneath their feathers to stay warm; if those pockets fill with water instead of air, the bird will become very cold very quickly. (This is why down jackets don’t work when wet. Rain-exposed American Kestrels raise their metabolic rate, possibly to make up for lost heat (Wilson et al. 2004).

This is more of an issue for smaller birds because they typically have lower energy reserves and higher surface-area-to-volume ratios, which cause them to lose heat more quickly.

In the tropics, a phenomenon known as “ant rain” occurs when ants climb trees to gather food, and while the majority of them descend again, some of them fall or jump, creating the illusion of “ant rain.” According to Haemig (1997), birds have an impact on this “continuous rain of free-falling ants” because when birds forage in an ant colony, the ants attempt to flee by jumping, which causes the ant rain to increase.

Birds can and do seek cover from the rain in nesting cavities, bushes, reeds, and under eaves. However, since birds also require food, this is only a temporary fix. This is the second possible danger of rain: starvation. A week-long downpour is something you cannot wait out, especially if you are a small bird with little energy reserves. You can hide from an afternoon shower. You will need to consume food, which will require getting wet.

Therefore, during a storm, many birds perch to save energy rather than flying. They sit it out under the cover of a tree. Alternatively, they can perch on a fence wire facing the wind to lessen air resistance and prevent as much of their valuable body heat from being lost. However, after the storm blows through, birds start to soar again.

Storms change the air, which is the medium through which flight occurs. Rainstorms tend to occur when atmospheric pressure is low. Air in a low-pressure system is less dense. However, the aerodynamic lift required for birds to take flight is provided by dense air. A lot of water molecules are also released into the atmosphere by falling rain and high humidity. The air is less dense because of the space that the water occupies in it.

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Sounds of birds provided by Cornell Lab of Ornithology, Ithaca, New York’s Macaulay Library of Natural Sounds #16 Thunderstorm Nature Sound Essentials and #47 Deciduous Forest Morning recorded by Gordon Hempton. Nancy Rumbel and John Kessler composed and performed the theme music for BirdNote.

This audio story is brought to you by BirdNote, a partner of The National Audubon Society. BirdNote episodes air daily on public radio stations nationwide.

FAQ

What happens if birds get wet?

Rain poses two major possible dangers to a bird. The biggest one is hypothermia: birds stay warm by trapping tiny pockets of air under their feathers, and if those pockets fill with water instead of air, that bird is going to get cold very quickly. (This is why down jackets don’t work when wet.)

Do birds like being wet?

Birds like to get wet. Water makes them feel good and it stimulates normal preening behavior. You can dampen your bird by using a spray bottle set to “mist” not “spray.” If your birds don’t like being misted directly, spray up so the water falls like rain.

Do birds like being sprayed with water?

Your bird may enjoy showering with you, sitting on a special perch that sticks to the tile with suction cups at the back of the shower. Direct water pressure from the showerhead may frighten or even hurt your bird, so a perch farther from the direct spray, where the bird can be splashed gently, is generally ideal.