Saturday, March 28, 2009
Everything's coming up thrushes
I met this chap while out hummingbird banding.
One of the things I like about this project is that it gets me out at the crack of dawn bird watching. Something I never seem to be able to make myself do otherwise.
So you're outside, sitting still and quiet, and if there aren't many hummingbirds coming to the traps, it's great bird watching time.
The bird in the picture is a Swainson's thrush. One of those robiny species that I take for granted and tend not to pay much attention to.
So, I decided to put my raptor bias aside and learn a little bit about these birds.
First off, they are known for their song. Walt Whitman wrote about it, so did Henry Thoreau.
The reason their songs stands out is that thrushes have what's called a syrinx, or a double voice box that allows them to have air moving in and out at the same time. In essence, they can sing two notes at once and harmonize with themselves.
It makes a chimy, unearthly-sounding song. The hermit thrush's call is especially beautiful. You've no doubt heard them in the wood of the west – or the Swainson's or varied. If you hear a coach's whistle in the woods, there's a varied thrush somewhere nearby. In Eastern North America it's the voice of the wood thrush that inspires poets.
Speaking of the wood thrush.
A recent study involving the birds, fitted with geolocator backpacks for the first time, demonstrated that they migrate about three times faster than researchers had guestimated previously.
They fly about 500km each night and spend the day feeding and resting. Who wouldn't?
Another fascinating thrush tidbit is that they harvest pesticides from ants. People have seen these birds rubbing ants over their feathers. It's called anting, naturally. The most reasonable explanation seems to be that use the insect's defensive secretions to ward off pests.
Parasites are costly for any animal, and there are many examples of animals using natural products as pesticides (because going to the drug store is inconvenient, and they are staunch environmentalists).
Thrushes, it seems, take an ant bath.