Thursday, January 20, 2011

Follow the Titmouse Down the Prairie Dog Hole: What Bird Sounds Mean

[Tufted Titmouse in a short flight to a new patch of trees along Delaware Bay.]

srEErEE....srEErEE...srEErEE...

That's what I heard as I stepped from my truck, parked near the Cape May National Wildlife Refuge Songbird Trail on Kimble's Beach Road. Rapidly slurred, very high pitched and squeaky.

I recognized a Tufted Titmouse's voice in the sounds, indeed have heard them give this vocalization often, though it seems not to be described in any of the standard field guides. No big deal - if you hear a bird in woodlands and don't know what it is, it's a Tufted Titmouse, right? If you go to this page and scroll down, you can listen to the sound, or one like it, and see a spectrogram - it's the high-pitched recording for Tufted Titmouse made in March in PA.

It turns out that several different pairs, or small groups, of titmice were making this call at the Songbird Trail today as (because?) I arrived. I found one pair, perched near each other, repeatedly vocalizing. "Why are you doing that?" I asked. They did not answer. No worries, I thought, BNA Online will know.

Well, BNA online didn't know, in fact didn't even mention this vocalization. SORA (Searchable Ornithological Research Archive) didn't know, or I couldn't find an article about it. I don't have my copy of Donald Kroodsma's The Singing Life of Birds at hand, but that's the next place to check.

So, in the meantime, on to what in some senses is still the court of last resort on bird behavior: Arthur Cleveland Bent's Life Histories of North American Birds.  Haven't been there in a while, where  we can read about the titmouse in the 1946 Life Histories of North American Jays, Crows and Titmice: ". . .He presents many claims to the rank of first nobleman of the forest realm. His presence is genial and pleasing, his plumage attractive, his alertness conspicuous, and his habits are good." Now that's what I call nature study!

Even Bent has nothing about this srEErEE business, though he says, "The notes of the Tufted Titmouse are many and varied, mostly loud and generally pleasing; it is a noisy bird."

Along about now folks might be wondering, what does all this have to do with prairie dogs? More than you'd think. This morning I tuned in to NPR to find an astonishing story on Prairiedogese - if that link doesn't work, go to http://www.npr.org/ and search the site for "Radiolab Prairiedogese."

The story is based on the work of Professor Con Slobodchikoff of Northern Arizona University . The professor studies Gunnison's Prairie Dog (Cynomys gunnisoni; if you're a mammal nut like me you want to know which prairie dog we're talking about.) The radio show plays different sets of prairie dog vocalizations, which to the NPR announcer and most normal people all sound alike, but to a serious ear birder the sounds are quite different, something easily revealed in a spectrogram. It turns out the prairie dogs use different vocalizations to warn of different predators, but it goes farther than that. The prairie dogs DESCRIBE the predators, e.g. they use different vocalizations for approaching humans if they are tall or short, or wearing red or blue shirts!!!

Now back to Bent and the titmouse: "Dr. Dickey tells me that they are 'seen to react to the voices and noises made by road workers, drillers and farmers. They hurry forward from shelter in twos or threes. Even when a visitor calls at the door of a house and starts to talk, then the titmouse arrives, evidently curious at a stranger in its habitat. I sometimes hesitate to wonder if such birds do not discriminate between the natives and strangers, for they have a sagacity that is hard to fathom.'"

Just what were those titmice saying when I arrived at the Songbird Trail this morning? Courtship? Alarm? Conversation?