Anyone who is familiar with Blue-gray Gnatcatchers and who bothers to rise in the twilight of dawn, will know that individuals often sound off excitedly at first light, for minutes on end, all from a single perch (in other words, the sound-maker calls like crazy but does not move around).
Is this a type of dawn song? It’s certainly not musical. Rather, it comes across as an excited, measured series of typical mew calls, sometimes given rhythmically in pairs. But is it song? Given that both sexes look alike, plus the fact that you cannot see the singer in the dim twilight, it would be difficult to determine if it’s the male or the female who is calling, but my hunch is that it’s the male and that it is, in fact, a kind of advertising song.
Here is an example that I recorded at dawn today, April 20, next to my camping spot at Land Between the Lakes, Kentucky:
A Blue-gray Gnatcatcher calling (or is it singing?) at dawn. Recorded by Lang Elliott at Land Between the Lakes, Kentucky, April 20, 2010.
The Rest of the Story:
There is another vocal display given by the Blue-gray Gnatcatcher that is much closer to what we humans call “song,” meaning that it is musical in quality and has a timing pattern reminiscent of the songs of other species. It reminds me of the song of a catbird, but it is a higher, more delicate ramble of squeaks and whistles. And sometimes it includes imitations of the sounds of other species. Below is an example I recorded last night, right at dusk. The recording begins with typical calls, followed by about twenty seconds of so-called “complex or musical song” before reverting back to typical calls:
A Blue-gray Gnatcatcher calling at dusk, and then breaking into a sequence of song-like musical phrases. Recorded by Lang Elliott at Land Between the Lakes, Kentucky, April 19, 2010.
I find this so incredibly unusual, this peculiar “singing” behavior of the Blue-gray Gnatcatcher. They don’t do it very often. The males of most species of birds sing quite regularly and predictably. But not the Gnatcatcher. Musical utterances happen very unpredictably (or so it seems), and they don’t last very long. So is this truly “song,” at least in a functional sense (for advertising territory, attracting a mate, and maintaining a pair bond)? Perhaps the mewing at dawn actually functions more like typical song and these musical interludes are something else entirely, having to do with close interactions between mates.
A study by Richard Root in 1969 seems to bear this out (Condor, Vol. 71, No. 1, pp. 16-31). Root documented several instances of males giving their soft musical rambles in the presence of newly arrived females, before showing them potential nest sites. Root also described an entirely different “advertising song,” composed of typical mew calls. So it appears that the male gnatcatcher has two completely different categories of song. One—a rapid series of mew calls—is used for advertising his territory, and another—a series of soft musical phrases—is given primarily during close encounters with females.
Now that’s pretty cool, isn’t it?