A Song for May 30

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Click the sonogram to hear and see the sound.

Let me set the stage. I began studying the vocal repertoires of certain flycatchers in 2003. First it was Empidonax, a hard-to-identify group that everyone knows by their scientific name. Then it was their close relatives, the phoebes (Sayornis). That led me to get serious about species south of the United States, because the Black Phoebe (S. nigricans) sings differently in South America and the United States. That suggests that the two continents might harbor different species of Black Phoebe. But, there were no recordings from Central America to clarify the situation. The range of the Black Phoebe is continuous from Bolivia to Oregon, so where is the break, if any exists? Then Jesse Fagan got a great recording of dawn song from Costa Rica, but more was needed.

Guatemala was the obvious place to look. Why? Becuase Guatemala and Costa Rica, although close together geographically, are separate centers of endemism. The Yellowish Flycatcher, for example, has different subspecies in the two countries. The phoebes also could have distinct populations in the two places. If there are two species, the lowlands between Costa Rica and Guatemala could be the boundary. And, there was another enticement besides the phoebes, the Pine Flycatcher ( Empidonax affinis). Steve Howell had written in his field guide to Mexican birds that the Pine Flycatchers sang differently east and west of the Isthmus of Tehuantepec. He had recorded dawnsong in the western population, but no recording existed for the eastern population, which resides in Chiapas and Guatemala. So, Pine Flycatcher and Black Phoebe were my primary targets for a trip to Guatemala. The Wilson Ornithological Society gave me a grant to defray expenses and I was off.

I was there, and I had scored with the phoebe at Los Tarrales, but it was too low for the flycatcher. My host there had heard that Corazon del Bosque had Pine Flycatchers, so I transferred to this eco-lodge in pine-oak woodland, north of famed Lake Atitlan. A full day of scouting had turned up a nest of the local subspecies of Yellowish Flycatcher, new to me, but no Pine Flycatchers. Nonetheless, I went out at dawn hoping to find one. I knew what they sounded like west of the Isthmus, but not here. I found this, the most amazingly energetic and complex flycatcher sound I have ever heard. I knew from the syntax that it had to be a flycatcher. I never saw it, as it moved about in the low oak canopy above me. I must admit that I hoped ardently it was the Pine, or rather, a hitherto unrecognized species of Empidonax that looked just like Pine but was not it.

That was the 30th of May. A whole day in the area traversed by the mystery singer did not turn up a Pine Flycatcher, but several Tufted Flycatchers were in the area. I was back out at dawn the next morning. The same song was in the same place, but nowhere else. After dawn, Tufted Flycatchers were the only suspects in the area. I should mention here that many kinds of flycatchers use entirely different songs before and after dawn. The dawnsongs are more complex, the most complex vocalizations they have. So, it was not too surprising when I circulated my recording to several experts on Central American birds and no one recognized it. Meanwhile, Knut Eisermann shared recordings of Guatemalan Pine Flycatchers that clearly eliminated that species from consideration. During daytime, a Tufted Flycatcher was present and giving known daytime vocalizations exactly where I recorded the mystery song. I concluded that it was made by him. Then, in 2017 I recorded a very similar song in Arizona. Once again, I did not see the singer, because it is really hard to see anything at this time of day, and these particular singers stick to the top of the canopy. But, a Tufted was present. Nothing else in that well-known area could have made those sounds, and they were similar to the ones from Guatemala. So, now we know the dawnsong of the Tufted Flycatcher. It has become my new research focus, and if Covid-19 hadn't come along I might have already finsihed a webpage on the differences among vocal repertoires of the four subspecies of this, the most attractive little flycatcher on the planet.

I got interested in flycatcher vocalizations from a birding perspective, but they, the birds and their sounds, have repaid my interest with much, much more. Their songs and singing are unique in the bird world, not learned, but more complex, syntactically, than all other innate vocalizations, and many of the learned ones as well. And this system for assembling a song, which you see exemplified above, this Tufted Flycatcher whose song I found accidentally, it is the most complex I have yet encountered. I haven't looked at the South American flycatchers yet; who knows what wonders lie hidden among them?

Below is a static sonogram with each note labeled. In setting up the reperoire of notes, I started with A, M, and W, which are used independently as calls. P is clearly distinct. B and C may be variants of the same note type, but certainly they represent at least one note type. N, however, may be a variant of M. (I think I misclassified the second A in the fourth song; it should be an N.) Whether there are five note-types or seven, they provide more combinatorial possibilites than I have seen in the other flycatchers I have studied to date. But there is more. I see pauses after each W and P, so I would call clusters of notes ending with W or P a song. This patterns is consistent throughout several minutes of tape from this bird and from a bird in Arizona. Questions abound. For example, can you predict from the introduction whether you will get an M or W at the end of each song. How rigid is the alternation of M and W? Do the different subspecies have different rules? And so on. It's great fun.

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