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Flycatchers for every niche

Can there ever be enough flycatchers? Certainly not in mosquito season.

We have flycatchers for every habitat. There are flycatchers in the grasslands (western kingbird), in the oaks (western wood pewees), in the deep forest (Hammond’s flycatcher), at timberline (olive-sided flycatcher). We even have one that stays though the winter, the black phoebe.

Now if you are trying to identify the different flycatchers, maybe we do have too many. Some birders think so. There are  many to learn, and many look virtually identical. The worst are the “Empidonaxes,” often dismissed as “LGB's" (little green birds). “Empidonax” is part of the scientific name of this group of flycatchers. We have seven of these almost impossible to identify species in Oregon.

Flycatchers, at least ours, all look sort of the same. They have large heads often with a short bushy crest. They have a short bill and short neck and tend to perch upright. Most are “sit-and-wait” predators. They wait patiently for some passing insect, and then sally out to pluck it out of the air, often returning to the same perch to wait for the next victim.

There are 34 species of tyrant flycatchers across the United States and Canada. That’s a lot more than we have of thrushes (14) or chickadees and titmice (12). If you think 34 species of flycatchers is a lot of flycatchers, try Costa Rica (70 species) or, better yet, Argentina (142 species). They have so many species in South America that it stretches the imagination to come up with names for them all. They have resorted to names like bran-colored flycatcher, marble-faced bristle-tyrant, brownish twistwing, and drab water tyrant.

And the flycatchers in South America don’t all look similar. Some are the size of kinglets and behave like them (tufted tit-tyrant). There are those with long legs that stomp around on the ground like Brewer’s blackbirds (cattle tyrant), and those inhabiting marshes that fill the ecological role of our marsh wren (many-colored rush tyrant). The large shrike-tyrants have turned mean and hunt lizards and small birds like our shrikes. Then there are those with bizarre and over-sized tails like the strange-tailed tyrant. What is going on in South America? Why have the flycatchers all gone crazy?

If you think back to your sixth-grade science classes, you probably remember something about plate tectonics. Pieces of the Earth’s crust, some carrying the continents, are playing a giant game of bumper cars. South America spent a lot of time floating around in the oceans all by itself until recently (geologically speaking) when it finally ran into North America. During all that time alone, they had no warblers, vireos, chickadees, kinglets, wrens or many of the other species of insect-eating birds common to us. But they did have tyrant flycatchers. In the absence of warblers and such, flycatchers diversified to fill a great many of the vacant niches resulting in the bewildering array of flycatchers that we see today.

Spring is coming, and it’s time to brush up on the finer points of flycatcher identification, especially the LGBs. When you get frustrated with the diversity of flycatchers in Oregon, just remember, it could be a lot worse.

Stewart Janes is a biology professor at Southern Oregon University. He can be reached at janes@sou.edu.

Courtesy audubon.org