{"id":3953,"date":"2012-09-18T22:19:38","date_gmt":"2012-09-19T04:19:38","guid":{"rendered":"http:\/\/earbirding.com\/blog\/?p=3953"},"modified":"2012-09-18T22:21:05","modified_gmt":"2012-09-19T04:21:05","slug":"the-two-part-calls-of-empidonax","status":"publish","type":"post","link":"http:\/\/earbirding.com\/blog\/archives\/3953","title":{"rendered":"The “Two-part Calls” of Empidonax"},"content":{"rendered":"
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If only it would sing! Probable Hammond's Flycatcher, Wyoming, 6\/17\/2010. Photo by Bryant Olsen (CC-by-nc-2.0)<\/figcaption><\/figure>\n

Empidonax<\/em> flycatchers are tough to identify by sight.\u00a0 Every birder knows it.\u00a0 They’re the classic bugaboo of North American bird identification.\u00a0 That’s why every field guide mentions the importance of listening to their voices.<\/p>\n

But Empids make a lot of sounds.\u00a0 Forget about learning “the<\/em> song” and “the<\/em> call.”\u00a0 Most Empids have repertoires of 6-8 different songs and calls. Some species, such as Pacific-slope and Cordilleran, have a dawn song<\/a> that’s different from anything they say during the day.\u00a0 Several, including Least, Yellow-bellied, Hammond’s, and Dusky, have complex, rarely-heard flight songs. The species with the largest vocabulary appears to be Acadian Flycatcher, which has all of the above types of song plus another type, sometimes called the “evening song<\/a>,” which is the most complex of all.\u00a0 (It may or may not be fully separate from the flight song.)<\/p>\n

Today I’m going to be talking about a class of Empid vocalizations that don’t get much press. I’ll call them “Two-part Calls” since they don’t have an official name.\u00a0 Based on their similarity, the “two-part calls” appear to be homologous — that is, evolutionarily equivalent, all descended from the same calling behavior of a common ancestor.<\/p>\n

As far as I know, three species of Empids give these calls. In one species, the two-part call is familiar enough to be mentioned in field guides, at least. The two-part call of the second species is described only in the scientific literature.\u00a0 And that of the third is, as far as I know, being described in this blog post for the first time.<\/p>\n

Dusky Flycatcher: “Du-hic”<\/h4>\n

This call is mentioned in the Sibley Guide to Birds<\/em>, Kenn Kaufmann’s Advanced Birding<\/em>, and other well-researched field guides.\u00a0 The “du” part of the call is nearly monotone, and the “hic” is shorter and slightly higher.\u00a0 As you can hear in the following examples, the sequence is often more like “du, du, du, du, du-hic”.\u00a0 Sometimes the “hic” notes will be given without a “du,” or after other “hics.”<\/p>\n\n\n\n
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