Hi, all. Thanks to Matt Hafner for these great observations from Florida. > Has anyone else heard a large predawn flight with such a lack > of diversity? Most of my listening has been inland in the mid-Atlantic > and while I've had plenty of thrush-dominated mornings, I've never > had a single species compose so much of the calls. Gimme a few months, please, and I'll be able to post a quantitative summary for July-November for Boulder County, Colorado, 2007-2009. In late July and early August, when we have decent flights (30+ flight calls per hour), they are dominated by Chipping Sparrows. I'd say 80-100% of the flight calls are given by Chipping Sparrows on those nights with decent flights; by mid-August, diversity increases. These lateJuly/earlyAugust flights are full-on, sustained, middle-of-the-night flights of birds on active nocturnal migration. (Cf. ongoing discussion about the definition of night; and "old-timers" may recall that we discussed zugunruhe vis-a-vis actual nocturnal migration, way back in the old days of August 2009!) Here's something to ponder. I'm certain that warbler/sparrow calls are going to be more than 90% of all flight calls, in the final analysis here in Colorado. Probably more than 95% of all flight calls. The total number of thrush calls is going to be less than 1%, and perhaps down around 0.1%. In contrast, y'all Back East have experiences like this: thousands of thrushes; a decent smattering of grosbeaks, tanagers, and Bobolinks; and 1 or 2 sparrow notes. (There have been several such postings to NFC-L in the past month; seriously, *one or two* sparrow/warbler flight calls amid literally thousands of flight calls of larger species.) Here in Colorado, again, the warbler/sparrow notes are dominant, overwhelmingly so. I've been out most nights the past 2 weeks, and I've heard absolutely nothing but warblers and sparrows. The IDs are provisional, but most seem to be Orange-crowned and Yellow-rumped Warblers, plus Chipping, White-crowned, and Lincoln's Sparrows. Mainly presumed Yellow-rumps and White-crowns. Believe me, if I heard a thrush or Bobolink, or just a wimpy Western Tanager, I'd jump out of my pants. Best, Ted Ted Floyd tfl...@aba.org Lafayette, Boulder County, Colorado P.s. I'm talking about fall in Colorado. In spring, we get Swainson's Thrushes, Bobolinks, grosbeaks, buntings, all that good stuff.
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