Hello, Birders. Walter M Szeliga, [email protected], writes: > Typical mountain species were abundant including > MacGillivray's Warbler (or Mourning, you'd have to read > Ted's ID Frontiers post), Audubon's Warbler, Green- > tailed Towhee, Broad-tailed Hummingbird, &c. In case you're scratching your head, here's what Walter was talking about: http://tinyurl.com/28fyvm9 Bottom line: Birds that look like good Mourning Warblers may well be MacGillivray's x Mourning Warbler hybrids. What we see in the field isn't necessarily what the bird really is. Check out the photo on the bottom right of p. 30 (from the link above). If you saw that bird in Colorado, would you put it on your list as a Mourning Warbler? Of course, you're welcome to! You could call it a Connecticut Warbler, for all I care. But that wouldn't make it a Connecticut Warbler--or a Mourning Warbler, either, for that matter. Every week, it seems, there's a major research article documenting yet another instance of cryptic hybridization in birds--and we in Colorado are at the North American epicenter of the phenomenon. So many of our birds just can't be fit into a box. Here's a short list of Colorado bird "species" that sometimes--perhaps oftentimes--cannot be safely identified in the field, because of the problem of hybridization * Ross's and Snow geese--Snow Goose is paraphyletic with Ross's Goose, and Ross's x Snow hybrids may be common
* American Black Duck--because many, perhaps most, individuals at the western range limit show introgression with Mallard * Glossy and White-faced ibises--because we don't know how to distinguish "pure" variants from backcrossed hybrids * Glaucous-winged Gull--because many individuals, most in some regions, are hybrids with Western, Herring, or Glaucous gulls * Kelp Gull--U.S. breeders in the 1990s hybridized extensively with invading Herring Gulls * Barred Owl--where invading Barred Owls come into contact with Spotted Owls, hybridization is rampant * Black and Eastern phoebes--as Nathan Pieplow has shown, secondary contact in Colorado is resulting in hybridization * Blue-headed and Cassin's vireos--species limits with Plumbeous are highly "fuzzy" * Blue-winged and Golden-winged warblers--the classic example of cryptic hybrids; pure-looking birds are frequently hybrids * Tropica Parula--most birds in south Texas are known or presumed hybrids with Northern Parula * Hermit Warbler--hybridizes extensively with Townsend's Warbler; backcrosses impossible to distinguish from Townsend's * Mourning Warbler--see above * Eastern Towhee--hybridizes with Spotted Towhee, an exceedingly variable taxon (itself perhaps comprising multiple species) * Black-headed and Rose-breasted grosbeaks--hybrids are common * Lazuli and Indigo buntings--hybrids are common * Blue Grosbeak--apparently hybridizes with Indigo Bunting * Bullock's and Baltimore orioles--hybrids are common * Black, Brown-capped, and Gray-crowned rosy-finches--species limits are poorly known, and hybrids may be common That's just a short list, off the top of my head, involving well over 25 "species" in Colorado. What does it "mean" for us birders? Well, it means birds are amazingly variable, incredibly cool, and endlessly fascinating. It means I want to get out in the field, more so than ever, and check out all the intriguing biology that's going on out there. It reaffirms something I've felt for the 8+ years I've lived and birded in Colorado: Our state is one of the absolute coolest places on earth for birding. And it reminds me, one more time, of the folly of trying to put birds in a box. Birds are too variable, and way too cool, for that. ------------------------------- Ted Floyd Editor, Birding Follow Birding magazine on Twitter: http://twitter.com/BirdingMagazine ------------------------------- _________________________________________________________________ Hotmail is redefining busy with tools for the New Busy. Get more from your inbox. http://www.windowslive.com/campaign/thenewbusy?ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_2 -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/cobirds?hl=en.
