Hello, Birders. Thanks to Bryan Guarente for this intriguing report. As Bryan wisely notes, "[F]eel free to question me on this. It could be a good learning experience for all involved."
Well, as if to corroborate Bryan's report, a Swainson's Hawk was reported migrating over eastern Prowers County on Friday, Feb. 24th. The bird was seen by multiple participants on a field trip with the High Plains Snow Goose Festival. Note: I was NOT on that field trip. However, one of the folks I talked to sure seemed to know what she was talking about, and, in particular, she was well aware of the unusual date for Swainson's Hawk. Two points of context: First, a year or so ago, there was a published report (based on eBird data) on increasingly early return-dates for spring Swainson's Hawks in the United States. Something to keep in mind. Second, BRYAN, can you comment on the weather? In Prowers County, we had moderate south winds this past Fri.-Sat. Could that have been a factor? Good stuff! Ted Floyd [email protected] Lafayette, Boulder County, Colorado Subject: EARLY Swainson's Hawks: Boulder/Weld Counties From: Bryan Guarente <dafekt1ve AT yahoo.com> Date: Sat, 25 Feb 2012 15:59:44 -0800 (PST) CoBirders, While out traveling the windy roads of Boulder county today, my wife and I were at the intersection of Highway 52 and County Line road heading west (into the wind). I asked my wife while we were still in Weld County if she could identify the raptors (2) flying over the intersection for me since I was driving. She looked for a second and didn't respond... this was intriguing enough because usually she is very good with her raptors and an answer comes quickly. I slowed a little while going through the intersection crossing into Boulder county. Both birds were heading north-northwest and turned east momentarily to show the characteristic black (or nearly black) primaries, secondaries, and tertials on the underside but off-white (or whitish) coverts. When they banked again the other direction, I saw one of them had no other color on the upper part of the wing aside from dark brown (on the primaries, secondaries, and tertials) and a slightly lighter brown on the coverts. Neither my wife nor I got good looks at the tails, but without that data, I am still pretty certain that these birds were Swainson's Hawks (I didn't truly rule out Short-tailed Hawk or White-tailed Hawk in the field because I have no experience with either). I believe based on the lack of any other colors on the upper wing that this bird could not be a White-tailed Hawk. I also believe that the "bi-colored" upper wing rules out Short-tailed Hawk upon inspection of books upon arrival home. Likely both the White-tailed and Short-tailed Hawk can also be ruled out by the color of the underwing coverts (off-white, not pure white). Lastly, and likely least important because of the extreme earliness of the record, Swainson's Hawk is the most likely species in Colorado in general. Osprey was ruled out based on wing length being shorter on the birds in question. Red-shouldered and Broad-winged don't show nearly as dark or solidly colored primaries, secondaries, and tertials on the underwing. I know there will be people out there who won't believe me, and feel free to question me on this. It could be a good learning experience for all involved. Bryan Guarente Instructional Designer The COMET Program University Corporation for Atmospheric Research Boulder, CO -- 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.
