Hi all: I write just to provide more information on the topic and to point out one important aspect of Breeding Bird Atlases that many do not consider. Breeding Bird Atlases (BBA), like ALL bird-data sampling schemes, is biased. "How," you might ask. Well, they are designed to get the most bang for the buck, because bucks in bird-sampling schemes are virtually always hard to find in sufficient abundance to do what one really wants to do. In the case of BBAs, field work is usually (nearly always) focused on the season when most locally breeding species are nesting. That means that species that nest outside of the typical, perhaps, April-August time period, get short shrift. Red Crossbill is one such species. (Others include most owl species -- early; most hawk sp. -- early; Clark's Nutcracker and Pinyon Jay -- early; and American Goldfinch -- late. There are quite a few others.) Though Red Crossbill can be found breeding at any time of year if there is an abundance of food (conifer seeds), the species is primarily a winter breeder. One can see this in the Second Colorado BBA if one looks at the data graphs with an eye to detail. While nest building was recorded for RECR in the 2COBBA from mid-March into September, note that fledged young were noted from late February through mid-October. Obviously, to have fledged young in late February, one would need to begin nesting efforts before March. FUN FACT: Red Crossbill is even known to breed in juvenile plumage if the seed abundance that supported its production stays high enough to support such. I recall someone running into the same sort of misinformation in the First Colorado BBA, noting that Loggerhead Shrikes began nesting in June. Of course, June is only when most atlasers get out there to record nesting birds; the shrikes actually begin nesting in April, which is why they often have fledged young in late May and early June, even though there were no atlas records of nest building before June. For the Red Crossbill, just imagine trying to go out in January in the deep snow in the mountains to search for their nests. Yeah, I won't do it, either, though I have seen a crossbill on a nest (on the Grand Mesa) in January -- fortunately, right next to the paved road. Unfortunately, those of us that saw it could not see it well enough to determine which species of crossbill. Bummer! Here in se CO, while the wind stayed southerly, cloud cover increased and the wind speed picked up, making for less-than-stellar hawk-migration conditions. I assume such conditions hit the Front Range earlier in the day, which might have put the kaibosh on any hawk flight. Or not. I'll be curious to see today's results.
Sincerely, Tony Tony LeukeringWiley, CO -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/cobirds/1937571640.9128156.1553221001233%40mail.yahoo.com. For more options, visit https://groups.google.com/d/optout.
