All, I've been doing crossbill fieldwork for a little over a week on the Grand Mesa and thought I'd share a few notes.
While many birds are well into migration or wandering around the forest in post-breeding, mixed foraging flocks, Red Crossbills are taking advantage of a huge spruce cone crop and a new breeding season is underway. The vast majority of birds have either just completed nest construction and are in the process of egg laying/incubation or are currently building nests. What's really interesting is that a high proportion of breeders are immature birds that were born in late winter/early spring this year. It seems that there is a high degree of age-based assortative mating, where immature birds are paired up among themselves as are adults. It also seems that adult birds tend to be further along in breeding than are immature birds. The most exciting part for me is that types 2 and 5 (the former being a bit more abundant than the latter, interestingly) are both breeding synchronously in the same habitat, even nesting in adjacent trees in some cases -- certainly a much different scenario than years when only ponderosa and lodgepole are producing cones. I've also had a handful of type 4 around, possibly in breeding pairs, though it's hard to say at this point. Still waiting for White-wingeds to show up... In other news, warbler migration has really picked up in the past few days, with large mixed flocks of Wilson's, Townsend's, MacGillivray's, and Yellow-rumpeds bopping around, often times joined by the large chickadee-kinglet (both species) flocks that also seem content to do their own thing. I've also been a bit surprised at the numbers of raptors (Swainson's, Red-taileds, and Cooper's) hanging around the high elevation meadows. Montane goodies like Pine Grosbeak (many), Gray Jay (many), Evening Grosbeak, American Three-toed Woodpecker, and Dusky Grouse have also kept things interesting. My first Colorado Pine Marten was also a delightful surprise. On the north slope of the mesa there is a large acorn crop, though I've only seen a single Woodhouse's Scrub-Jay so far (possibly due to a lack of effort). Good birding, -Cody Porter (Laramie, WY; currently alternating between Grand Mesa and NE Utah) -- 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/a220d9ce-ad78-4931-b8d3-f7d90fbd33dc%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
