Interesting discussion of the well-known phenomenon of cowbird parasitism. My most vivid observation of this came in 2011 at Grandview Cemetery in Fort Collins. On the July17th I watched two parent Ruby-crowned Kinglets delivering food to a striped, full-grown cowbird fledgling. While the obviously pushed-to-the-edge adults were off gathering food for their monstrous foster child, the cowbird youngster flew to the ground and fed rather normally in the grass. When the adults came back, the cowbird flew up to a spruce branch, quivered, fluttered and called loudly. As Chuck described, the parent heads literally disappeared in the gaping red cowbird mouth. The only item being delivered I could identify was a winged Cooley gall adelgid ("woolly aphid"), which at the time were emerging en mass from drying galls on spruce. At least in 2011, it was stated in the BNA account for RcrKinglet that although this species had been observed feeding cowbird nestlings, it was unknown if they could actually pull off the task of getting these nest parasites all the way to the finish line (that is, independent life). I think based on what I saw, they can and apparently some of the others who have responded here concur.
The other day I posted about Grandview Cemetery's current hummingbird activity. The Broad-tailed Hummingbird nest in Douglas-fir near the entry bridge hosting the female I am all but certain was also carrying thistle fluff to a second nest under construction was empty today. I saw two young nestlings being fed as late at last Saturday (June25). Something either took the babies, or, just as likely, a strong wind blew this nest, positioned precariously on the side of a nearly vertical branch, to the point of dumping the young. Since the nest looked to be in tact, maybe it really was the wind.
North of Fort Collins on Larimer CR5, our Boulder County Nature Association class field trip on 6/26 witnessed the activities of two families of recently-fledged Loggerhead Shrikes. One of the class members, Sandra Larsen, found a freshly-impaled female Lark Bunting head on the fence in the middle of one shrike territory.
As yellow warblers know, breeding season is full of perils.
Dave Leatherman
Fort Collins
The other day I posted about Grandview Cemetery's current hummingbird activity. The Broad-tailed Hummingbird nest in Douglas-fir near the entry bridge hosting the female I am all but certain was also carrying thistle fluff to a second nest under construction was empty today. I saw two young nestlings being fed as late at last Saturday (June25). Something either took the babies, or, just as likely, a strong wind blew this nest, positioned precariously on the side of a nearly vertical branch, to the point of dumping the young. Since the nest looked to be in tact, maybe it really was the wind.
North of Fort Collins on Larimer CR5, our Boulder County Nature Association class field trip on 6/26 witnessed the activities of two families of recently-fledged Loggerhead Shrikes. One of the class members, Sandra Larsen, found a freshly-impaled female Lark Bunting head on the fence in the middle of one shrike territory.
As yellow warblers know, breeding season is full of perils.
Dave Leatherman
Fort Collins
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