The double use of the same nest is interesting. I have been under the impression that most hummer nests fall apart after use - the babies get big and perky and they just bust out of the nest and leave it in shambles. I remember learning from Steve & Deb Bouricius that the fledglings weigh more than the mama by the time they fledge, as she is losing weight all the while she is stuffing calories into them. Steve had observed double broods (broad-tailed and black-chinned) in his orchard on the western slope and had reason to suspect sometimes even a third brood. At the time, he was working on a method for marking individuals with sharpie markers - the birds would peck paint off but seemed to tolerate the markers. Perhaps someone else in this community is more up-to-date on this work than I am.
thanks for sharing this, Dave
- Sandra Laursen
On Sunday, July 23, 2017 at 6:33:38 PM UTC-6, Dave Leatherman wrote:
The barrier has been broken. I suppose we have all had a nemesis bird or biological event we wanted badly to see, should have seen by now, and finally we see it. Then we see it often after that. Part of that is the odds evening out, part of it is newfound search image, part of it is the object or event truly becoming more common than it was before. And then there's luck.
Well, on July 7th I was shown proof that Broad-tailed Hummingbirds are double-brooding in Colorado at Grandview Cemetery (a female fed a fledged youngster and then moved over a few feet to a freshly-built nest with eggs (today she was dutifully on the nest which presumably still has eggs or very newly hatched young). A few days later (July 16th) I saw a different adult female sitting on an old nest that had already produced two young earlier this summer. That's apparently double-brooding, likely (but not necessarily) by the same individual female in the same nest in the same summer. Today I saw two more adult females engaged in activities suggestive of still more double-brooding ongoing at Grandview: (1) a female sitting on a previously undetected, pristine nest (interestingly anchored to a live bough under a live roof, which in my experience at Grandview is true for maybe only 1 in 15 nests (vs. dead branch under a live roof), and (2) a female collecting thistle seed for use as nest building material. See photos below, thistle seed gathering at left, live bough nest at right.
Other things of interest during today's visit from 7:15-11am:
*Blue Jay nest about half way up a very large Colorado Blue Spruce (the way the House Finches were acting, I suspect the parent jays were feeding finch eggs or young to their nearly-fledged offspring).
*One adult Chipping Sparrow (this could either be a lingering parent from the one or two pairs that nested at Grandview or a newly wandered bird from the foothills. I should mention I saw one Chipping Sparrow on the western Pawnee Grasslands last Friday (July 21) that was definitely one of those post-breeding-staging-molt-
migrant-get-Ted-excited-at-3AM birds, my first of the summer.
*One Pine Siskin was among cones at the top of a tall spruce. Surprisingly, they did NOT nest at Grandview this summer.
*Heard one singing House Wren, probably a parent from the documented apricot tree nest cavity. Will they try for another round of young?
*Cliff Swallows are apparently fledging, as I saw far more than I have all summer in the Taft/Laporte Avenue intersection where they nested with Barn Swallows in the irrigation ditch tunnel under the road.
*Was shown a House Sparrow nest that was cleaned from a nest box in a yard on Frey Avenue one block east of the cemetery. It was made almost entirely of rusty brown and white chicken feathers (from a nearby coop) stylishly accented with a Blue Jay feather. The landowner Nancy, who participates in the "Habitat Hero" program of National Audubon, will put out the nest somewhere conspicuous in case birds want to recycle the material.
*Robins eating chokecherries, Fox Squirrels chowing down on green bur oak acorns, saw 1st underwing moth (Catocala sp.) of the summer, pelecinid wasp females flying about looking way more ominous than they are.
Dave Leatherman
Fort Collins
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