Wednesday, 15 February 2017

[cobirds] Bushtit nesting in Fort Collins

Yesterday, sitting at the computer with my Fort Collins apartment door wide open, I noticed the familiar tinkling sound of bushtits in the courtyard.  Last year they nested on this property (nest building first noticed on 12March2016) about a mile east of CSU and it appears they will do so again.  In fact, they are refurbishing the same nest which successfully produced a brood last summer.  In the "Birds of North America" account on bushtits by Sarah Sloane, it states the following: "In Chiricahua Mtns., se. Arizona, on only 1 occasion was a nest reused a second season, and this was late in season by a year-old inexperienced male; nest had remained unusually intact through 2 winters due to heavy concealment in a clump of mistletoe (SAS). Most nests deteriorate rapidly when abandoned."  The nest here is at the end of a lower branch (about 20 feet above the ground) on the ene side (catches the morning sun) of a large CO blue spruce.  As is typical of the species, the substantial nest "bag" is well concealed and woven into the spruce foliage.  Even knowing where it is and looking straight up at the nest site, it takes me a minute or so to locate the nest material hiding in the needles.


I would also note Coen Dexter mentions in his bushtit account for the Colorado Breeding Bird Atlas II book that the earliest recorded nest-building was 17March.  Thus, nest-refurbishing on 14February is either a freak event triggered by hormonal influence on Valentine's Day, preliminary activity influenced by both warm weather and the existence of a suitable old structure, an indicator things are changing, or most likely, just the early end of activity that birders, especially BBA atlasers accustomed to doing most of their work in "typical" bird breeding months, have missed.


Anybody else noticing bushtit nesting activity out there?


Dave Leatherman

Fort Collins

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