The last two summers, my visits to Grandview Cemetery in Fort Collins (west
terminus of Mountain Avenue, Larimer County) have focused on Broad-tailed
Hummingbird nests. In summer 2013 I knew of 5 nests. The earliest fledging
from any of these was June 15. The latest fledging was August 15. William
Calder's BNA account states that at high elevation, such as Gothic where much
of his research was conducted, only one nesting cycle is possible. He also
mentions that 2 cycles have been suspected of being at least possible at lower
elevation, with the best evidence coming from Alfred M. Bailey in 1974 in
Denver. Dr. Bailey, renowned associate of the Denver Museum of Natural History
(now Denver Museum of Nature & Science), observed a female feeding 15-day-old
young while also incubating eggs in another nest 2 meters away. Fueled by Dr.
Bailey's anecdote, a nesting cycle from nest construction thru fledging that
takes about only 6 weeks, and last summer's first and last fledging times at
Grandview being separated by 8 weeks, I really wanted to try and document two
breeding cycles this year.
So far in 2014 at GC there have been 4 nests with active young: the 5-year
"champion" Colorado blue spruce nest I've mentioned in previous posts, a nest
re-used for the 2nd year in a juniper, and 2 other first-time spruce nests. My
belief is that three of the four successfully fledged two young each. Of
these, the last young fledged today around 1pm. While the fledging event was
not directly witnessed (drat), I know it happened about that time because I
photographed the two nestlings on the nest as late as 12:30pm, ate lunch on a
bench nearby, tried to show John Shenot the nestlings about 1:30 and they had
flown from the nest. At least one youngster was heard (the recent fledglings
make a note that sounds very warbler-like) high in the nest spruce, and was
apparently being tended by the female.
John and I walked around a bit in another area of the cemetery. Just as we
were parting ways, a female came to a low spruce branch near us and added a big
wad of "fluff" to a half-built nest I didn't know about. That makes 5 nests,
and the timing of this construction immediately following fledging from the
other 4 certainly raises the question whether this is a female initiating a
second cycle. Without banding these females, proof of two broods is
impossible, but I strongly suspect it is happening.
Dave Leatherman
Fort Collins
--
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/SNT148-W60CE1C9542ABFF50192D45C1050%40phx.gbl.
For more options, visit https://groups.google.com/d/optout.
