I was having trouble accessing my Birds of North American (BNA) account this
morning when I first posted about swallows. Apparently the reference I quoted
in lieu of BNA (Erlich's Birder's Handbook) about Cliff Swallows sometimes
having "2-3 broods per year" is in error. The Birds of North America account
by Brown, which is heavily based on studies of this species in Nebraska, states
Cliff Swallow is single brooded. Evidence of late summer nesting is usually
the result of nest failures earlier in the summer. This is also stated in the
BBA I account authored by David Pantle (which heavily references Bailey and
Niedrach's Birds of Colorado). Thus, part of my question was answered once I
straightened myself out on this brood business. Barn Swallow is the only
regularly double-brooded swallow species in CO. Apparently Bank Swallow is the
only other swallow species that is sometimes double-brooded in N.A. but that
usually (always?) occurs in areas outside CO. It stands to reason, then, that
in our state Barn Swallows would require a longer summer stay to accomplish
their breeding tasks.
I appreciate the comments about the post, most of them observations of Barn
Swallows and Cliff Swallows seen of late. The more I think about this, the
more questions come to mind. It still seems like Barn Swallows are the lone
representatives of the swallow clan for a longer period of time at the end of
the breeding season than they used to be (that is, either they are staying
longer and/or the other 5 species are leaving earlier). Why is a seemingly
semi-hardy species like Tree Swallow (which often is the first to show up in
spring) among the set of swallows that leaves toward the end of July-early
August? Why do most of the swallows leave rather abruptly after their broods
fledge, when the majority of other passerine species stick around until times
get tough?
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-W53307ADC0ADAB0C1E2567AC1290%40phx.gbl.
For more options, visit https://groups.google.com/groups/opt_out.
