Hi, Tweets. Another two cents' observations about swifts.

I agree with Bryan Gates: I have never heard of black swifts using hollow
structures such as chimneys for roosting or nesting - nor white-throats.
(Thanks, Bryan, for posing the hypothetical, structural explanation.)

>Which brings up my next questions: Does this species tend to return to the
>same chimney(s) in successive seasons?

I suspect the answer is yes, based on site fidelity demonstrated by other
bird species, as well as a presumed limit to the number of appropriate
sites. Though I'm not sure of the exact chimneys, there are one or two
locations in Corvallis, Oregon, where Vaux's put on spectacular displays
every summer, swirling down by the hundreds at dusk. One of the spots is on
the OSU campus. Perhaps some Oregon Tweeters can provide details.

During a brief spell of home ownership in Corvallis, we had Vaux's swifts
nesting in our chimney. We could hear soft twitters and scratching sounds
on occasion. Fortunately we kept the damper closed because one day a baby
fell out of the nest. Since I read somewhere that they can claw their way
back up to the nest in such cases, we left the bird alone and the damper
closed, and it did indeed sound like it climbed back up successfully. We
were trying to sell the house at the time, and my sympathetic but
non-birding husband wanted the chimney free of birds for any potential new
owners. Accordingly, I climbed up to the roof with a flashlight to inspect
the nest. Several fledglings stared back up at me; it was amazing how they
all managed to hang onto that slim shelf. They were just about fully
feathered. Later, when the family started doing the
swirl-around-and-dive-in routine at dusk, it was time to evict them. It
seemed like they had invited some friends to share their roost, 'cuz there
were two or three times the number of birds diving in than there had been
in the original family. I put a net produce bag over the top of the
chimney, felt really guilty, and fervently hoped the birds would switch to
roosting in one of the neighbors' chimneys.

>How do the birds tell a "safe" chimney
>from one that could get hot and smokey at any time?

I suspect they don't. During their breeding season most people don't have
fires in their fireplaces, and the birds have migrated before it gets cold
enough to build them, so they're lucky. Also, if they are successful at
nesting in a chimney not used regularly for burning trash (or whatever), I
would suppose that would lead them to choose the same one again the next
breeding season. In forests, of course, there's slight chance that anyone
will build a fire underneath a hollow old cedar or rotten fir, so I doubt
that potential fires are hard-wired (hot-wired? :) into their brains'
concept of a suitable nest location.

-- Janet Hardin
Port Townsend, WA
wings at olympus.net