Hello, Tweeters,

Sara Blake, a life-long Sequim resident, had always wanted bluebirds
nesting in her yard on the east side of Sequim. She had three nest
boxes in place for 17 years but only swallows nested in them, until
this year...

In February, 2008, a male Western Bluebird showed up. Sara was so
excited she put out some mealworms from the pet store to entice the
bluebird to stick around. Soon thereafter a female showed up, and
Sara continued the mealworms for her as well. Only one other
bluebird ever appeared this year, a male early in the spring, but the
resident male quickly chased him off and Sara never saw more than one
male and one female after that time. Unfortunately the birds weren't
banded, but Sara kept close tabs on them and is convinced there was
only one male and one female in her yard through the rest of the
spring and summer.

Amazingly, with the help of lots of mealworms, these two bluebirds
proceeded to lay four clutches over the next five months, laying 20
total eggs and fledging 19 chicks. Sara says she put out about 1000
mealworms per week, eventually setting the worms in a special guard
by her back door because other birds (Spotted Towhee, WC Sparrow)
also started eating the worms. The male bluebird even kicked at the
back window at times if the mealworm supply ran out. The female
bluebird, being more shy, never kicked the window, but just sneaked
on the porch to pick worms from the bowl, then flew off to feed the
chicks. By the end, Sara had to mail order mealworms from Ohio,
because the local pet stores all ran out supplying her bluebirds.

Sara kept close tabs on the timing of nesting and success: Clutch 1:
4 eggs laid late March, fledged 4 chicks in early May. Clutch 2: 4
eggs laid mid-May, fledged 4 chicks in mid June. Clutch 3: 6 eggs
laid mid June, fledged 5 chicks early August. Clutch 4: 6 eggs laid
late July, fledged 6 chicks early September.

Interestingly, the bluebirds shifted their clutches between three
different closely-spaced nest boxes, which explains the overlap
between the chicks of clutch 3 and the eggs of clutch 4. Sara says
the male continued to feed the big chicks of clutch 3 in one box
while the female moved next door and started the new clutch in
another box. Since the adults easily fed mealworms to the big chicks
in the boxes, there was apparently no need for the chicks to leave
the boxes any earlier than their choosing. Consequently the chicks
stayed longer in the boxes, getting fat and sassy.

In the end, the male bluebird took off before the female, leaving her
to finish feeding the last chicks to fledging in September.

Sara's project turned into a wonderful experiment about the
incredible productivity wild birds could have if food is unlimited.
Imagine all the songbirds there might be if wild caterpillar
populations continued at high levels for months at a time, rather
than spiking in spring for just a few days or weeks. We'd be knee-
deep in warblers! It's also curious that Sara's bluebirds continued
to lay the last clutch well after the summer solstice, suggesting
that in this case food availability was more important than day-
length in determining the timing of the birds' nesting.

Bob Boekelheide
Sequim
bboek at olympus.net





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