Pennsylvania Game News - August 2016 - 49

densities occur in Allentown, Erie, Harrisburg, Philadelphia, Wilkes-Barre, and
especially, Pittsburgh's industrial-river
corridors, according to the Second Atlas
of Breeding Birds in Pennsylvania.
Usually, I see them first in spring in
the sky above First Field, seining the air
and scooping up dozens of tiny insects
at a time.
Chimney swifts return year after year
to the same mate and nesting place. In
Pennsylvania, they most often nest in
June.
Both parents break off twigs with their
feet as they fly, then use them to construct
a nest, with the twigs held in place by a
glutinous saliva the birds produce.
Adding eight to 12 twigs a day, it takes
the pair a week to construct on the side
of the chimney a half-moon nest, strong
enough to hold up to six white eggs.
Both parents incubate eggs, and the
incubating parent waits until the foraging
parent returns before leaving.
After an average of 19 days, the eggs
hatch and, again, both parents brood their
naked young and forage for food.
Paul and Georgean Kyle, authors of
Chimney Swifts: America's Mysterious
Birds Above the Fireplace, write that
hatchlings are so active the parent brooding them "appears to be atop a popcorn
popper."
For the first week, parents feed each
nestling by regurgitating a slurry of insect
body parts and saliva into its mouth. Then
they start feeding one nestling at a time
with a soft mass of chewed food containing dozens of insects.
While only one breeding pair will
occupy a single chimney, unmated birds
also might roost there, and parents allow
other chimney swifts to assist them at
AUGUST 2016	

the nest. Usually they are the previous
year's offspring and, more often, males
than females.
These helpers roost with the family at
night and might even help incubate the
eggs and brood the nestlings.
Many chimney swifts will not breed
every year.
Chimney swifts are intensely sociable,
feeding together, skimming lakes and
rivers for water together, and even flying
over each other's nest chimney and looking inside.
The Kyles have seen the brooding parent move aside as if to show off hatchlings
to those stalling over their chimney.
At 19 days, the nestlings begin perching on the wall beside their nest and
practicing flying.
When they are 28 days old, they fly
out of the chimney, although they return
to roost with their parents and siblings for
one to two weeks.
As soon as they fledge, they feed
themselves the gnats, mosquitoes, flies,
winged ants, termites and other airborne
insects they find.
In Pennsylvania, migrant chimney
swifts begin appearing by mid-August,
and in early September, they form large
communal roosts.
Alert observers near such roosts can
watch in the evening as swifts - sometimes numbering in the thousands - swirl
around the entrance of a commercial
chimney before suddenly flying down it
at dusk.
Although they might remain into early
October, most start migrating along our
ridges in loose flocks in September, stopping each night in another chimney as they
head south.
Eventually, they fly over the Gulf
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Table of Contents for the Digital Edition of Pennsylvania Game News - August 2016
