Pennsylvania Game News - August 2021 - 62

of all species with significant populations,
nighthawks had the greatest decline
in block detections between the
first (1983-89) and second atlasing
(2004-2009) of breeding birds. The
number of blocks dropped 71 percent
with only four confirmed records of
nests containing eggs or young.
For this reason, the common nighthawk
is now considered " Near Threatened "
by the Ornithological Technical
Committee of the Pennsylvania
Biological Survey, and a Pennsylvania
Species of Greatest Conservation Need
in the Pennsylvania Wildlife Action
Plan.
Douglas A. Gross, in a 2013 article
for the American Birding Association
titled " Decline of the Bullbat, " recalled
watching several nighthawks over his
yard in Bloomsburg on summer evenings
when he was a youngster in the
1960s. He believed they nested on the
flat roofs of mills in the town. However,
he returned to his old neighborhood
several times during the second
atlasing period, and didn't see or hear
a single nighthawk.
" They're gone, " he wrote, and " the
community is poorer for it. "
Researchers hypothesize several reasons
for their decline, including lower
numbers of flying insects because of
pesticides and habitat loss such as open
woods in rural areas and flat gravel
roofs in urban localities.
Throughout North America, nighthawks
use a number of habitats, from
rock outcrops to woodland clearings.
All are open and flat enough to hold the
two white-to-pale gray speckled eggs
the females lay on the ground.
But in many places nighthawks are
dependent on flat, gravel roofs, and as
they're replaced by rubber roofs, night62
hawk
eggs no longer are camouflaged.
The eggs also roll easily on rubber
roofs, and because rubber gets hotter
than gravel, higher temperatures might
damage the eggs.
Daniel W. Brauning, in the first Atlas
in Pennsylvania,
of Breeding
Birds
wrote that common nighthawks were
" almost totally restricted to man-made
structures (for nesting) in Pennsylvania. "
Grove
also reported nesting sites at
a former surface mine area in northern
Clinton County and on a newly grassed
area that had been denuded by industrial
pollution in Carbon County. Other
suspected nesting sites were found on
former surface mines in Centre and
Clearfield counties, and in the coalfields
in Schuylkill, Lackawanna and
Luzerne counties.
Because of a long migration back
from Brazil, where most common
nighthawks winter, they don't arrive in
Pennsylvania until May.
The male performs courtship flights
in which he flies down to within a few
yards of a female then turns sharply upward.
His vibrating feathers produce a
booming (or bulling) sound. Then the
male lands beside her, spreads his tail,
and sways back and forth, displaying
his swollen throat and large white neck
patch, while he emits guttural croaking
notes through his closed beak. He also
flies over the female repeatedly and
peents before mating.
He continues these flights and displays
throughout the time his mate
selects the nest site, lays her eggs, and
incubates them 16 to 20 days, usually
in late May or early June in Pennsylvania.
Once his offspring hatch, the male
Pennsylvania Game News - August 2021

Table of Contents for the Digital Edition of Pennsylvania Game News - August 2021
