Nature Notes for August 29, 2014
“I saw a flock of birds flying over my yard, but I don’t know what
they are. They are bigger than a swallow with a white blotch on each wing and
their flight in like bats. Would you have any idea what they are?”
Several times in the past couple of weeks, I have received queries
similar to the one above. I wish all bird identification questions were as easy
as this one. The birds in question were Common Nighthawks. There have been a
number of recent reports of migrating Common Nighthawks and I’ve seen them over
my house in Port Hope.
Common Nighthawks aren’t hawks at all, but are part of a group
known as nightjars. For reasons that no one really knows, this group is
sometimes called goatsuckers. It was thought that they entered barns and sucked
on the teats of goats. This is, of course, a myth, but the name has stuck.
They are aerial foragers which hunt for flying insects primarily
at dawn and dusk. For the size of the bird, they have a very large mouth with
rictal bristles. These are similar to the whiskers on a cat and, combined with
the wide mouth, are very effective in scooping flying insects from the air.
The colouring of Common Nighthawks is a mottled mixture of shades
of brown. Since they prefer to nest on the ground in open sites, this
coloration provides good camouflage. The white spots on the wings aren’t
visible when the bird is perched.
Their natural nesting habitat is in open areas, such as those
provided after a forest fire, or on rocky outcrops in the Canadian shield. Their
nests can be found in openings in the forest due to fires or clear cuts, on
sandy blowouts and in old, unused gravel pits.
Since the mid-1800s, they have also been found nesting on flat
gravel roofs in urban areas. This type of roof is no longer in favour with
builders, so this habitat has reduced somewhat. Initially, the rooftop
locations provided protection from predators such as foxes, raccoons and
skunks. However, urban gulls and crows have discovered the nighthawk nests and
are now major predators of roof-nesting nighthawks.
In the spring, Common Nighthawks are most often detected by sound.
Their call is a loud “peent”. The males have a spectacular display flight. The
will fly to a great height and plummet towards the ground and a waiting female.
Just when it seems that they will crash, they pull up, which causes a loud
booming sound from the wind forced through their wing feathers. This boom can
be heard over quite a distance and has contributed to another colourful name
for this species: Bullbat. Bull was because of the loud booming sound and bat
because of the style of their flight.
As with all the aerial foragers, their populations are showing
declines. In the twenty years between the two Ontario Breeding Bird Atlases,
there was a significant decline in the observations of Common Nighthawk. They
are listed as “Threatened” by the Committee on the Status of Wildlife in Canada
(COSEWIC) and as of “Special Concern” by the Ontario Ministry of Natural
Resources (OMNR).
Their breeding range includes most of North American south of the
tundra. The ones that are passing through Northumberland now are heading to
wintering areas in South America, as far south as northern Argentina.
Probably by the end of this week, when this article appears in
print, most of the Common Nighthawks will have moved through the area.
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Presqu’ile Provincial Park is holding the 30th annual
Monarchs and Migrants event over Labour Day weekend. Check the Friends of
Presqu’ile web site http://www.friendsofpresquile.on.ca/
for the complete schedule of events. They include guided bird hikes, bird
banding and Monarch butterfly tagging.
On September 20, Alderville Black Oak Savanna hosts Prairie Day, a
project of the Rice Lake Plains Joint Initiative.
