Nature Notes for August 24, 2012
This week, the southward migration of landbirds is beginning
to be evident. In my garden, Red-breasted Nuthatches can be heard giving their
distinctive call. Although this species does nest in Northumberland County,
they do not nest in my neighbourhood in Port Hope. These birds might have come
from the Boreal forest. This species often moves south because of a shortage of
their preferred food, conifer seeds, in the north.
An early movement of Red-breasted Nuthatches often presages
an influx of finches (Pine Siskin, Common Redpoll, Purple Finch, Red and
White-winged Crossbill, Pine Grosbeak and Evening Grosbeak) later in the fall.
Birders are always trying to predict these influxes or “irruptions”.
Another species which moves south in response to food
shortage is Blue Jay. Ontario’s dry summer may not have produced enough acorns
and beechnuts, their staple winter food, for many to stay over the winter. It
will be interesting to see whether we see huge flocks of jays migrating this
fall. The few that do overwinter will almost certainly use bird feeders.
Fall migration is a much more leisurely affair than the
northward one in the spring. As long as the birds can find food, they can stay.
There is not the same pressure to breed and raise young while food is abundant.
Most of the small landbirds migrate at night. Although I
listened at my open window last night, I couldn’t hear any. The weather was
clear so they may have been flying too high to be heard easily.
In woodlots, mixed species flocks of warblers could be found
this week. A good way to find these flocks is to listen for the Black-capped Chickadees. Often, they will be accompanied by warblers, vireos, flycatchers,
and nuthatches. Since the chickadees are much more vocal than the warblers, they
make these flocks easy to find.
In a few places, flocks of swallows of several species can
be found gathering on roadside utility wires. Since swallows feed almost
exclusively on flying insects, they need to go south before the weather gets
too cold for the insects. Our largest swallow, the Purple Martin, winters in
south America, as far south as Brazil, so they also have rather a long journey
to make.
Bobolinks, too, winter in South America. They are now at the
peak of their migration. During the day, their “pink” call notes can often be
heard as they are passing overhead. This evening (Aug. 21), a large flock was
seen feasting on weed seeds in a rather weedy soybean field just west of Port
Hope.
Many shorebirds are being reported from the beach at
Presqu’ile Provincial Park. This is the best place to see large numbers of
shorebirds in Northumberland. The highlight so far has been a Willet, a large
shorebird that breeds in the western prairies. Small numbers of shorebirds may
be seen anywhere along the lakeshore where the beach is undisturbed and there
has been a deposit of algae. Shorebirds feed on the little invertebrates that
inhabit these algae mats.
Shorebird southward migration begins by early July. The
adults do not take any longer than necessary on their northern breeding grounds
before turning around and moving south again. The young of the year will follow
when they can fly well enough.
There are two events coming up that celebrate migration:
September 1 and 2, Presqu’ile Provincial Park’s Monarchs and
Migrants weekend, www.friendsofpresquile.on.ca
September 8, Alderville Black Oak Savanna Prairie Day, 8467
Cty. Rd. 18,1.5 km. west of Cty. Rd. 45, www.ricelakeplains.ca.
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