Nature Notes for November 23, 2012
This winter, southern Ontario birders are enjoying the
opportunity to see some of the northern finches which don’t visit us on a
regular basis. Since the primary winter food of finches is seeds, they can
winter in the northern forests if there is an abundant seed crop.
Last summer’s dry weather did not produce much seed, so the
finches are on the move. This movement is not a regular migration, rather it is
termed an irruption. Irruptions are usually caused, as in this case, by a
shortage of food.
Two of the large finches, Pine Grosbeak and EveningGrosbeak, are being found just now in Northumberland County. Both of these
species nest in the Boreal Forest right across North America.
The Pine Grosbeak is a Holarctic species, that is it occurs
in the forests of northern Europe and Asia in addition to North America. It is
a bit smaller than a robin, quite plump with a strong bill and smallish head.
Designers of Christmas cards like to show the male of this species, since it is
a pinkish-red. The wings are black with strong white wing bars.
None of the birds found last weekend on a Willow Beach FieldNaturalists outing were adult males, so none were red. The females and young
birds are primarily gray, with a bronze colour on the head and rump.
Although Pine Grosbeaks tend to call when they are flying,
they are very quiet when they are feeding. The ones we saw were feeding on the
seeds of the non-native Russian Olive. One of their favourite foods is the
fruit of crab apple trees. They are actually eating the seeds in the middle of
the apples, not the fruit. They eat a variety seeds from fruiting trees and
shrubs including European buckthorn, high bush cranberry, mountain ash and
dogwood.
Evening Grosbeaks are a bit smaller than Pine Grosbeaks,
also quite plump with a big head and massive seed-cracking bill. They are
yellow, black and white, with the males brighter yellow than the females.
In the mid-twentieth century, they were very abundant in
Ontario thanks to outbreaks of spruce budworm which they fed to their young.
Since 1980, the population seems to have declined because there have been no
severe outbreaks of spruce budworm.
This fall, though, a number of observers have found them at
their bird feeders. Several of these reports have been from the Northumberland
and Ganaraska Forests, but there has been at least one report from within the
urban part of Port Hope.
Evening Grosbeaks like sunflower seeds, so will frequent
feeders if they find them. When not at feeders, they are known to wander widely
in search of food. In this area, they feed primarily on Manitoba maple seeds
and staghorn sumac.
A large part of their summer food is the seeds of wild
cherries. Their beaks are strong enough to crack them.
As with all irruptive species, it takes a bit of luck to
find the birds. Perhaps you will be lucky enough to have one of these visitors
in your backyard or at your feeder this winter.
