March 2013 - Migration Begins

Nature Notes for March 29, 2013

The month of March marks the change of season in the bird world. There is so much to report!

Presqu’ileProvincial Park held their annual Waterfowl Festival on the weekend of March 16 and 17.  This event celebrates the arrival of migrant ducks from wintering grounds on the Atlantic seaboard. Most stage here to feed before continuing on to nesting grounds further north. Since most lakes further north are still ice-covered, there are still lots of water birds around.

The first arrivals are diving ducks. Some species such as Long-tailed Ducks, GreaterScaup, Common Golden-eye, Bufflehead and White-winged Scoter winter on the Great Lakes, but now they are joined by more birds which have wintered further south. The flocks now include Lesser Scaup, Redhead, Ring-necked Ducks, Canvasbacks and all three Mergansers – Common, Red-breasted and Hooded.

Many of these diving ducks can also be viewed in Cobourg Harbour. There have been two Ruddy Ducks here, too. This is an uncommon migrant in this area.

Among the divers, there are often American Wigeon, Northern Pintail, and Gadwall. These are dabbling ducks which tip up to feed but don’t dive below the surface. As the ice melts in the marshes, other dabblers such as Green-winged Teal, NorthernShoveler and finally, Blue-winged Teal, will arrive. Many dabblers make use of any small pond or flooded field.

Thousands of Canada Geese could be found this week foraging in last year’s harvested corn and soybean fields. They often spend the night on Lake Ontario, so at certain times of the day, there are big flocks travelling between farm fields and the lake. Last Sunday, the huge flock of geese on Garden Hill pond included one Snow Goose. There were also three Cackling Geese, a small version of the Canada Goose which has recently been designate as a separate species.

This year, there have been Tundra Swans with the geese in larger-than-usual numbers. The usual flight corridor for Tundra Swans is further west, through Long Point on Lake Erie. This spring’s west winds have pushed the birds further east. The large white birds are hard to miss when they are present. Tundra Swans (formerly called Whistling Swans) are native swans which spend the winter in the Chesapeake and Delaware Bay area on the eastern seaboard. These birds make very long migrations north and west. Some nest as far north as the NorthwestTerritories.

The first obvious arrival of landbirds was on March 10 this spring. Red-wingedBlackbirds, Common Grackles and American Robins all appeared on that date, which is about the time they are expected. There was a dump of heavy snow after that date and a robin moved into the multiflora rose bush along my driveway. The rose hips assured his survival when he couldn’t forage on the ground. Since that first arrival, the weather has been cold with north winds, so there hasn’t been much more landbird migration.

I saw my first Killdeer last Sunday (March 24), although there have been a few earlier sightings reported in the area. A few Turkey Vultures have been seen patrolling the roads, the earliest on February 28. These, too, are recent arrivals from the south.

AmericanWoodcock have appeared at Presqu’ile. These odd looking birds probe with their long beaks into the earth to find earthworms to eat. The cold nights this week cannot have made this very easy.

With all of the new arrivals, it is easy to overlook the lingering “winter” birds. American Tree Sparrows have begun to sings. It will not be long before they leave for the taiga. There have still been a couple of Common Redpolls visiting my feeder. They will depart for the tundra soon. Dark-eyed Juncos are also singing their trilly song. Most of them leave Northumberland County to breed although they don’t go as far, only to the Canadian Shield.

For the next two months, the bird species mix may change almost daily. I urge readers to explore their local patch to see what birds are around.

Bald Eagles in Northumberland County

Nature Notes for February 22, 2013

What better way to spend Family Day than birding? A friend told us about an adult Bald Eagle that had been seen regularly along the Rice Lake shore west of Roseneath. These huge birds are always a treat to see, so my husband and I went in search of it. Alas, we were unsuccessful in this location.

We decided to check at Hastings where eagles are often seen in winter. When we arrived, a sub-adult was circling over the river west of the dam over the Trent. At this age, Bald Eagles are mostly brown with varying patterns of white on the wing linings, belly and tail. Sometimes in this plumage, they are mistaken for Golden Eagles. The Bald Eagle has a much bigger head than the Golden. The white on an immature Golden is restricted to the base of the tail and and the base of the primaries. The white on a Bald Eagle is much more variable as to amount and location.

On a hike along the Trans-Canada Trail east of Hastings, we found two more, this time adults with complete white head and tail. They don’t attain this plumage until they are at least four years old. One adult was perched in the sun on one of islands in the river. While we were watching, this bird took flight. Later, we saw two adults flying together, in what was probably a mating display.

Bald Eagles primarily eat fish and carrion. They have been known to harass Osprey until they drop their fish, and then swoop in to catch the fish. The smaller Osprey can do little about this. They can hunt and kill water birds, rabbits and other small mammals. My brother-in-law, who lives in New York State, reported this winter of eagles on the Croton River feeding on American Coot that had become marooned in small areas of open water during a sudden freeze-up.

They build massive stick nests. One in Ohio was reported to weigh almost two metric tons. It was used for 34 years until the tree blew down.  In Ontario, eagles usually nest in trees, although where there are no suitable trees, they will nest on cliffs or even on the ground.

Bald Eagles are long lived birds. The longevity record (from the records of the Bird Banding Lab) is 32 years 10 months in the wild  and 36 years in captivity.

Bald Eagles populations declined dramatically in North America in the mid-twentieth century due to pesticides such as DDT. Eagles are at the top of the food chain, so the pesticides are concentrated in these birds. DDT and related chlorinated hydrocarbons alter the birds’ calcium metabolism in a way that results in thin eggshells. These thin-shelled eggs could not support the weight of the incubating birds and these eggs would break.

 Bald Eagles were listed as endangered by the Ontario Ministry of Natural Resources in 1973.       

Since the early 1970s, when DDT was banned in North America, eagles are making a slow recovery. Studies carried out by BirdStudies Canada on nesting eagles in Ontario indicate that, although Bald Eagles are recovering, they don’t seem live as long or raise as many chicks as was the case pre-DDT. This study is ongoing, so in time, it may determine the reasons for this.

At present, OMNR has downgraded the threat to Bald Eagles, although they still remain a species of “Special Concern” in the province.

If you travel to Hastings over the next few weeks, perhaps you will be lucky enough to spot one.