American Avocets Visit Presqu'ile

Nature Notes for April 29, 2011

You could hear the amazement in the voice on the answering machine message which I received late on Easter Saturday afternoon. At about 12:30 that day, after the morning rain had stopped, Doug McRae decided to visit Presqu’ile’s beaches to see what might have been grounded by the storm.

He found a treasure: American Avocets on Beach 3. There was not just one, but 32 birds! We decided that this was a sighting worth chasing and immediately decamped for Presqu’ile. Arriving at about 5:30 p.m., we crept carefully down the access road to Beach 3 and out onto the beach. There they still were, sleeping and preening on the beach near the water’s edge.

American Avocets are large, quite handsome shorebirds. They have black and white bodies with cinnamon neck and head. Their legs are so very long and thin that it almost seems impossible that they could support the weight of the bird. The bill is very long and upturned.

These birds are rare migrants in Ontario. If they are seen in the province, they are usually seen in the south-western Ontario and usually in ones and twos, not in such a large numbers. This flock  was also seen in a somewhat unusual place. They are more often found in wet fields, shallow marshes and sewage lagoons. Most nest in the prairie pot holes in the central part of North America.

The avocets stayed at Presqu’ile for the afternoon and into the evening. Thanks to modern communications, we learned of their departure at about 8:15 p.m., only minutes after they took flight.

This is the time of the spring for such avian surprises. I receive many e-mails and phone calls about “unusual” birds. “Is it possible that I have an Eastern Towhee in my garden?” was one query. Indeed it is. This large sparrow is quite obvious when it’s around. The male has a black head, bib, back, and tail, rufous sides the same colour as a robin’s breast, white underparts and a few white spots on the wings. It scratches at the ground with both feet at the same time, behaviour this observer described as a dance.

Although it is unlikely that an Eastern Towhee would stay to nest in a garden in town, they do nest in Northumberland County. They favour old field habitats. They used to be more common when agricultural fields were smaller and separated by hedgerows.

At this time of year, the birds around us are changing constantly. Songbirds are beginning to arrive. On a walk around today (April 26), after the rains stopped, there were many, many Yellow-rumped Warblers in evidence. They were accompanied by the first big push of White-throated Sparrows and some Hermit Thrushes. Many of these birds winter in the southern U.S.

The first few migrants from the tropics, such as Black-throated Green Warbler, Northern Parula, and Black-and-white Warbler, have also arrived. Many more will probably have arrived by the time this column is published.

You have to be lucky to find rarities, such as a flock of American Avocets in eastern Ontario, but I encourage readers to really look at the birds around you. You might be treated to the unexpected.

Turkey Vultures

Nature Notes for April 15, 2011

The April 7 issue of NorthumberlandToday.com carried a great photo of a Turkey Vulture, so I thought that readers might be interested in learning a bit more about this big bird.

Because of its size, it is often noticed by people who don’t usually pay much attention to birds. It is migrating back into our area now. At this writing, 6,336 Turkey Vultures have been counted this spring by the hawk watch at Beamer Conservation Area, which sits atop the Niagara Escarpment at Beamsville. This is a concentration point for northward migration of birds which don’t like to fly over water. Once safely past the lower Great Lakes, the birds fan out over the province.

During the southward migration in the fall, many can be seen flying west along the Lake Ontario shore. In parts of the southern U.S., Turkey Vultures are year round residents.  Because they have no feathers on their heads, vultures must withdraw from the northern part of their range when the temperatures drop. They are found throughout Central and South America, but nothing is known about where exactly the Ontario birds spend the winter.

In flight, the Turkey Vulture tips its wings up, so that its silhouette is a shallow V. It can fly long distances without flapping, riding the air currents, tipping from side to side.

Although Turkey Vultures look like they should belong to the hawk family, recent DNA work has found that they are more closely related to storks.

If you think that Turkey Vultures didn’t used to be in this part of the world, you are right. Although the earliest record for Northumberland County was in the early 1930s, sightings of vultures didn’t become an annual occurrence until the 1960s. The first record for Presqu’ile was in 1979 and it was only in the 1980s that it became a common bird. The twenty years between the two editions of the Breeding Birds of Ontario documents this range expansion.

Following World War II, the interstate highway system in the U.S. was expanded. Ontario, too, has built many highways in the past sixty years. This provided an unexpected (by the road builders) bonanza of food for the vultures: road kill. Dead raccoons, skunks, woodchucks, turtles and in some places, deer, provide an abundant resource for an animal which feeds on carrion.

As well, global warming over the past century has probably contributed to the Turkey Vultures’ range expansion.

With their red naked heads, they are well-adapted to feed on carrion. It is much easier to keep a bare head clean than it would be to keep feathers in good shape when dead things are the primary food. Their gut is able to neutralize toxins of decomposition which would harm other animals.

Turkey Vultures are thought to be one of the few birds which has a well-developed sense of smell, thought to help them find carrion. The part of the vulture brain which is involved in smell is larger that it is in most birds.

Turkey Vultures don’t really build much of a nest. They nest on the ground, in caves, on cliff faces, in hollow logs or trees and in abandoned buildings. The same nest site may be used for many years.

They typically lay 2 eggs and both the male and female incubate. As with most large birds, the incubation time is quite long (38-41 days) and the chicks can remain in the nest up to 88 days.

The young birds are fed regurgitant. That is, the adults eat and return to the nest where the youngsters stick their heads down the adults’ throats to get their meal. Turkey Vultures don’t have strong enough legs or beaks to carry large food items back to the nest.

 They are pretty amazing creatures, able to make a living on food that would kill most other animals – one of nature’s major recyclers.

Hybrid Goose at Garden Hill

Nature Notes for April 1, 2011

Among about 2000 Canada Geese on Garden Hill pond was one that looked different. At first glance it seemed to be a Greater White-fronted Goose. It had the pink bill and white around the base of the bill.

However, on closer inspection, it lacked a white line on its side and there were faint white patches on the cheeks in the place where a Canada Goose is white. The consensus of those who saw this bird was that it was a hybrid between a Canada Goose and a Greater White-fronted Goose.

Studying this bird was a challenge last Sunday. Just finding it amongst the many Canadas was like playing a moving “Where’s Waldo”. Many of the geese were sleeping, so had their heads under their wings, obscuring the important field marks. Many had their backs to observers and observers were facing into a howling wind. But is was seen well enough by a couple of observers to confirm its identity.

The Sibley Guide to Birds states that these hybrids are “seen occasionally.” These two species are not even in the same genus and I couldn’t find references which inwww.allaboutbirds.org/.../Northern_Pintail/dicated whether the hybrids would be able to reproduce.

Perhaps because waterfowl are big birds, hybrids are seen relatively frequently. During this past winter, two hybrid ducks were reported from Presqu’ile, one a Hooded Merganser crossed with Common Goldeneye, the other a Mallard crossed with Northern Pintail.

A more common hybrid occurs between Mallards and American Black Ducks. In the early 1970s, birders along the eastern seaboard started to notice American Black Ducks which showed a white wing marking characteristic of a Mallard.

These two species are in the same genus and they readily hybridize. Their offspring are fertile. In time, the Mallard genes may swamp American Black Duck genes and American Black Ducks may disappear as a species. In the twenty years between the two Ontario Breeding Bird Atlases, the number of confirmed breeding records for American Black Duck had reduced quite noticeably.

Among landbirds, hybridization between Blue-winged and Golden-winged Warblers is well-known. Prior to European settlement, the breeding range of the two species did not overlap. With clearing of the eastern forests and subsequent regrowth of shrubby fields, the Blue-winged Warbler started to move north. Where their range met that of the Golden-winged Warbler, the two did interbreed.

These two species are also closely related and in the same genus. The favoured habitats of these two are also very similar.

The offspring of these pairings are distinctively marked and were once thought to be separate species – Brewster’s and Lawrence’s Warblers. These names are now used to indicate particular forms of the hybrids.

Blue-winged Warblers are more aggressive than Golden-winged and over time, tend to displace Golden-wings. The Golden-winged Warbler is now considered an officially designated “threatened” species.

These are just a few examples of the several bird species which are known to hybridize.

Determination of species is a tricky thing. DNA analysis of birds is changing long-held ideas about the relation of one species to another. It has also found that some species which look very similar are actually different species. This all makes things very challenging for the field observer.