Common Nighthawks on the Move

Nature Notes for August 25, 2017

Just as the light is fading so that nothing is very clear, readers may see a bird with a fluttery flight passing overhead. This bird will appear as a dark silhouette with an obvious white bar on each wing. It has long, pointed wings and a long notched tail. The flight style is reminiscent of a bat, although the bird is larger than a robin.

Common Nighthawks may be seen in late August as they migrate south.

Photo © Rob Lonsberry Photography

This is the time of year when Common Nighthawks are moving south from their breeding grounds to South America where they spend the winter. Common Nighthawks breed throughout North America and into Central America.

Despite their name, they are not hawks at all, but member of the nightjar family, another odd name. At one time, they were called “goatsuckers” because of a myth that they entered barns at night and sucked goats milk.

They are a mottled brown, tan, white, and black, the perfect coloration to blend into the background when they roost and nest on the ground.

Their preferred nest sites are open, vegetation-free habitats, including dunes, beaches, recently harvested forests, burnt-over areas, logged areas, rocky outcrops, rocky barrens, grasslands, pastures, peat bogs, marshes, lakeshores and river banks. In Northumberland County, they nest in open areas of the Northumberland and Ganaraska Forests.

When we were in Saskatchewan last summer, we found them roosting on fence posts during the day at Old-Man-On-His-Back Nature Reserve. We had never seen them do this anywhere in the east.

In urban areas, they will nest on flat gravel roofs. Unfortunately for the nighthawks, the urban crows and gulls have discovered this and often depredate the nests. A nighthawk eggs is a good meal for a crow.

Common Nighthawks don’t build a nest. They usually lay two eggs which are laid directly on the ground. The young don’t stay long around the nest.

Since Common Nighthawks are active only at dawn and dusk, when visibility is poor, and they are very cryptically coloured, they are very hard to study. Both Ontario Breeding Bird Atlases commented on how difficult it was to confirm nesting of this species.

In the spring, they can often be found by their vocalisations, a “peent” given in flight. In the spring, the male has a spectacular display. He calls, circles and “booms” as he swoops down over his potential mate. The booming is caused by air passing through his vibrating primaries.

Common Nighthawks are aerial foragers. They east almost exclusively flying insects – moths, mosquitoes, flying ants – and can sometimes be seen hunting under street lights. Although their beaks aren’t very big, when they open their mouths, they have a huge gape. This is an excellent adaptation for scooping up insects from the air.

Unfortunately, like all aerial foragers, their population seems to be declining. It is listed as of “Special Concern” by Species at Risk in Ontario and as “Threatened” by Committee on the Status of Endangered Wildlife in Canada.

The causes of the decline of Common Nighthawk populations are unknown. It may be related to the decline of the insect populations on which this species preys. Other factors that may have contributed to the declines probably include habitat loss and modification. The increased predator population (specifically Domestic Cats, Striped Skunks, Raccoons, American Crows, and Common Ravens) may contribute to this species’ decline, particularly in urban areas. Other possible factors include collisions with motor vehicles and climate change.

Although Common Nighthawks do not occur in as large numbers as in the past, readers still have a good chance of seeing some in the evening as they migrate towards South America.

High Water Levels - bad for some birds, a boon to others

Nature Notes for July 28, 2017

High water levels along Lake Ontario have flooded beaches and washed out my favourite walking trail. Farmers are having difficulty both planting and harvesting crops because of wet fields. Boats are unable to use Port Hope’s harbour facilities.

But how has the wet spring and summer affected birds?

Last year at this time, I was writing very excited columns about Piping Plovers, an endangered species, nesting for the first time in 100 years at Presqu’ile Provincial Park. This spring, the male that nested there last year came back in May. (Since he was colour banded, he could be identified.) Instead of a wide sand beach, he was faced with a swampy area. What had been dry sand last year was covered with water right up to the vegetation behind the “beach”. He stayed around for about a month, but the water didn’t recede, so he left for places unknown. There was no place for a bird which required a sandy beach on which to nest.

A pair did nest in Prince Edward County at North Beach Provincial Park, not far from Presqu’ile as the plover flies. This pair laid four eggs, which hatched. However, at last report, none of the chicks were still alive. One of them was seen being taken by a gull.

There were four nesting attempts at Darlington Provincial Park in Oshawa. It is uncertain whether these were all by the same birds. Three attempts were unsuccessful because they were washed away by storms after eggs had been laid. The fourth attempt laid 4 eggs of which 3 hatched. At this writing, the male and two chicks remain. The female has left the beach, which is normal behaviour for this species.

With the population of Piping Plovers so low on the Great Lakes, loss of any nest is really bad news for the species survival.

Other birds that nest on marshes have not had a good breeding year either. I have noticed many fewer Canada Goose goslings around town than in most years. Although I didn’t see it, I suspect that many of these nests were destroyed by the high water. The same probably goes for many duck nests and Mute Swans. Geese and swans nest on mounds of vegetation, such as an old muskrat lodges in marshes. These nests would have been very prone to flooding.

Other marsh birds, such as rails, gallinules and bitterns have also had trouble finding dry enough spots to nest. A friend who lives near Presqu’ile marsh has had as many as five American Bitterns hanging around his property. This property is usually a dry grassy field. This year, it is an extension of the marsh.

Although the high water levels have been bad for some species, returning shorebirds have found that the flooded beaches provide good foraging. By July, many Arctic nesting shorebirds are already moving south again. At Presqu’ile, they didn’t find a beach. Instead, there is a low ridge of sand at the water’s edge and behind this ridge is a series of shallow ponds. These provide abundant invertebrates on which the shorebirds feed.

Among the species using these ponds were Wilson’s Phalarope, Stilt Sandpiper, Sanderling, Lesser Yellowlegs, Semipalmated Plover and Pectoral Sandpiper.

These shorebirds aren’t being disturbed very much by humans because rubber boots are required to access the area.

Common Black-headed Gull, one of the unusual gull species present this summer at Cobourg.

Photo  © Rob Lonsberry Photography

Earlier in the summer, huge number of gulls lingered at Cobourg because of the flooded beach and sandbars. Among the usual species were several rare ones such as Little Gull, Common Black-headed Gull, Laughing Gull and Black-legged Kittiwake.

While the high water was detrimental to some species, it was a boon to others.