The double-crested cormorant is a striking, relatively large waterbird, all-black at any distance, often recognizable for its distinctive rapid, close-to-the-water flight. In our township the PLACE to look is any large body of water, including the Trent and Crowe rivers. The TIME to look is especially in fall migration, 09 August- 11 October.
Less often, it may be seen in spring migration, as in two cases on a 16th April and a 10th May. It must be said that the cormorant is much easier to find along Lake Ontario, whether in Toronto or due south of us, at Presqu'ile park. The year 2004 was unique, boasting both of the spring sightings, and nine more sightings in the fall. It may be coincidence, but the bird was made to feel unwelcome at Presqu'ile that spring: in order to reduce the large local breeding population, birds were shot starting on 6th May as part of a cull, and eggs were oiled prior to the start of hatching in mid-June. Cormorants, like herons, will nest in trees, and their acidic droppings kill the host vegetation.
At Presqu'ile park the cormorant is indeed
an abundant migrant and breeding summer resident,
present from early April to early November.
Numbers of nests rose sharply during the 1980s
(LaForest, 1993, pp.36-39).
In the Kawarthas, to the north and west,
the bird is (or was) but an irregular visitor,
with extreme dates of 27 April to 20 November
(Sadler, 1983, p.36).
Breeding bird surveys across the province
can illuminate and update these observations.
Cormorant numbers around the Great Lakes
have risen rapidly since 1973. For nesting,
in southeastern Ontario, the bird was virtually confined
to the north shore of Lake Ontario
(Cadman et al., 1987, pp.44-45).
However, the birds favour the security of islands,
as at Presqu'ile, including islands on some smaller
inland lakes, as well as along the shorelines
of Lake Ontario and Georgian Bay
(Cadman et al., 2007, pp.152-153).
Cadman,MD, Eagles,PFJ and Helleiner,FM (1987) Atlas of the Breeding Birds of Ontario. Federation of Ontario Naturalists and Long Point Bird Observatory, published by University of Waterloo Press, 617pp.
Cadman,MD, Sutherland,DA, Beck,GG, Lepage,D and Couturier,AR (editors) (2007) Atlas of the Breeding Birds of Ontario, 2001-2005. Bird Studies Canada, Environment Canada, Ontario Field Ornithologists, Ontario Ministry of Natural Resources, and Ontario Nature, 706pp.
LaForest,SM (1993) Birds of Presqu'ile Provincial Park. Friends of Presqu'ile Park / Ontario Ministry of Natural Resources, 436pp.
Sadler,D (1983) Our Heritage of Birds: Peterborough County in the Kawarthas. Peterborough Field Naturalists / Orchid Press, Peterborough, ON, 192pp.