by: Glen Rhodenizer and P.J. Austin-Smith
September 1980
Ospreys or fish hawks are large fish-eating birds that haunt the calm, summertime waters of coastal bays and inlets as well as food-rich inland lakes and rivers. These strikingly patterned brown an white "hawks" hunt for their prey by flying over the water at heights ranging from 40 to 100 feet. After spotting a fish near the surface, the hover momentarily, then, in a spectacular dive plunge feet first into the water.
The ideal nesting site for an osprey is the top of a tall dead tree close to water. If such trees are not available they will use live trees with dead tops, or man-made structures such as telephone poles or wharf pilings. If their food supply is abundant but nesting sites are limited, they may nest a mile or more away from water.
In several regions of North America, loss of habitat, nest disturbances, wanton killing and chemical food contamination have all contributed to major declines in osprey populations. Programs designed specifically to prevent any further population losses by protecting and improving breeding habitat are now underway in both the United States and Canada.
Ospreys are common in Nova Scotia during the spring and summer breeding season. They are most numerous along the mainland Atlantic coast where they nest primarily on islands, but occasionally on isolated headlands or close to estuaries. The north shore (Pictou and Antigonish) also hosts sizeable numbers; but inland and on Cape Breton Island, osprey are much less numerous.
Where there are abundant nesting sites near rich fishing grounds, osprey may nest in such numbers as to form a colony. In Lunenburg County, one such loose colony of eight nesting pairs has become established on the main electrical transmission line in the Indian Path area near Riverport. The double poles, joined by twin cross-members that support the high voltage wires serve admirably as nest sites, particularly those on higher ground. Ospreys prefer a sweeping view of the surrounding land and water. Unfortunately, there is a risk of costly power interruptions due to material falling from the nests or from large sticks being accidentally dropped by the birds during their nesting activities.
To reduce this possibility, a joint project, Nova Scotia Department of Lands and Forests and the Nova Scotia Power Corporation, decided in the fall of 1979 to cost-share the construction of artificial nest sites. Eight of these nesting platforms, consisting of wooden discs mounted on 40-foot poles were erected by the Power Corporation along the power line corridor, one in the immediate area of each existing nest but far enough to one side not to interfere with power transmission. After installation, the existing power line nests were removed in December. At this time the birds were wintering in the Caribbean area or in Central and South America. To make these locations as attractive as possible to the returning birds, some of the old nesting material was then placed on the new nesting structures.
On April 4, 1980, the first ospreys were observed along the Indian Path power line corridor. By May 2nd the birds had built well-formed nests on six of the substitute nesting platforms. One site was unoccupied, and the remained so throughout the breeding season. At one site the birds ignored the new nest platform and rebuilt on the power line pole. A final mid-July survey of the colony revealed that ten young ospreys had hatched from six nests, while one nest had failed. These results indicate that the project was successful, not only in reducing the number of birds nesting on the power line but also in maintaining suitable nesting conditions for the production of young birds.
Ospreys relocation 1979 is an example of how both public and private agencies can work together successfully to protect and conserve wildlife resources. Particularly deserving of credit are N.S. Power Corporation employees Keith Wentzell, Clyde Brown and John Gow, Donald Richardson of National Sea Products and Sheldon Mossman of Riverport Sea Foods were also helpful.