Mergansers (Plan 15)

Both hooded and common mergansers will nest in tree cavities. These species are found more commonly in northern Pennsylvania. They prefer larger streams, rivers, lakes, beaver ponds, and swamps.

The beautiful hooded merganser will use a wood duck box. Heights above 20 to 25 feet seem to be preferred. Boxes should be placed above water or if on land the entrance should face water.

The common merganser sometimes nests in tree cavities. Boxes successful in attracting this species were placed 15 to 17 feet high in aspen trees on land adjacent to water. This species will nest in a wood duck box if the entrance is enlarged to 5 inches in diameter.

As with wood ducks, nest boxes can be liabilities for these species if no effort is made to predator-proof the boxes. If raccoons are numerous, boxes should not be placed along the waters edge where chances of predation are highest. Either place boxes over water or at least 30 feet from the waters edge on land. Boxes along the waters edge must be predator proofed.

Osprey (Plan 17)

The use of agrochemicals (primarily DDT and related compounds) and habitat alteration caused a serious decline in osprey breeding activity in Pennsylvania. For decades breeding osprey could not be found in Pennsylvania.

In 1979 researchers, directed by Dr. Larry Rymon, at East Stroudsburg University (and sponsored by the Game Commission, Pennsylvania Chapters of the National Audubon Society and the Wild Resource Conservation Fund) developed and implemented a program to restore ospreys to breeding status in Pennsylvania. Since 1986, ospreys are once again breeding in Pennsylvania. At the same time, due to recovering Chesapeake populations, ospreys are expanding their breeding range up the Susquehanna.

Though still classified as endangered, ospreys are (as a result of restoration and natural expansion of traditional populations) once again being seen throughout most of Pennsylvania.

Nest platforms and poles can be constructed wherever there is an adequate supply of fish. Developed or intensively used areas and sites near fish hatcheries should be avoided. Platforms can be placed over water or inland at least 30 feet beyond the waters edge. The height of an inland nest should always exceed the height of any nearby trees or 20 feet whichever is greater. Over water the platform should be more than 15 feet high. For all structures, use metal flashing as a predator guard.

Platforms can be placed on old utility poles in open habitats or on "topped" super canopy pines, or on solid snags adjacent to a shoreline.

(Plan 17) is a diagram of an osprey nest platform. Table 1 is a list of the items needed to construct the platform. An inexpensive alternative is simply to turn a firm, hardwood pallet upside down and, with proper bracing, fasten it to the top of a utility pole. Use a 6 to 8 inch diameter utility pole (preferably a cedar pole). Poles are often available from local utility companies.

All nail and bolt holes are predrilled to prevent splitting. The wire mesh is nailed in the platform. The whole structure is treated with wood preservative and stained brown. Steel braces are bolted to the platform. Lag screws are used to secure the platform to the pole or topped pine tree. Some sticks should be wired into the nest to help stimulate use by ospreys.

Table 1. Materials needed for Osprey Nest Platform: Two 2" x 6" x 12' cedar boards, One 12" x 12" x 1/2" exterior plywood, One 45" x 45" piece of heavy duty wire mesh,  Forty galvanized 40D nails,    Four 1/8" x l"x 30" steel strapping,  Eight 3" x 1/2" bolts with washers and nuts,  Eight 4" x 1/2" lag screws,   Wood preservative and stain.

This information has been derived, in part, from F. L. Johnson and V. Wolniewicz, 1979. Platform for Ospreys. Wisconsin DNR Endangered Species Report, and from JoAnn Frier, Artificial Nesting Structures for Osprey, New Jersey Division of Fish, Game and Wildlife.

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