Osprey platform goes to new heights
By Jean Ruzicka
Ospreys will return this spring to discover a new penthouse suite on the Highway 34 pole.
Thanks to Park Rapids Cub Scout Pack 58, who constructed the platform, and Great River Energy, who was granted permission to relocate the nest a year ago, ospreys will have new digs.
Christine Herwig, a Department of Natural Resources nongame specialist, explained this osprey nest is not an exception.
Many ospreys nest on man-made structures. From time to time, these structures need to be replaced or in other cases, the nests may be causing a fire hazard or power issue. When this happens, a state permit to remove the unoccupied osprey nest is issued to the power company.
While not required to, some power companies go above and beyond their duty to help the birds and put up a new structure for the birds.
“Great River Energy cares about the environment,” said supervisor Carole Schmidt. “We work extensively with the DNR to ensure we protect wildlife and make as smooth an adjustment as possible.”
Ospreys generally migrate from September through March.
When osprey build their nests on power line structures, there are a number of reasons for concerns, Lori Buffington of Great River Energy explained. Nests on wood structures concentrate fecal matter and moisture on the cross arms, which accelerates decay. Because of this decay, the arm may eventually fall and drop the wire, possibly causing outages, fires or electrocution if someone is near.
Just last year Great River experienced an outage caused by an osprey nest. Sticks fell onto the wires when the ospreys were building their nest on one of the structures.
The DNR issued 40 permits to remove nests in 2014. Erecting a platform either on the existing pole or a pole nearby is beneficial for the birds, as well as power companies.
For the companies, putting up a new structure eliminates need to issue a new permit every year, reduces the potential for future hazards or problems related to the nest, and may reduce costs associated with the installation of additional deterrent devices or conducting annual removal, according to the DNR.
For the birds, a platform may provide a more attractive nesting structure. It also provides a much safer habitat for the birds to build their nest and raise a new family of young ospreys.
Mate fidelity is high, 60 to 70 percent per year, according to Herwig. Sometimes a mate may die and they seek another, or as it happens sometimes, if a pair is unsuccessful at breeding, they may seek a new mate.
Generally, the males return a few days before females. Pairs often return to the nest from previous years.
Resurgence of the fish hawk
The osprey was once known as the “fish hawk” because of its diet of fish.
At one time, ospreys nested across much of North America from Canadian lakes to oceanfront beaches from Maine to Florida.
With the advent of the use of “persistent pesticides” like DDT following World War II, ospreys also became victims of eggshell thinning. DDT affects calcium metabolism associated with eggshell creation in hen ospreys. Subsequently the eggs broke during incubation. Ospreys nearly disappeared from many historic nesting areas.
Ospreys never reached official endangered species status, but federal protection as a migratory bird; public appreciation of raptors, and a cleaner environment have all allowed them to stage a dramatic comeback.
Ospreys typically nest in dead treetops near lakes, wetlands, and beaver ponds.
They are also demonstrating a remarkable ability to use novel sites for their nests: atop floodlight poles at athletic fields, transmission tower poles, microwave towers, and even old windmills.
Ospreys build bulky stick nests with a lining of softer mosses and tree bark that can weigh up to 1,000 pounds. These nests provide a bed for the clutch of about three eggs. The eggs are about 2.3 long and 1.8 inches wide, and hatch after 37 to 38 days.
The chicks fledge from the nest 50 to 55 days after hatching.
Home sweet – odd - home
The first statewide survey of nesting ospreys was completed in 2004. The DNR’s Nongame Wildlife Program, Audubon Minnesota and Three Rivers Park District were primarily involved, natural resource professionals from state and federal agencies and numerous citizens reported osprey nests.
A total of 608 active osprey nests were reported. Reports came from 30 counties with Crow Wing County having the highest number - 107 nests.
The 2004 osprey survey revealed that this bird is currently using a wide variety of nesting structures.
In the metro counties, most ospreys nest on platforms designed specifically for ospreys.
In the Brainerd lakes area, some dead trees are used, but many nests were found on power line poles and several were on communication towers.
Further north, dead trees are the most common nesting sites, while in northeastern Minnesota, a number of nests were in live trees.
Ospreys also used a variety of unusual nesting sites; floodlight poles over athletic fields, an old windmill, a rolling stairway, a water tower, a river marker buoy, and the scaffolding of a pumping barge.
When compared to recent historical locations of nest sites, ospreys have expanded their nesting range in west central Minnesota and in the metro counties.
They have not yet reestablished nesting activities in southwestern Minnesota where they once nested along the Des Moines River.
DNR public information officer Kristi Coughlon and Herwig provided information for this article.