Nearly wiped out in southern Michigan at one time, osprey (Pandion haliaetus) are now recovering within the state due in large part to the concentrated efforts of the Michigan Department of Natural Resources (DNR), Huron Clinton Metroparks, Detroit Zoological Society (DZS), DTE Energy and more than 100 volunteers.
The use of DDT and other pesticides, which caused the thinning of the birds’ eggshells, caused osprey populations to decline. Once commonplace in the Great Lakes region, osprey became mostly a bird of remote northern lakes and ponds. After the use of DDT was banned and the osprey population became more productive, state wildlife officials seized the opportunity to re-establish ospreys. In 1998, the DNR initiated a program of relocating or “hacking” the raptors to southern Michigan. The program, which was supported by donations to Michigan’s Nongame Wildlife Fund, removed chicks from active nests in northern Michigan and placed them in parks around southern Michigan. The movement of ospreys occurred over a span of 10 years. In 2012, the DNR identified at least 49 active nests in southern Michigan – a substantial increase from the one active nest reported in 1999.
“This is a true wildlife success story,” said Julie Oakes, DNR wildlife biologist. “Each year we have new nests, and we have already exceeded our original goal of 30 active nests by 2020. We have been able to remove osprey from the threatened species list and restore their numbers in Michigan.”
During reintroduction efforts, DNR staffers removed male osprey chicks from their nests and placed them in hacking boxes, where they were fed and cared for daily by volunteers. A male will build a nest close to the location where he learned to fly, and the female chooses her mate based on the quality of his nest. Once paired, ospreys typically maintain their partner for life. Reintroduction efforts have been so successful that the DNR is no longer planning future hacking activities. However, banding of the chicks will continue each year. A federal bird identification band is placed on one leg as part of a national effort to monitor birds. A second, colored band is placed on the other leg to indicate the osprey’s birth year.
This labor-intensive monitoring effort is a cooperative venture conducted by the DNR, Huron Clinton Metroparks, DZS and staff from the cell phone tower companies American Tower Corporation, Verizon Wireless, McFarlin Tower, Skyline Services, LLC, Earthcom, Hydaker-Wheatlake Inc, and Clearlink Wireless Solutions. Since osprey often nest on cell phone towers, the tower companies have volunteered staff time to climb the towers and lower the chicks to the ground safely in special buckets. The DNR, Huron Clinton Metroparks and DZS staff then proceed with banding and measuring the chicks and collecting biological data before they are returned to the nest. Cell tower companies have cooperated with the DNR by not only reporting nests, but also agreeing to schedule maintenance work around the active season so as not to disturb the nesting pair and their chicks.
“Each year we are seeing osprey from previous years return and nest,” Oakes said. “The hard work of so many organizations is really paying off, and by continuing our extensive monitoring efforts we will ensure that the osprey population remains strong and healthy.”
Images courtesy of the Michigan Department of Natural Resources