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Encyclopedia Dubuque

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OSPREY

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The osprey is being reintroduced to the Dubuque area.
OSPREY. One of the largest birds of prey in North America and known on all continents except Antarctica. The osprey feeds almost entirely on fish. Identifying characteristics of the bird include its white breast, forehead, and belly with black back and wings. The wingtips are angled slightly backwards. The wingspan is between 59-71 inches. From a height of one hundred feet they can spot a fish under water. They then dive at speeds up to 40 miles per hour into the water for their prey. The osprey is the only raptor with closing nose flaps that allow them to completely submerge.

The population of ospreys declined a great deal between the 1950s and 1970s. Causes for this included pesticide poisoning and eggshell thinning similar to that which affected the EAGLE (BALD). With the ban on the chemical DDT, populations increased rapidly. It is still listed as endangered or threatened especially in inland states where populations were small or wiped out after the pesticide years.

The osprey builds its nest on man-made structures, such as telephone poles, channel markers, duck blinds, and nest platforms.

Osprey eggs do not hatch all at once. The older chick dominates its younger siblings. If there is plenty of food, little aggression is seen among the chicks. If food supply is limited, the younger chicks often starve.

In July 2008 a Dubuque County osprey restoration project was begun. After being examined by veterinarians, four forty-two day-old osprey chicks were placed in a "hack box" near Mud Lake. One osprey was sponsored by students of the Eleanor Roosevelt Middle School Sierra Club. The Web of Life environmental club of the UNIVERSITY OF DUBUQUE raised $2,050 for the project including $1,000 for the box and the balance for two birds, one in 2009 and one in 2010. Other contributors included the Dubuque and national chapters of the Audubon Society. The Dubuque project was the 10th and final one in the Iowa Department of Natural Resources osprey reintroduction programs and the only one on the MISSISSIPPI RIVER.

(Photo credit: Greg Gillson)