DISCOVERY FILE: Osprey
By NASA [Public domain], via Wikimedia Commons
Biology and Migration
Ospreys are large black and white fish-eating raptors. Their average length is abouttwo feet and their wingspan is between 58 and 72 inches, or around five to six feet. Adult ospreys weigh between 2 and 2 ½ pounds. They can live 15 to 20 years in the wild.When flying, Ospreys hold their wings back in an “M” shape.
Ospreys eat almost entirely fresh-caught fish.When ospreys hunt, they hover 30 to 50 feet over water near shore, looking beneath the surface for fish. Once they spot their prey, they dive feet first to catch fish. If successful in grabbing a fish, they carry the fish with its head pointed in front. This helps the osprey to fly easier.
In Connecticut, Ospreys live mostly along the coast. They build nests usually at the end of March. Often the male finds the site before the female arrives. Nest building continues through the middle of April.
Ospreys nest in tree tops, poles, towers, sometimes roof tops, chimneys, navigation buoys, rock pinnacles, stick piles, and even on the ground. They never build nests far from water. Materials include sticks, grass, seaweed and mud.
Ospreys begin their long journey south for the winter starting in September.The ospreys that nest inConnecticut migrate to spend the winter along the Gulf of Mexico, the Caribbean,as well as Central and South America. Parents don’t teach their young where to go, because they migrate first.
Environmental Science – Global Changes
About fifty years ago,ospreys were almost wiped out because of the use of DDT -- a poison that was sprayed on crops to kill insects. This poison became concentrated in the bodies of ospreys. Scientists discovered that DDT prevented birds’ eggshells from forming properly and hardening.Many of the eggs would break when the mother birds sat to incubate them, so their offspring never hatched. Numbers of ospreys declined at an alarming rate. Partly because of a famous scientist and writer named Rachel Carson, DDT was banned from being sprayed on crops to kill insects.
Wildlife biologists have been concerned that Ospreys getother poisons in their tissues. High levels of mercury have been found inOspreys. Mercury cause many health problems in animals.Other problems for Ospreys include getting caught in rope in the nest and not having dead trees to nest in. People have removed tall trees that Ospreys chose for their large nests. Recent storms have brought down many of the remaining trees.
Conservation – How to Help
Conservationists have helped Ospreys by building nesting platforms. Partly because of this, Osprey populations have grown.There are many organizations whoteach the public about Ospreys. By protecting marshes and keeping beaches unspoiled, Ospreys will do better.
Resources
Here is a link to the real time “Osprey Cam” at Milford Point in Connecticut. Ospreys can be seen in the nest in the spring and summer.
Websites
(reading level is higher than grade 4, but there are a lot of good photos and information here)