Welcome to Leavenworth Virtual Spring Bird Fest week with me as your volunteer guide along the Columbia or Wenatchee Rivers. Osprey are large fish-eating bird-of-prey found not just in Wenatchee, but all around the world. Today’s blog serves to introduce this species, using spectacular shots by local photographer, Frank Cone. Take a walk on the Apple Capital Loop Trail this week, and you’re sure to see an osprey, either on the wing or on a nest. In mid-April, osprey began arriving to where they were born in the Wenatchee Valley, commuting from winter coastal habitats in western Mexico and Central America.
Pairs form at the nesting site, with males arriving before females. Males bring most of the stick material to build the nest, and the female does the arranging. This furniture re-arranging continues for months and even the chicks get a hand in changing the nest to a flatter shape over time.
Osprey have long wings, and typically fly with a “bent elbow.” Their “rowing” pattern of flying is steady and shallow. Looking up, their heads appear to be small and the tail is medium in length and rounded at the tip. The breast and belly are mostly white.
Their backs and upper wing coverings are chocolate brown. A dark line goes through the eye and the bill is strongly hooked. These features help you to rule out other common birds-of-prey that use the same habitat, like bald eagles, turkey vultures, or hawks.
Osprey have long legs and large feet. The un-feathered parts are covered in rough scales all the way down to the end of the toes. Scales on the foot bottoms have sharp points that securely hold a slippery fish. The outer toes can swivel to point forward or backward to help the bird keep a grasp on a wiggling slippery fish. Check out the long curved talons. This is quite a tool-box for fishing!
Osprey dive feet-first and are limited to a water depth of about 3 feet. They have keen eyesight and look for fish while hovering about the water (from 30-130 feet). When a fish is spotted, the bird plummets and extends it legs forward just before plunging the feet into the water. The bird is partially immersed in the water and uses its powerful wings to lift up, carrying 10-50% of its body weight in fish. Many species of fish including trout, salmon, northern pikeminnow, and suckers form a large part of their diets.
Once airborne, the osprey maneuvers his feet to aim the streamlined body of the fish facing forward, reducing drag. The fish is taken to a high perch, often near the nest, where it is eaten. Osprey don’t store or cache food, so uneaten parts are discarded.
Males deliver food to females beginning at courtship, often with the female making a begging call. Females continue to depend upon their mate for food from egg-laying until the young are able to take food themselves from the male.
Typically, the male will bring food to a near-by perch or to the nest, eat the head and top part of the fish, then present the rest to the female. She will pick it apart and feed small bits to the young, eating the tail and tougher parts herself.
Females sit on (brood) the eggs for about 40 days, and then continue to brood the young hatchings for two weeks. Hatched chicks take up to 43 days before they fly from the nest. 83 days is a long time for the female to “Stay-At-Home,” which has new meaning to all us during the Cornovirus pandemic.
Soon after the young are fledged, the female departs for wintering grounds, handing over all parental responsibilities to her mate. For the next 1-2 months, the male continues to bring food to the young birds, while they begin to learn how to fish. In the early fall, the family separates with each bird migrating south independently. The juveniles migrate south on their own, and then spend the next 18 months on the wintering grounds. In the spring before turning two, each young bird begins the cycle again, flying north from the subtopics.
Between 1950-1980, Many regions had steep declines of both osprey and bald eagles due to high levels of contaminants (especially DDT) in eggs, that resulted in eggshell thinning and poor hatching success. Osprey studies were used as important evidence in court cases that blocked the use of persistent pesticides. Since then, osprey populations have grown rapidly and their range has expanded world-wide.
Osprey have adapted to our human-built environment as they readily use artificial nest platforms and they tolerate human activity near their nests. Current human-caused threats include entanglement in fishing nets or in plastic baling twine sometimes worked into a nest. Collsions with vehicles is a leading cause of fatality for osprey.
The U.S. Migratory Bird Treaty Act protects osprey and eagles, and utility companies have engineered clever solutions to minimize death due to electrocution when birds perch on power lines.
In our area, Chelan PUD has strategically erected artificial nest platforms near power poles, to minimize potential injury or death by creating more desirable nesting sites away from danger. Great blue heron, Canada Goose, great-horned owls and bald eagles are resident birds that sometimes occupy an osprey nest prior to their arrival and disrupts the breeding cycle for an osprey pair.
Students wanting to learn more about osprey can start with the Cornell Lab’s Bird Species Guide with more details at All About Birds. Watch live-streaming of the University of Montana’s “Hellgate Ospreys” where Iris laid her second egg on May 8, 2020. Visit the Montana Osprey Project website. Washington State University’s Raptor Club website includes bios of their resident birds (so many cute owls!) and has good information about what to do if you find an injured bird. The University of Minnesota’s Raptors of North American includes facts for all birds-of-prey. Easiest of all, take a neighborhood walk with your eyes skyward to conduct your own field studies of this world-expert fishing bird.
Frank Cone artfully captures avian subjects along Wenatchee’s riverbanks. Most of these photos were taken around Wenatchee in the last two years, at the boat launch at Pybus Market, Confluence State Park, Sleepy Hollow bridge, or at Porter’s Pond in East Wenatchee. Frank is a lifelong resident of the Wenatchee Valley. He has held a variety of jobs from Humane Officer to working for Chelan County in the Planning Department. He started pursuing photography approximately 15 years ago. He enjoys all aspects of photography, mainly focusing on birds and macro work. Visit his Flickr websiter especially to see his great blue heron and bald eagle images.
Wonderful pictures of the osprey!