Osprey will return ‘home’ to Eastern Iowa

One of the most superbly adapted raptors to call Eastern Iowa home is the osprey.

The osprey has a cosmopolitan distribution, being found on all continents aside Antarctica. In the United States, a sedentary population exists in Florida, while all other osprey are migratory. The Florida subspecies, along with another sedentary population in Australia and Tasmania, are most distinct from the larger, darker-bodied and paler-breasted subspecies that occurs throughout most of the Americas.

Although it is unclear if ospreys ever routinely nest in Iowa, the Eastern Iowa corridor is one of three areas in the state where they were relocated and are having breeding success. The other two places are the Des Moines metropolitan and Spirit Lake areas. One commonality about these areas is they have either large lakes or reservoirs present.

Osprey are more common around estuaries and other features like bays. They are less locally common or even rare around more inland bodies of water.

Look for a large raptor (6-foot wingspan) with a white head, dark mask and brown bill. The mask is thought to reduce glare of water.

Osprey have a light eye. The upperside is dark while the underside is mostly white on the belly. Females can have a dark necklace across the chest. The wings have a dark “wrist” area and dark secondary feathers. A dark upperside offers camouflage on a nest from predators like the great horned opwl. A white underside helps blend an osprey into the sky when hunting above water.

In flight, osprey can be readily identified by behavior. During warmer Iowa months, when water is open, osprey are often seen hovering over bodies of water. They bow their wings upward with a special joint when flying, which is an adaptation to help propel them out of the water.

This bowed wing appearance will differ greatly from the straight, plank-like wings of a bald eagle. During the months after osprey have migrated south, misidentifications occasionally occur with subadult bald eagles.

Another great way to tell an osprey in flight is how they hold their catch. They will position a fish after catching it so the fish aligns in the same direction as their body. This makes carrying the fish more aerodynamically feasible, allowing them to fly several miles away from their nest to catch food.

One of the most memorable things about seeing an osprey is watching them dive for a fish. They can see fish hovering well over 100 feet above the water, then suddenly fall into a dive up to 40 mph. With feet held out in front they burst through the surface of the water, sometimes completely submerging. They are adapted to quickly shedding water and lifting off in a seamless fashion. Other underwater adaptation included closing nostrils and nictitating membranes to protect their eyes.

In the Eastern Iowa corridor, look for osprey to trickle back in late March and then be more detectable in April. Most leave by late October, however some can linger into November, especially if water stays open.

Birds to look for in April

Birding Calendar

Iowa Ornithologists’ Union spring meeting, April 29 through May 1 — Swan Lake State Park, Carroll. Field trips destinations include Dunbar Slough SWMA, Swan Lake SP, Whiterock Conservancy.

The keynote speaker is Ann Lacey and her topic is “Saving the Cranes of North America.”

Less than a century ago, the great naturalist Aldo Leopold noticed declining numbers of sandhill cranes in the wild. He predicted the species would die off in his lifetime. Instead, we are happy to report, cranes have rebounded spectacularly. In fact, the upper Midwest today is host to both the most species and the rarest species of crane in the world.

In Iowa, it isn’t unusual to see sandhill cranes. People have occasionally noticed hundreds of cranes in the sky during migration. The birds are large and their flocks can be immense.

Saving the crane was no accident, though. It has taken decades of work. Lacy, senior manager of North American programs for the International Crane Foundation (ICF), will join us on April 30, at 7 p.m. to share her expertise and wisdom on saving both the sandhill and the whooping crane, along with 13 other species of crane. She also will talk about the behaviors and natural history of cranes here and around the world.

Registration can be found here. I highly recommend attending what will undoubtedly be a phenomenal meeting. Non-IOU members and new birders are encouraged to come.

Brandon Caswell has a keen interest in natural and social sciences. He enjoys bird-watching and nature photography in his spare time. He and his wife live in Marion with their two children.