Blog #440 Navigating in an Osprey World Part 3

An adult eagle harassing an Osprey with fish, courtesy of Cindy Sedlacek.

A few yards off the lighthouse in Ithaca, a battle between an Osprey and a bald eagle ensued over the ownership of a fish. Although they are excellent hunters, eagles are kleptomaniacs when it comes to Osprey and fish. An eagle is well equipped for fishing with their large deadly talons, but instead of catching its own, the eagle will go after a fish-toting Osprey, forcing the Osprey to drop their prey, which the eagle grabs in midair. It’s good trick if you can pull it off, and the eagle does most, but not all, of the time. When the eagle misses his booty, the fish is often left on the ground for scavengers. As opportunists, eagles also scavenge carrion or catch and eat amphibians, invertebrates, small mammals, reptiles, and other birds’ nestlings.

Bald eagles and Ospreys share the same habitat, often leaving Ospreys the victims of fish and nest raids by the eagles. Once an eagle gets an Osprey in its sights, the eagle can be a spirited foe. A well-known 2016 video* from Audubon Maine showed a brutal if not clever attack by bald eagles on an Osprey nest. At dusk, with both Osprey parents away from the nest, the bald eagles swept in from over the water toward the nest containing three fledglings. One fledgling flew for safety, but it was caught by an eagle. The Osprey parents tried to stop the raid, but they could not match the speed and strength of the eagles, which managed to nab two chicks with their huge talons. It’s not uncommon for Osprey to lose their entire brood to eagle attacks.

Adept at soaring and diving but not as maneuverable as other hawks, Ospreys fly with stiff wingbeats in a steady, rowing motion and vigorously chase birds that encroach on their nests. As underscored in Blogs 438, 439, and 441, Ospreys also launch their share of aggressive attacks: some of them are versus deserving eagles or cormorants and others against geese and ducks who happen to be in the wrong place at the wrong time.

Osprey territories only encompass the airspace around their nests, while eagle territories can range from 2 and ½ square miles to as large as 15 square miles, depending on the availability of food. Both top predators, they share the same watery habitats and eat the same fish, but usually keep to themselves as the two don’t mix. Eagles don’t migrate long distances as Osprey do and are often found sitting in Osprey nests in the off-season. Once the Ospreys arrive in early April, the eagles are back at their nests busy with their nestlings. 

Eagle squatting in Osprey nest; Osprey fights to get it back, courtesy of Mark Faherty. 

 

Numerous eagles and Ospreys nest at the shallow north end of the Cayuga Lake in where fish are abundant and around the wetlands of the Montezuma National Wildlife Refuge (MNWR). Does the bald eagle know it will have more opportunities to steal fish if they nest near Ospreys? Doubtful. Eagles are probably not capable of such advance planning.

How does the presence of bald eagles on Cayuga Lake Basin affect the Osprey population? The bald eagles nest and dominate MNWR. Eagles also nest as far south as Aurora on the east side of the Lake and Ulysses on Maplewood Road on the west side. Eagles are common around the other Finger Lakes where Osprey numbers are low. Instead of keeping to themselves, the eagle pair at Maplewood make a habit of visiting the Osprey nests at the south end of the Lake every morning. Their usual modus operandi is to check out the nests, beginning at the Union Field Ballpark, before flying east over to Stewart Park. Their rounds continue to the Inlet nest past the Cormorants

An immature bald eagle chases an Osprey for its fish, courtesy of Cindy Sedlacek.

nests, and over to the nest near the suspension bridge in the park. After circling the creek and the Fuertes sanctuary, the eagles explore the Youth Bureau nest. 

If any of these nests contain unattended nestlings, the eagles pose a risk, but usually they encounter a screaming female Osprey ready to protect her offspring and nest. Continuing on their reconnaissance run, the eagles circle the shallow water just off Stewart Park looking for an Osprey flying with fish, which the eagle will race toward. If the Osprey does not drop the fish, a fight, talon to talon, often ensues. Typically, the eagle gets the fish, and the Osprey returns to hunting although on rare occasions they fight until injury or death. 

These daily, nerve-wracking scouting runs through the Stewart Park Osprey colony are usually uneventful although they do upset the nest owners. Several years ago, the brood in the Youth Bureau nest disappeared and were presumed stolen by eagles during the day or great-horned owls at night. The eagles’ daily presence riles up the cormorant colony, the great blue herons, and puts the Ospreys on edge. If these early morning raids increase dramatically during the brooding season, they might disrupt the Osprey’s breeding for the year. 

While Ospreys will nest, fish, and live in proximity to people, eagles tend to stay away. The waters off Stewart Park are particularly rich in fish and should be attractive to the eagle, but they rarely fish there. Instead, they wait for a free meal. Since the eagles only appear in the early morning when park attendance is low, perhaps the many park visitors help to repel the eagles later on in the day.

Eyes to the sky!

Candace

Candace E. Cornell 

Friends of Salt Point, Lansing, NY

Cayuga Lake Osprey Network

cec222@gmail.com

 

Guest Photographer:

Cynthia Sedlacek, musician and Director of Data Administration and Reporting at Cornell University, is a surprising artistic talent. Cynthia’s affection and admiration for raptors are evident in her exciting photographs primarily of Ospreys nesting around Cayuga Lake and the red-tailed hawks of the Cornell Campus. Her photographs of local Ospreys are incomparable as she captures their essence, their jizz, and their inner bird. From the hard-to-see nestlings to the fast-flying adults, Cindy goes beyond the pale to catch all aspects of Osprey life in the Cayuga Basin. “My camera allows me to capture their beauty in many ways that the human eye can’t see,” she says, “like their spectacular wing positions and detailed feather patterns.” Cindy and her husband Karel are also avid nest monitors for the Cayuga Lake Osprey Network and video stream footage of the campus hawks.

EYES TO THE SKY!

WATCH!

Salt Point Osprey Nest Cam

out of order

READ!

 On Osprey Time: Ospreys of the Finger Lakes

VISIT!

Cayuga Lake Osprey Trail Nests Driving Tour

Complete Cayuga Lake Osprey Trail

HELP PROTECT OSPREYS:

•Stay 300 feet away from nests during the breeding season. If the Osprey vocalizes, you are too close! Back off Immediately.

•Carry binoculars to view wildlife from afar.

•Help keep local waters clean, healthy, and safe.

•Recycle used fishing lines, twine, and nets, which can kill Osprey.

•Join the Cayuga Osprey Network and volunteer to help monitor Osprey nests: cec222@gmail.com.