Blog #478 Shhh! Do Not Disturb
Both male and female Ospreys defend their nests if disturbed to ensure the survival of their eggs and chicks. At the Salt Point Natural Area and elsewhere around Cayuga Lake, breeding Ospreys can be observed chasing avian intruders away from their nests, often in dramatic chases. If you have been watching the Salt Point Osprey Nest Cam 2025 Live you may have seen homeless Osprey intruders flying by the nest to the consternation of Ursula and Orpheus.
Unmated intruders, both young and old, who have not found nesting sites and mates for a variety of reasons and are looking for openings in existing sites. They fly about the colony, inspecting the nests for lost mates and harassing nests with weak, older birds hoping to displace them in a fight. Ophelia, Orpheus’s faithful mate of ten years and mother of 27 of his fledglings, was replaced in 2022. Ophelia arrived at her nest four days after Orpheus and was met by a young female intruder, Ursula, who by then had mated numerous times with Orpheus and was fully established in the nest.
Ophelia chasing an intruder from the nest, courtesy of Cindy Sedlacek.
Ophelia did not leave quietly. While Orpheus sat on the sidelines in a nearby tree, Ophelia and Ursula duked it out. Hitting with their wings and kicking, they squabbled over ownership of the nest and Orpheus’s favors. These high-tension bouts lasted only a few minutes but were very loud and physical. After one series of aerial chases Ophelia took possession of the nest by pushing, shoving, and biting Ursula’s neck to repel her. Shortly afterwards, Ursula countered her attack.
The females had intermittent shoving matches in the nest and chases in the sky for four days, fighting hard physically and vocally, but Ursula retained control of the nest and slept in it at night as resident females do. Importantly, Orpheus only feed Ursula during this test of wills forcing Ophelia to fish for herself. Without any fanfare or shrieking, the embattled Ophelia, who was probably 11 years older than the young intruding female, disappeared during the afternoon of the fourth day and was never seen again. It was now Ursula's nest.
Now it is Ursula's job to defend the nest. When intruders get too close to the nest, Ursula emits a high-pitched territorial ‘chirping’ alarm call, and mantles (covers) the nest with her body and wings partially extended to shield the eggs. Warning cries—repeating
While the female is primarily responsible for incubation and nest defense, the male will also defend against intruders, especially during courting and breeding, to prevent intruders from mating with their partners. Intrusions and the resulting nest defense can cause dramatic aerial displays above the nest and over the lake with high-speed chases, collisions, and precision hovering or circling to further deter intruders.
Breeding pairs are especially nervous and easily upset by anything entering the nest territory. If a parent leaves the nest unguarded to chase an intruder, the eggs or nestlings are exposed to the cold (hypothermia) or predation by crows and ravens (Corvids). Corvids are such dangerous and common nest pests that Ospreys quickly chase them.
In addition to intruders disturbing their breeding, Ospreys also must contend with threats from Great Blue Herons, Bald Eagles, and Great Horned Owls who predate Osprey eggs and young. Great Horned Owls will even carry off brooding females if surprised at night. Ursula and her sisters are sworn to protect their nest contents and will use their full gamut of defenses to protect their nest and young. However, when accumulated disturbances become too much for a breeding pair, they do not breed that season.
Construction removed several Osprey nesting trees, courtesy of California Builder & Engineer.
To minimize the consequences of nest disturbances, Ospreys tag-team brooding. As soon as one leaves the nest, its mate will take over brooding. Communication between a mated pair becomes more efficient over the years improving the care of the young through their experience. If the nest has too many intruders and outside disturbances during this sensitive period, wasting the birds’ time and energy defending instead of breeding, the birds will simply not breed. Constant disturbances or predation over several successive years may cause a pair to abandon their nest and go elsewhere.
In 2019, an enormous number of disturbances by intruders (sometimes 12 attacks a day) caused Orpheus and Ophelia to switch nests and lay eggs in the Salmon Creek nest. Disturbances at both nests continued, triggering Orpheus to defend the Salt Point nest from intruders although he still fed Ophelia. A confused Ophelia split her allegiances guarding both nests. The unattended eggs were lost to a wile chipmunk, and the year was breeding failure.
By far, the biggest threat to Ospreys is humans, and unfortunately, this pressure is continuous, rather than seasonal. Ospreys are killed and suffer habitat and food supply degradation in both their North and South American homes. They migrate in Spring and Fall from one set of threats to another. Forthcoming blogs will explore this competition between humans and birds.
Kayakers harassing an Osprey nest during the breeding season in Staten Island, NY, by Flicker.
Ospreys are highly adaptable and comfortable nesting among humans, if the humans don’t get too close. Their protective natures cause them to defend against humans if pressured. Putting a ladder up to peak in an Osprey nest, for example, is particularly dangerous as the birds will attack violently with their sharp talons and beaks.
Ospreys living in rural areas generally have less contact with people than those living in urban settings and are therefore most leery of them. Those living in the dense northern forests of Finland have the least human contact and tend to be intolerant of humans, flying off the nest if observers are within 500 yards. Those birds living in towns and parks, such as the pairs nesting in Ithaca’s Stewart Park or Lansing’s Salt Point Natural Area, are acclimated (attenuated) to humans walking by, dogs urinating on their poles, and unruly children below the nests. Ospreys breeding in public places such as Ithaca’s Union Fields are unfazed by a baseball game below. An Osprey’s reaction to human disturbance is individualized; each bird has its own familiarity, experience, and acceptance of humans and must be approached with this in mind.
To protect nervous Ospreys and their offspring, researchers suggest maintaining a 300–500-yard buffer zone around active nests during the breeding season, and 80 yard-radius around inactive nests as they might be reused. For closer looks inside nests turn to nest cameras such as the Salt Point Osprey Nest Cam 2025 Live.
Eyes to the sky!
Candace
Candace E. Cornell
Salt Point Natural Area
Cayuga Lake Osprey Network
Guest photographer: Ithaca’s Cynthia Sedlacek brilliantly captures the Ospreys of Cayuga Lake with the intimacy of a true bird lover. Enamored by the animal’s gorgeous wings and graceful flight, her work is a tribute to the power and grace of these stunning raptors and symbols of environmental rebirth.
EYES ON OSPREYS
WATCH!
Salt Point Osprey Cam 2025 LIVE! authenticated
Salt Point Osprey Nest Cam 2019-23
READ!
VISIT!
Cayuga Lake Osprey Trail Nests Driving Tour
Complete Cayuga Lake Osprey Trail
HELP PROTECT OSPREYS:
• Stay 100-300 feet away from Osprey nests during the breeding season.
If the Osprey vocalizes or flies off the nest you are too close!
BACK OFF IMMEDIATELY.
• Always carry binoculars to view wildlife from afar.
• Collect and dispose of used fishing lines, twine, nets, and plastics
which can kill Ospreys and other animals of the lakeshore
FIND AN INJURED ANIMAL?
Call the Swanson Center at 607-253-3060.
The Janet L. Swanson Wildlife Health Center, an annex of the Cornell University Hospital for Animals, is a veterinary hospital dedicated solely to the treatment of ill or injured native wild animals. They provide expert medical and surgical care for over 1,000 patients annually, from locally and across the state of New York, with the goal of releasing them back to the wild. The Wildlife Health Center operates within Cornell University, a registered nonprofit, and relies largely on public donations.
Please donate to keep these doors open.
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