Blog #447 Growing Like Weeds

June 29, 2023

Ursula mother feeding her 4.5-week-old offspring, courtesy of Cynthia Sedlacek.

Four and a half weeks into the nestling period, the three chicks are almost adult size with the two oldest weighing just shy of a pound each. Full-grown adult males usually weigh 2 pounds, and females can be up to 4.4 pounds. Sleeping through most of the day and all night, the pile of chicks springs to life whenever their father, Orpheus, brings a fish to the nest. When awake, the nestlings waddle around the nest with their enormous feet, backing up to the rim to relieve themselves, and peering over the rim at the people below. They use their wings for balance and rock forward on them to get a good stretch. When it’s mealtime, the eager chicks make their way across the nest to get fed by their mother Ursula.

Once their crops—their storage organs—are full of food, they find a place to snooze, usually in the shade of the greenery that has sprouted at the nest. This is Ursula’s second brood (at this nest), and she is being an attentive mother. She flies around the nest for a minute or so to stretch, but quickly returns to her chicks. Ursula spends up to 9 hours a day creating shade for her offspring by holding her wings partly open or covering the chicks from the rain. Osprey observers call this remarkable behavior the “mombrella” pose.

Offering shade by holding her wings in a “Mombrella” pose, courtesy of Cindy Sedlacek.

Orpheus, the father, is in charge of hunting to feed the family from the beginning of the breeding season until the fledglings migrate. After catching a fish, Orpheus either delivers it whole to the nest or takes his share—usually the head. Ursula takes the fish from Orpheus, usually with some effort, rips off pieces of flesh, and gently feeds it to her offspring. Orpheus is also keen on feeding the chicks and regularly steps in. In another half week, when the chicks approach five weeks old, they will peck at the fish and feed themselves. Ursula usually consumes whatever is left such as the fins, spines, scales, and other indigestible materials. Like owls, other hawks, and eagles, Ospreys periodically regurgitate or “cast” pellets of these inedible parts.

Adult male bringing a fish to the nest, courtesy of Cynthia Sedlacek.

Raising baby birds from hatching to migration is hard work for both Osprey mates. It is especially energetically stressful for Orpheus who has to catch enough fish for five hungry mouths. During the hotter summer months, Orpheus tends to fish from daybreak until noon. His frequency lets up a bit until late afternoon when dinner begins. Today for example was 84º and humid. Orpheus caught and delivered an impressive six 9–12 inch fish before noon taking an average of 7 minutes to catch each fish. Ospreys get most of their water from the fish they eat. On hot days, Ursula and Orpheus will take baths and drink water from the lake and Salmon Creek. Ursula will probably lose about 10% of her body mass from the start to the end of the breeding season. Orpheus will lose less body mass since he can eat whenever he wants.

All birds spend a great deal of time preening their feathers, which keeps the feathers in good shape and spreads protective uropygial oils on them to maintain them. At three weeks, the nestlings begin to get their first set of adult feathers unfurling from the pin (developing) feather tracks. The hatchlings start preening as their feathers begin to push out of their sheaths, which is presumably a very itchy process. The Nest Cam confirms that once the feathers are out of their sheaths and open, the hatchlings spend a lot of time pushing, brushing, and running their beaks through them to keep them in good shape in preparation for flight.

Eyes to the sky!

Candace

Candace E. Cornell

Friends of Salt Point, Lansing, NY

Cayuga Lake Osprey Network

cec22@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.