Blog #469 Three Weeks Down /Three More to Go
One week…two weeks… now three-weeks old and time is flying for the Salt Point chicks. Their race against time has reached the midpoint of their phenomenal transformation from newly hatched balls of down to their fully-grown adult forms by day 30. The sooner the young grow and mature, the more time they will have to master flying and fishing skills critical to their survival. Having more time to hone these life skills better prepares the fledglings for their grueling solo autumnal migrations to their new winter homes thousands of miles away in South America.
Incredibly, the nestlings' growth is visible day after day as their adult feathers emerge and the birds gain muscle strength and coordination. The three nestlings–O’Connor, O’Leary, O’Shea–are imprinting and forming critical attachments with their parents and learning the finer points of being an Osprey.
Food demands are highest during this period of rapid growth (day 20 to 30 days old) keeping Orpheus busy. During the hotter summer months, Orpheus tends to fish from daybreak until noon. His frequency lets up a bit until late afternoon when he resumes fishing again. Today for example was 80º and humid, with periodic high winds and rain. Orpheus caught and delivered four 4” to 8” fish to the nest from 6:30 am-noon, averaging 8 minutes per catch.
Mother and two 3+week old fledges, courtesy BBC.
Another milestone, wing-flapping, begins in the third week as the nestlings struggle to gain muscle mass, strength, and coordination. Discovering the use of their wings for balance helps while walking in the nest. From day 15 to 30 days old, the nestlings gain about 0.09 lb. each day or 2%-3% of their final weight. During this period of intense growth, their bodies increase in mass and their feathers sprout, but their coordination lags behind. Halfway to fledging means that in 3 more weeks, the nestlings will be ready to learn to fly.
Sleeping most of the day, the chicks spring to life whenever Orpheus brings a fish to the nest. The nestlings use their wings for balance and rock forward on them to get a good stretch. They waddle around the nest with their enormous feet, defecating over the nest edge, and peering over the rim at the people below. When it’s mealtime, the eager chicks waddle over to Ursula to feed. The eldest, most aggressive nestling, O’Connor, weighs almost one pound, half the weight of an adult male Osprey and a fourth of an adult female, which weigh up to 4.4 lb.
Mealtimes can be frenzied, but Ursula maintains order by apportioning the fish so that all are fed. O’Connor, the largest and most aggressive nestling, gapes wide before the others and is first. When O’Connor is satiated with a bulging crop, the smaller siblings get to feed. Ursula usually eats last, consuming whatever is leftover such as the fins, spines, scales, and other indigestible materials. Like owls, other hawks, and eagles, Ospreys periodically expel or “cast” pellets of these inedible parts.
Orpheus eating the head of a forked-tail fish, courtesy of Christine Bogdanowicz.
After catching a fish, Orpheus take it to a tree where he consumes the high-energy, lipid filled lips and head and gives the rest to his family, or he brings the fish whole to the nest. It takes him about 10-20 minutes to eat his fill before giving the remainder to Ursula.
At three weeks old, adult feathers begin to unfurl from the developing “pin” feather tracks covering the nestlings’ bodies. Emerging from blood-filled quills, the feathers push out of their sheaths and the quills flake off. Golden rust-colored feathers adorn their head and nape, and cocoa brown and white feathers cover their bodies and tail. The last feathers to come in are the workhorses responsible for flight—the primary and secondary flight feathers on the wings and the rectrices on the tail. These large, sturdy feathers are the longest and slowest feathers to grow.
Evidently a very itchy process, and the hatchlings start scratching and preening as soon as their feathers begin to push out of their sheaths. Once the feathers are free and open, the hatchlings push, brush, and run their beaks through the barbs to keep them aligned and in good shape. Preening is an essential daily chore for all Ospreys, even the very young. The birds spend a great deal of time preening their feathers, keeping them in good shape, and maintaining a protective waterproofing layer of uropygial oil or preen oil.
The uropygial gland also produces antibacterial and antifungal components, which help maintain the integrity of the Osprey’s skin. The uropygial gland empties to the skin surface through a nipplelike pore at the base of the tail. Ospreys preen by rubbing their bill and head over the preen gland pore and then rubbing the accumulated oil over the feathers of their body, wings and skin of the legs and feet. The oily, waxy substance helps waterproof feathers and keep them flexible.
Eyes to the sky!
Candace
Candace E. Cornell
Salt Point Natural Area
Cayuga Lake Osprey Network
Guest photographer:
Ithaca’s Cindy Sedlacek brilliantly depicts 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.
EYES ON OSPREYS
WATCH!
Salt Point Osprey Cam 2024 LIVE!
Salt Point Osprey Nest Cam 2019-23
READ!
On Osprey Time: a blog about all things Osprey
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.
• Carry binoculars to view wildlife from afar.
• Dispose of used fishing lines, twine, nets, and plastics which
can kill Ospreys and other animals of the lakeshore.
• Become a nest monitor for the Cayuga Osprey Network: cec222@gmail.com.
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