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Friday, August 17, 2012

The Osprey Files: Growing Up (Part I)

I've had an amazing time this summer following two nests of Osprey chicks from hatching to flight. While several other nests in the area failed, a pair at Robinhood Cove and another at Wolfe Neck Woods State Park successfully raised 6 young between them. Another generation of Osprey takes to the Maine skies.

I began watching several nest sites back in April and visited them about once every 7 - 10 days through the season. I have to admit that every time I returned to check out the latest activities, I was half-afraid I'd find another failed nest or a hatchling had died.

Sometimes that did happen. Maine had several severe storms early this summer that wiped out a number of nests along the coast. A few other nests were abandoned for unknown causes during the incubation and early hatchling period. Causes of nest failure can include storms, nest instability or destruction, loss of one of the adults, inexperienced adults, disease, pesticides, predation, and many more. It's sad for me when that happens because I'm a softie and form a bit of an attachment to the parents after spending hours and hours observing them.

Shading the younger chicks from the sun on a hot day.

I was happy to find that each time I visited the Robinhood Cove and Wolfe Neck Woods nest I saw bigger, healthier chicks and parents busy with fishing and feeding their young.

The nesting adults at Wolfe's Neck State Park welcomed their first hatchling the last week in May. Two days later the second hatched, followed by a third in another 2 days. The chicks in the Robinhood Cove nest began hatching out about a week later.

Osprey eggs are about the size of a chicken egg and when the young hatch out, the chicks are smaller than the size of a human fist. They're covered with downy feathers and are so weak that they can't easily move around the nest. In an amazing feat of growth, over the course of a short 7-9 weeks the chicks grow an enormous amount, reaching almost adult size (about 22 inches from beak to tail and weight of about 3.5 to 4 pounds). The extent of growth I saw in the chicks between my weekly visits truly astounded me - a huge amount of fish must have been needed to fuel the production of all of those muscles and feathers and talons!

Bringing dinner back to the nest.

Unfortunately because both nests that I watched were much higher than my observation points, I had no way of viewing the chicks when they were very young (The photos I've included in this post are of the chicks at about 3-4 weeks old). At the bottom of this post I've added links to some Osprey cams and nest photos to give you a better idea of what the chicks look like at hatching.

Daily life with hatchlings was something like this:

1) Family wakes up (as early as 4:30 AM here in Maine)
2) "Mom" calls to "Dad" until he flies off to catch food
3) Dad brings fish back
4) Mom eats a little fish and gently feeds rest to the hatchlings
5) Hatchlings snooze

Repeat several times throughout the day, interspersed with fending off intruders, more napping, and shading chicks from the sun/wind/rain/cold/heat.

Division of labor with Osprey was pretty clear with these two pair. Mom controlled goings-on within the nest, staying with the chicks nearly 100% of the time. She closely monitored the young and called out to her mate when it was time to catch another fish. He'd fly off and from 5 to 30 minutes later return with a fish and hand it off to her. She'd use her talons to hold the fish down while her beak tore pieces off so that she could gently feed each chick. She also sheltered chicks from the sun and weather, monitored for intruders, and kept the nest in order.

Dad did the bulk of the fishing and running off of intruders. The males seemed to be "on call," responding quickly to Mom's cries for fish or winging off to drive off a potential threat. He also gathered nest material throughout the season - it seemed like these two nests were always under construction!

Fishing appeared to be good for these two families this year so I didn't see chicks in either nest getting shorted their share. The fish seemed plentiful all of the chicks looked healthy and well-fed.

To be continued...

All text and photos copyright Nancy Rynes, 2012. You may share a link to this blog

Osprey Cam Photos of babies:

Osprey Cam in Montana:

Osprey Cam in Scotland:

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