Make Way for Nestlings

Our story thus far:  The female Bald Eagle has laid two eggs this season, on 2/16-17 and 2/20. Hatching of first egg on Friday, 3/27. You can view the nest on streaming video here. Within the next several days,  if all goes well, both of the Duke Farms Bald Eagle eggs should hatch. For an expert assessment of what we might expect next, here is a Q-and-A with Larissa Smith, Wildlife Biologist/Volunteer Manager for Conserve Wildlife Foundation of New Jersey. Larissa has worked for CWFs Bald Eagle Project for 15 years.

Could you describe the first month of the nestlings development, and what to expect? Recently hatched eaglets will have a grayish-white down called natal down, covering their bodies. The eaglets will not need to be fed right away since they have absorbed the yolk before hatching. When the adults feed the chick they will shred of pieces of meat from the prey and coax the eaglet to eat by putting the food in their beak. Feeding sessions will be the best time to see the new eaglet. Young eagles are not able to regulate their own body temperature for a few weeks so a large portion of the time the chick will be under the adult being kept warm brooding.

What's the next stage? Around 10 days of age they will start to get their second coat of down which is a darker, woollier down called thermal down. This coat acts as an insulator and by 15 days the chicks are able to regulate their body temperature themselves. Their yellow feet will look large compared to their bodies. Both their feet and bills grow to adult size first, giving them a slightly awkward appearance until their bodies catch up. They will be moving around the nest more.

Does it make much of a difference how many nestlings there are? The more chicks the more food the adults will need to bring to the nest. If there is an abundant food supply it shouldnt be a problem. There is sibling rivalry between the chicks and sometimes a younger chick wont always survive. The youngest of three Duke Farms chicks in 2009 did survive and is thriving. These are experienced eagle parents, so having just the two chicks this year should be a piece of cake for them.

How serious are external threats? Eagle chicks do have predators -- Great-horned owls, raccoons. Other eagles are also a threat,  and this has been documented on several other eagle cams. The Blackwater Refuge eagle cam in Maryland in 2012 had an intruder eagle attack and kill both two-week old-eaglets.

Got a question or suggestion? E-mail Jim at wrightjamesb@gmail.com

Jim Wright writes The Bird Watcher columnist for The Record and the Herald-News. He is the author of four coffee-table books about wild places, and the deputy marsh warden of the Celery Farm Natural Area in Allendale, N.J.

Earlier this week:  All about hatching the eggs.

Last week: All about the Duke Farms Eagle Cam.

Two weeks ago: The Anatomy of Bald Eagle nests.

Three weeks ago: A Brief History of Bald Eagle Eggs in New Jersey and All About Duke Farms' Bald Eagle Eggs.

Four weeks ago: Bald Eagle basics.