© John A. DiGiorgio, Photographer
OBSERVATIONS AND ANNOUNCEMENT
In 2009 the Delaware Valley Eagle Alliance announced the successful fledging of 4-bald eagle chicks from a nest along the Delaware River in Northampton County, PA.
Directors, John and Yoke DiGiorgio recorded their observations and documented through photography and documentary film, starting the first week in April 2009. The 1st chick was observed that first week in April. The 4th chick was observed and documented on April 27, 2009. PA Game Commission was notified and provided with documentary film confirming the historic event.
Clutch size in bald eagles generally varies between 1 and 3, with 2 being the most common. Reports in the literature of 4-egg clutches are very rare, with some suggesting that they result from two females laying eggs in the same nest. In 1986 on the Chesapeake Bay, a 4-egg clutch was successful with no sign of an extra female. An account was never published.
John DiGiorgio stated, “Based on when we first observed the appearance of each of the chicks, we estimated that there was a one and a half to two week age difference between the oldest chick and the youngest chick. Chick #1 was visibly larger and more developed than the younger three and chick #4 was visibly smaller and less developed than the older three. This remained the case up until they fledged.”
Feeding this 4-chick brood was a time consuming activity and involved both adults. DiGiorgio recalls filming on a particular evening in May where, “Over a two and a half hour time span, the adults brought in a total of five fish and fed the chicks continuously. The chicks formed a semi circle around the adult and were each fed a small portion of the fish at a time. The adult would then move to the next chick, and the next, and the next and return to the first to start again. The adults did not appear to favor one chick over another. All were fed, even the youngest. Very little aggressive behavior between the chicks was observed prior to fledging, even during feeding.”
In total, 14-weeks of footage were captured, from the time that the 4 chicks were first observed through several weeks after they fledged (first flight). Fledging occurred during the 3rd week in June with chick #1 fledgling first, chicks #2 and #3 fledgling two days later and finally chick #4 three days after that.
POSTER PAPER PRESENTED AT RAPTOR RESEARCH CONFERENCE
In 2010, the DiGiorgios collaborated with Dr Bryan Watts, Center for Conservation Biology, College of William and Mary & Virginia Commonwealth University, co-authored and presented a Poster Paper at annual Raptor Research Foundation Conference in Fort Collins, CO to the biologists attending the conference.
The Raptor Research Foundation is a non-profit scientific society whose primary goal is the accumulation and dissemination of scientific information about raptors (hawks, eagles, falcons and owls). This information is used to inform the public (both scientific and lay) about the role of raptors in nature, and to promote the conservation of raptors whose populations are threatened by human activities. Membership includes academic researchers, government agency employees, and others interested in birds of prey. The Raptor Research Foundation achieves its goals primarily through publication of research reports in The Journal of Raptor Research, and through its annual meeting held in a different North American location each year at which research results are presented.
Click Here For Copy Of Poster Paper Presented (PDF)
PROJECT: 4-Chick Bald Eagle Brood Project
PROGRAMS, PROJECTS, EVENTS
© Yoke B. DiGiorgio, Photographer
© John A. DiGiorgio, Photographer
THE DELAWARE VALLEY
Working toward the conservation of
our wildlife and natural resources
6:32 minute documentary
( Compliments of www.naturesartproductions.com )