Tonight Sutton posted a long (!) essay on what they thought might have happened to E1 - with an excursion off into falcon nests. I am copying it here. But if you don't want to read the whole thing, basically they are saying they don't think the eaglet was speared by Mom and that they don't really know what happened in the nest that night.
20 March 2012: As most viewers know, one of the young chicks disappeared over the past weekend from the Sooner Lake nest. I have reviewed the clip showing the adult stepping on the chick (
http://www.youtube.com/watch?v=xc926dOI1fA). Actually, such incidents are not uncommon in raptor nests, and while the adults usually "ball their feet up" around unhatched eggs and around "just hatched" young, as the chicks begin to grow, parents sometimes step on their chicks accidentally with open feet or when focused on threats near the nest. Usually, the sharp talons do not have any impact on the chicks, as the primary contact is between the pads on the bottom of the adults' feet (rather than the talons) and the chick.
I have seen tame, captive adult breeding falcons step on their chicks numerous times, perhaps over one hundred, but have never seen a puncture as a result from such accidental "pressure" treading by a calm falcon. Captive breeding falcons that are wild, on the other hand, can accidentally step on their chicks and do serious damage when trying to protect them from a human intruder. For the falcons, extent of damage can be affected by the substrate beneath the chick that is pressed by the adult's foot. Falcons do not build stick nests as do eagles, but instead scrape out a depression in the dirt where they can lay, incubate, and hatch their eggs. In captivity, their scrape or depression is excavated from about six inches deep of quarter-inch pea gravel. This gravel gives away slightly beneath the chick that finds itself occasionally beneath an adult foot.
The nest lining in an eagle nest serves the same purpose. It pads the incubated eggs from the sticks comprising the nest, and it also pads the chicks that lie beneath the brooding adult. Therefore, the lining helps pad the chick that might be "stepped on" by an adult eagle. The eagles we are observing were not upset and were not protecting their young; instead, they were going about daily life in a calm manner. In my opinion, the eagle chick that was momentarily beneath the eagle's foot suffered no damage. And, it is normal for the adults to reach down and "scoop" the chicks back underneath them by using the adult's beak. The fact is that we really have no idea about the cause of what happened to the deceased chick, and we will probably never know. It is important to refrain from deriving conclusions when we have little or no evidence regarding cause and effect. That is why we need sample sizes with many observations before we can draw conclusions. It is documented that adult birds become better parents with age and experience as evidenced by their increased number of annually fledged young. We are sorry we cannot offer any more definitive answers in this case. We know only that young eagles sometimes die in the nest for a variety of reasons.
Dr. Steve K. Sherrod, Executive Director
