Eaglet Names and Gender
Posted by Lisa in Blackwater NWR, Branching, Eagle Cam, Fledging
As we announced on our Eaglet-Naming Contest results page, we now have names for our eaglets. The names are Aquila (Latin for eagle) and Avis (Latin for bird). Aquila is considered a male name and Avis is considered a female name, which works out well because based on the size of our eaglets, we believe we might just have a female and male in the nest.
The eaglets are almost nine weeks old, and fledging can occur as early as ten weeks of age, so our eaglets are almost fully grown, and that’s the time when we can see if one is bigger than the other. The larger eagles in the nest are females, since females are almost one-third bigger than the males. Biologists speculate that the females are larger because they frequently stay at the nest to protect the young, while the males are smaller because they must be agile hunters that bring a lot of the food to their families during nesting season.
Statistics seem to show that there is a better chance that females will be the first-hatched chick, and this year we think our older bird might be the female.
In addition to their size, our eaglets are showing other signs of maturity. For example, we recently saw one of the chicks aggressively move toward a fish that the father eagle brought to the nest. When a female chick is almost fully grown, she can dominate the male adult due to her size. Eventually the father eagle might not even land on the nest — he’ll just drop off the food and let the eaglets fight over it. During such events, we’re likely to see one of the eaglets mantling over the food (see example from 2008). Mantling is when a raptor spreads its wings and body over the food to tell every other creature that the food belongs to them and them alone. Again, these will all be signs that our eaglets are maturing and well on their way to becoming self-sufficient eagles.
But before our chicks are ready for the outside world, they first have to learn to fly. So the next milestone we’ll be looking for in the nest is branching. Branching is when the eaglets begin hopping out onto the branches of their nest tree, where they can practice perching and feeling the wind against their outstretched wings. We have an animated GIF (975KB) from another nest that allows you to see how an eaglet works its way out onto the branch, even though it can’t fly just yet.
In 2006, our Eagle Cam at Blackwater got pushed out of position a couple of times, and the benefit was we got to see some of the branches around the nest where our eaglets could perch. Here in Photo 1 and Photo 2 you can see that the cam nest tree has several large branches available for the eaglets. There is also a branch on the left side of the trunk that has been popular with past eaglets as well.
We would expect our older bird — Avis — to be the first to begin branching. Unfortunately when the eaglets begin to branch, they won’t be as visible in the nest, but at least we’ll know their absence means they’re continuing to develop as healthy eaglets should.
In our next web log entry we’ll have new videos of our eaglets. Thanks again to everyone who entered our contest and also thanks to those who have been sending in photos of our birds for the gallery.
Until next time,
Lisa – webmaster
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Tags:
eagles, wildlife refuge, eagle cam, Blackwater Refuge, Maryland
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