April 03, 2006

Mating

flapNest Update: This week the eaglets will be six weeks old, and we're starting to see more adult-like behavior from them. For example, we're starting to see the eaglets standing a little better and moving around the nest more, as well as tearing off some of their own food.

As for how they look, here are a couple good comparison shots: The first photo compares how they looked right after their birth in late February with how they look now in early April. In the April photo, notice the current differences in their tail feathers -- the youngest is a little behind in tail growth.

And in the second photo we see how the wings of the mother differ from the oldest eaglet's wings, which are getting fuller every day. We would expect the chicks' first flight to occur around 9-13 weeks of age.

On a slightly different topic: We will be starting our chick-naming contest sometime in the next couple weeks. This year, we thought we'd try something a little different in that we're going to post several sets of names and let our cam watchers vote on them. At the time you vote, you will also be able to enter your email address, and then at the end of the contest we will have a random drawing for a prize from our Blackwater Refuge gift store. We'll announce the start of the contest in an upcoming web log.

And finally, we want to share a photo that one of our cam watchers kindly forwarded to us. Florence Keith of Battleboro, North Carolina happened to spot this bald eagle nest and was able to catch a shot with the eagle on it. It's always interesting to see different types of eagle nests up close. Thanks to Florence for sharing this with us!


Mating

It might seem a little late in the season to be talking about eagle mating considering that the two eagle parents now have six-week-old chicks in the nest, but I had the good fortune last week to have an eagle photographer loan me an eagle mating photo.

Gerald McKenna, whose gallery link I posted not long ago, pointed out that he had an eagle mating photo on his site. We've had a few off-angle mating photos in our Eagle Cam gallery, but this photo was special in that it offers such a clear view. Much thanks to Gerald for this unique look at something many eagle lovers never see in the wild.

When talking to people about bald eagles, it's not uncommon to hear the story repeated that bald eagles will mate in the air, with talons locked, as they're free-falling to earth. While it is true that bald eagles will engage in dramatic aerial displays when courting, the real mating or copulation occurs on the nest or in a tree -- not in the air.

As for the bald eagles' aerial displays during courtship, most of them are very impressive. One is called the cartwheel display, where the eagles will fly high, lock talons, and then cartwheel to earth, only breaking apart at the last moment before they hit the ground or water. Another is the chase display, where after chasing each other they will lock talons and roll together. And finally there is the roller-coaster display, where an individual eagle will fly high, fold its wings, then plummet down, only to swoop up at the last minute to avoid hitting the earth. While these aerial activities are certainly captivating to watch, eagle biologists report that the ritual of building the nest together is probably more powerful in securing a tight bond between the pair.

Another point to remember is that not every cartwheel display is courtship behavior. Cartwheeling is also often associated with aggression and defense of a territory. Sometimes eagles will grab at a competitor's talons or even lock talons and plummet to earth with the other bird as a form of battle and intimidation.

On the ARKive wildlife website, they have an interesting video of two European white-tailed eagles (the closest relative to our bald eagle) performing an aerial display. The video gives you a good look at the talon-grabbing and cartwheeling behavior. Go to the site to view or download the video (it's a 5MB download). The downloaded movie plays better.


Until next time,
Lisa - webmaster
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Posted by Webmaster at April 3, 2006 06:54 PM