March 07, 2006
Chick Competition
Nest Update: The chicks are developing quickly, like little eaglets do. Soon they'll start regulating their own temperature, and they will also develop a second coat of down (woollier and darker), which feathers will eventually replace. Also their large, awkward yellow talons will become more noticeable.
In this photo comparison of the 2006 and 2005 chicks, you can see what is in store for us. Notice that in the 2005 photo, each of the eaglets was in a different stage of development at the time. The woollier down is being replaced with dark feathers on the two oldest chicks, while the youngest still has most of his second coat of down.
Chick Competition
I was at the Visitor Center this weekend and spent some time watching the chicks interact on the live monitor. Our staff and volunteers at the Refuge can watch the monitor throughout the day, and after talking with them and watching some of the video myself, we can say one thing about the oldest -- the chick is a typical firstborn bully.
When watching the two chicks together, you sometimes see the oldest push and peck at the youngest, until the second chick takes a submissive position -- usually lying with its face down in the nest. This isn't a surprising development -- firstborn raptor chicks are known to be bullies, and are driven by instinct to establish themselves as king of the nest. The younger chick learns to act submissively, which earns the youngest a reprieve from harassment, at least for a little while.
Eagle biologists report that sometimes when food is not abundant in a crowded nest (like a three-chick brood), the youngest eaglet could succumb to starvation because the oldest eaglets will make feeding too difficult.
In the Eagle Cam nest, this is not a problem with the two chicks. We have a father eagle that is providing plenty of food, and a mother eagle that does her best to make sure that both chicks get fed at meal time -- whether the oldest chick is happy about it or not.
While watching the mother, it is remarkable to see her efforts to feed the youngest. The youngest knows that it will always eat second, so sometimes its head will be turned away from the mother while the oldest is eating. The mother eagle will tear off a piece of fish and hold it out to the youngest until it turns its head and sees what she is offering. She also holds out food to the youngest even while it's laid out in a submissive posture on the nest. Regardless of the youngest's position, she finds ways to feed it.
Folks at the Refuge did say that the bullying seems to be lessening, and this is common too. As the youngest chick gets bigger, the pecking and pushing will diminish. The chicks might still act aggressive at times, but soon the youngest chick won't be as easy to push around.
Several cam watchers have asked if a parent will ever intervene when chicks are fighting. Most eagle biologists say that it is not common for the parents to intervene. They explain this by saying that either the attacks are so quick that there is nothing the parent can do or that maybe this is the parent's way of making sure the strongest chick survives to carry on the species. Approximately 50% of fledgling eaglets will not survive to breeding age, so it's imperative that the strongest chick is well fed and healthy if it's going to have a solid chance of surviving. It's also possible that chick death is a natural correction in an area where the food supply is just not large enough to support big raptor families.
But does this mean the parent never intervenes? No -- as is usually the case with animals, even when we think we know them, they will often surprise us. In the book The Bald Eagle: Haunts and Habits of a Wilderness Monarch, the Canadian author describes several incidents he witnessed of eagle parents attempting to stop chick violence. He reports that in some nests he saw parents toss grass on feuding chicks, or immediately begin feeding the eaglets to break up the tussle. One parent even pecked a chick on the head when the oldest chick pecked its younger sibling.
But the most interesting story the author mentions is about a younger chick, called C2, that decided he had been harassed enough by his older sister, C1.
"In a flash, little C2 lunged forward and bit C1 on the side of the head. The force of the attack knocked C1 backward into the nest. C2 held on. I could not believe my eyes; C2 was twisting and shaking C1 from side to side. This was no ordinary fight...It wasn't long before C1 began to call out with a high-pitched chittering sound. I had only rarely heard this distress call before. Peck, bite, shake; C2 showed no sign of diminishing his assault."
The author goes on to say that the mother eagle finally bent down and took the littlest chick's beak in hers. By gently rocking back and forth, the mother tried to get the youngest to let go, but it didn't work. Finally the mother sat down on both eaglets and started rocking back and forth to separate them with her body.
A little less than twenty seconds later, C2 was seen peering out from under his mother's breast. But it wasn't until over an hour later, when the male landed on the nest and the female stood, that C1 was seen squatting in the nest, apparently with no permanent damage from her attack.
The author stated that the younger male never tried attacking his big sister again and remained subordinate to her for the remainder of their nest life. But who knows how the attack would have ended if the mother had not intervened.
Gallery
As a reminder -- we updated the Gallery today with many amazing photos, so be sure to check it out. And thanks to everyone who sent in their shots. Even though we don't have room to display them all, we greatly appreciate receiving them as they are a valuable record of the chicks' development.
And for those who missed it, this week we posted a special Bald Eagle Wallpaper for our cam watchers.
Until next time,
Lisa - webmaster
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