May 27, 2006
Chicks #3 and #4
Nest Update: The third and fourth chicks each arrived after 36 days of incubation. At this point the first three chicks look healthy and are growing nicely, but we're not sure what will happen with the fourth chick. The youngest was five days behind the oldest and is a good bit smaller than the other three, so we'll just have to wait and see if it can get enough food to survive. We hear from the Refuge staff that they've only known of one other osprey nest that had four chicks at the Refuge, but the fourth didn't survive. So four healthy chicks is a real long shot.
The good news is that our parents seem very capable and have impressed us with their parenting skills. The father osprey has really picked up his meal deliveries, and the mother has been doing a great job of covering and feeding the young. As our cam watchers might remember, from 2001-2004 we had a very capable couple on the cam platform but they moved to another nest last year and we had a younger couple in 2005. The 2005 father osprey was not a good provider, and his performance created tension in the nest between the oldest and youngest chicks. This year, we weren't sure which couple had returned to the cam platform, but after watching this couple in action, we wouldn't be surprised if this was our old couple from 2001-2004.
I wanted to highlight some great photos we've received over the last few days. First, here is a funny shot showing the first three chicks lined up, possibly in their birth order. And as a contrast, here is a photo showing the chicks lined up in a more democratic row for a feeding session. The trick for the fourth chick will be to break into this crowd of bodies and get some food without drawing the ire of a bigger sibling. But that's easier said than done, as we see in this shot from Saturday morning where the fourth chick is not anywhere near the food.
Here is a set of shots that show how a food delivery usually takes place. The father brings in a fish, usually headless (he eats the head) and hands it off to the mother, who then feeds it to the young. Sometimes the father will take back the meal later if the mother did not finish it or if he is still hungry.
I had noticed that the father osprey often sits on the far left corner of the platform. When I asked the folks at the Refuge about it, they reported that there is an eagle that frequently sits in a snag off to the left of the platform. The eagle has not attacked the family, but the father osprey is not happy about the eagle's presence, and so the father likes to sit and glare at him from that corner of the nest. We also hear that the mother osprey occasionally calls out at the eagle as well. Technically, an eagle could take a chick, but it's kind of rare. Still the ospreys do not like a large predator being near their fish or their chicks.
Last year, I happened to be on our Wildlife Drive when a pair of eagles settled into the trees near the osprey platform. I had my video camera and was able to take some short movies of the mother osprey dive-bombing an offending eagle. You can see the videos in our web log archive.
Competition
Last year was the first year of our Osprey Cam where we saw clear signs of aggression and subordination within the nest, and it was clearly due to the father's infrequent meal deliveries; often the mother had to leave the young and go fishing herself. The 2005 nest only had two chicks, but the lack of food made the oldest chick very aggressive toward its sibling, and the youngest had a difficult time in the nest, spending many feedings with his head down in a subordinate posture. We believe this was directly tied to the father's poor fish delivery, because when we had two chicks in the previous years, we never saw this level of subservient behavior in a two-chick nest.
Now in 2006, we have a scenario we have not had before, in that we have four chicks. If the fourth chick can hang on and get some of the meals, then competition might develop between the last two chicks, with the third chick attacking the fourth.
In the fascinating book Return of the Osprey: A Season of Flight and Wonder, author David Gessner writes about an osprey nest he watched in Cape Cod, Massachusetts where the third chick pecked the fourth chick mercilessly, eventually killing it. Not all battles end with a physical murder. Sometimes the bullying chick will keep the youngest chick subordinate to the point that the youngest chick never gets enough food during meal time and then starves to death.
As for our osprey nest, we hear that after both the second and third chicks were born, the mother hesitated a bit before feeding them. But then it seemed she adjusted her feeding chores and managed to get some food to the lesser chicks as well.
Our friend Georgena Terry is a volunteer webmaster at the Friends of the Montezuma Wetlands Complex in New York and is also the founder of Terry Precision Bicycles. She was at the Refuge right after our second chick hatched, and she was able to observe the action on our TV monitor at the Visitor Center. Here are her comments:
"I saw some really neat behavior regarding the first feeding by one of the parents. The newest chick, wobbly though he was, had his head back and beak agape, waiting for his serving. The parent steadfastly fed the older chick, ignoring the younger one until almost all the fish had been devoured. Then she finally offered him a little piece. He took it in his beak, but was unable to get a good grip and fell over sideways, losing the fish and falling into an exhausted heap, but still sniffing about for that lost morsel. By then the feeding was over and the parent gathered the chicks and eggs together, tidied up and took them all under her breast again."
Sometimes a mother osprey seems to "favor" an older chick over the others, or in a crowded nest (three or four chicks) she might even stop feeding the youngest all together. The dominant chick will naturally be the first in line at meal time and will be served the most. Also the oldest will often peck at the other chicks to let them know they should act subordinate. The younger chicks learn that they have to wait to get a taste. Then the younger chicks do the same to the chicks beneath them to establish the "pecking order."
So to sum up, there are several factors at work in the survival of a chick: Birth order, quantity of food, and feeding method -- just to name three. But this is the way families operate in osprey and eagle nests, where the ultimate goal is not to turn out the most chicks, but to turn out chicks that will be strong enough to fledge and survive to breeding age. Because perpetuating the species is what the whole nesting season is all about.
As humans though, we naturally cheer for all the chicks to make it, because watching any of them die is hard to do. So we wish all the chicks the best of luck and hope that this nest will beat the odds.
Until next time,
Lisa - webmaster
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