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Thread subject: Alan Poole
Name Date Message
Celeste 05/28/05 05:55 am Cecilia was kind enough to give me some articles by Alan Poole on Ospreys. Though they can get quite technical, the overall feeling I had reading them was how wonderful to study something in depth that one loves! To be able to do that in one's lifetime is certainly a priviledge.

Some of the studies were questions that take what we discuss on the board several steps further.

I have 3 articles, but here is the first study.....
For example, Does the amount of food a female gets during courtship affect the size of her eggs, how many, her weight before and after.

Some interesting points.....

1. Females with older mates, (5 plus years), and those that had the same mate for 2 or more years, consumed the most fish. It was concluded that the food intake of the female depended on how much the mate was willing to share, and not by how many were caught.

2. It was concluded, that variation in the amount of food consumed by females did not significantly influence egg size or clutch size, nor did females laying 4 eggs eat more fish than those laying 3 eggs. Also, how much fish they ate did not influence the size of the brood at fledging

3. Even when the "control" nests were given extra fish to eat, it didnot affect clutch or egg sizes. However, the males in those nests would only forage for fish after they had eaten what was given to them.

4. There was no significant connection between the amount of fish females ate and their body weights at laying. In fact most female ospreys gained little weight during courtship. Females, return from migration close to the weights they are when they are laying.

5. Females who ate more fish did lay eggs earlier. Laying dates also are connected with the age of a pair, the number of years a pair has bred together is relevant also. Older pairs and pairs who have the same mate generally bred earlier.

6. Interestingly, pair copulations didn't necessarily happen right after a mate brought a fish! It was found that pairs attempt to mate even if a female had not eaten!

The study gets extremely intricate, and impossible to repeat here.....I am only giving highlights....

Males who have been with a female for a while seem to be more responsive to females begging. And in our nest, we sometimes observed our Dennis hesitant about turning over a fish during courtship days, Poole observed this with males who had new mates.
And finally, it was also observed that in nests where the male wasn't bringing enough food, a female would sometimes beg at a "bachelor's" nest and mate with that osprey. Hence it is suggested that a key function of courtschip feeding is to ensure mate fidelity. Because females are left alone at nests while males are fishing, and because well fed females defend their nests, courtship feeding may function also to mate guarding to reduce the female from "wandering" and to increase the male's confidence that the chicks are HIS!


Shelley 05/28/05 06:18 am Wow!

You know, now that we have the exclusive priviledge of observing inside the nest, seeing what truly has never been seen before, and really getting to *know* our osprey, around the clock yet without direct interference, it amazes me how such studies WITHOUT this type of observation are even possible, let alone conclusive. Yet obviously, they are. Obviously, they are done on tagged birds, too. What I'd really love, though, would be if Alan Poole (and others who conduct and write such studies) were to become a regular here, and see what we see, and post his observations and thoughts and questions here......


Thanks, Celeste and Cecilia, for sharing more insights and info with us. I always look forward to learning more from you guys!
Tiger 05/28/05 06:18 am Oh there are so many interesting things in that. As you know I have been talking about this fidelity thing for a long time and everything written above is so true!

I think our Dennis was reluctant about supplying fish until he saw the CHICKS!

Celeste 05/28/05 06:24 am Cec said that Poole did take a peek at our site a couple of days ago. Yes wouldn't it be something to have him participate. I would love to know what he actually "thinks" of our discussions on osprey.
Tiger 05/28/05 06:29 am There is no reason why he should not. I am a member of a discussion on another topic and many of the "world experts" are present there.
Marie 05/28/05 11:22 am WE WILL CERTAINLY HAVE TO WATCH WHAT WE SAY THEN...........but it would be wonderful to have the experts with us.........from time to time

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Tom Throwe
Last modified: Sat Feb 18, 2006