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Thread subject: Continuation of Alan Poole's "Ospreys"
||05/06/04 06:20 am
||fyi.....this book was printed in 1989...to date I am not aware if there are any more books out there that dwell exclusively with the studies of this bird since '89...thus anything I write is based on these studies from '89.
1. osprey eggs are about the size of hens eggs, (never would think that looking at the cam!)
2. the first eggs are larger that the last laid and they hatch in the sequence they are laid.
3. chicks 3 and 4 are less likely to survive. There were several indications the reason these chicks do not survive is there is not enough fish brought to the nest. The female tries her best to feed all the chicks, and will deny herself and lose weight in order to do this. As the chicks grow and especially chick one who becomes more hungry and aggressive, that chick will "bully" the younger chicks to submission, and they eventually can starve to death or get pushed over the nest. As we saw last year if chick one is satisfied, then that chick will allow the others to be fed. The female does not interfere as it is easier to feed only one or two chicks. In extreme cases where fish is really scarce and the mother is starving and losing too much weight, she will abandon the nest. The female will receive 15-20% of the food the mate catches. The male needs a lot of energy to fish, thus he eats more and away from the nest also.
3. when we see the osprey wiggle down in the nest it is to bring the eggs into full contact with their brood patches, (bare vascularized sections of skin on the breast). The nest "cup" is usually so deep that only the head and sometimes the back of the parent osprey is visible if you are looking at the nest from the ground. Both male and female osprey have brood patches, and the female incubates longer and always takes the night shift. Individual males vary the time they spend incubating and there really isn't any explanation why. Just because a male doesn't incubate much doesn't mean he is catching more fish----he is perching more than other males do.
4. Chicks are born wet and helpless and the strongest part of their body is the neck, which helps drive the "egg tooth". If a hatching egg is handled you can hear the chick's faint peeps in the eggs as it is pecking itself out of the egg. Chicks do not fear humans.
5. first 10-12 days the chicks are kept warm with their "down". After the "down" becomes denser in the next 10-15 days, they crouch at danger. At 10 days they are more mobile approaching mom for food and fighting their siblings when food is scarce, (as many of us observed last season). Of course there is that funny scene when the chicks back up to eject their feces over the rim of the nest! At 2 wks, feathers appear, and at 20-25 days the serious feathers appear. At 30 days, they have achieved 70-80% total body weight. The male osprey weighs less, matures faster, and learn to hunt faster than females.
6. Young ospreys exercise their wings 10-15days before fledging---there is a lot of confusion when the chicks are doing this and the female will tend to avoid this by perching nearby.
7. when osprey nests are close together, chicks will visit these other nests, especially if they have the opportunity to be the "dominant" chick in that nest. Parents tolerate the stranger chicks because they probably don't recognize the foreign chick.
8. Parents will "teach" their chicks to fish by luring their young by flying past with a fish. Or they will drop a fish in the water, encouraging the young chick to stoop for the fish. Young female chicks take longer to start hunting than males, and they also mentioned that the male chick will fledge first cause he weighs less.
9. food supply relates to breeding success. In the 30'and 40's ospreys on Gardiners Island fledged 2-3 chicks as there was a nearby commercial fishery. When that fishery no longer existed, the number of chicks per nest declined. Another reason to protect our enviornment's food supply for ALL animals.
Well that is it for now. I love this book cause there is just so much to learn. These are just very brief highlights. Thank you all for your lovely words. I am so fascinated by all that I read I just have to share it. My husband may not go to the library for me anymore though!!!!!
||05/06/04 06:26 am
||One more thing......average incubation is 35-43 days, (for all of us who are participating in the "pool".) Not clear whether it has to do with efficient incubation or differences among the eggs. If eggs are destroyed for any reason, a pair of osprey will usually lay a 2nd smaller clutch 3 weeks later.
We also have to hope that we have decent weather this season as very wet weather affects the food supply.
||05/06/04 07:09 am
||As always, Celeste, thank you so much. A couple of questions, which may or may not be answered in that book. (if the answers are obvious to all but me, please forgive my ignorance!) One, why would wet weather affect the food supply of the ospreys if fish comprises most of their diet? It's not like fish get *soggy*, is it?
And my other question was, you had mentioned that chicks do not fear humans but I wonder, would they *imprint* on them , as ducks and other animals might, if handled by humans from birth (and is there any documentation of ospreys being born and raised in captivity?)
I'm going to look for this book at my local used book store, where I've often found obscure or out-of-print books!
||05/06/04 07:15 am
||Thank you so much once again Celeste. Hopefully you are succeeding in creating a much more knowledgeble pool of osprey enthusiasts. If each of us can pass a little onto our kids and grandkids it can only serve to help these beautiful raptors to survive for many future generations. Thank you again
||05/06/04 08:17 am
||Hi Shelley, checking this before running off to work......Osprey do not care to be handled and do not do well in captivity. Falconers have not been able to succeed in using this bird for sport because of this. It only mentioned that when a female is hooded, (perhaps to be banded), she will settle down, but not male osprey. There is a particular technique in banding the osprey chicks where some sort of dome is put over the nest and the whole process takes 35-40 min. There are people who studied this bird who would habitually climb the nest very quickly to get a closer look at the nest, etc. However, the author mentioned once that an osprey flew so close to him to ward him off that he almost lost an eye. Last season I had read on a website somewhere in New Jersey I believe had a "rescued" osprey that they used for educational purposes, as he was no longer able to fly. But most websites I read say that osprey do not do well at all in captivity and usually will not eat. As I mentioned, chicks do not fear humans when they are "first born", after a number of days they "learn" to fear and crouch in their nest when there is danger. Last year for example, (it is in an archived video), the nest was being threatened, and the chicks instinctively knew to crouch low while the mother hen protected her brood.
Perhaps there have been more recent studies, but according to this book osprey do not fare well in captivity at all.
Why does weather affect the osprey......well though certain conditions of weather "favor" fishing, if it is a very heavy rain season, they just can't see the fish and osprey prefer to perch and "look" for their catch rather than circle above the water, (they lose about 10% of their energy that way). If they can't see the fish they can't eat!
||05/06/04 08:27 am
||one more thing....regarding fish supply...a popular fish that the osprey like to eat is called the menhaden cause you can practically catch these fish with your hands, they are very close to the surface. Last season I read that this fish supply is not as large as it used to be due to water conditions,(enviornment), this in turn affects the amount of fish the male osprey can bring to the nest. The more fish he can bring the less chance of their being a hungry nest, which in turn enables more chicks to survive.
||05/06/04 09:08 am
||Celeste, I hereby nominate you for the Golden Feather Award as the Osprey Tutor Of The Year!! :~) Many Thanks.
||05/06/04 09:30 am
||I agree with Ron!!!
A couple of weeks ago I did an international, internet search for Alan Poole's book and found one in a used book store in England, which I bought and am waiting for. I should have just gone to the library like Frank :-) There were 5 more copies available in various European bookstores in case anyone is interested but we may not need our own copies if you can keep Osprey 101 going :-)
||05/06/04 10:45 am
||well another great post Celeste !
Shelly.......wet weather=flat dull water surfice=cant see fish from the air.
Last year and anyone please correct me if Im wrong, we had a guest commentator.A Lady. Who along with other Osprey nuts :) would get chicks and bring them to other areas/nests to fingerprint them. They if I recall correctly would then feed the chick with hand puppets. I think the area was Pennsylvania. It was a very elaborate setup so the chick never saw the human. Does anyone else recall this ?
||05/06/04 11:54 am
||I wasn't here, obviously, but I recently saw a show on tv (*Nature*, I think it was) about something very similar. I can't remember if it was ospreys or some other bird, though.
Thanks, Mickey and others, for the clarification. I claim complete ignorance when it comes to this sort of thing. But I'm trainable..;-)
||05/06/04 12:16 pm
||Mickey, I think this is the info you are referring to (it's one of
last years weekly commentaries):
June 30, 2003 Commentary: The observations in this commentary are based on my observations and experiences as a volunteer for the Osprey Introduction Program at Tioga-Hammond Lakes, Tioga, PA (and later by osprey choice at the Cowanesque Lake, Lawrenceville, PA) during three summers of the 5-year project and during several follow-up years. Dennis Puleston's influence is the reason for my family's interest and involvement in this project and for our support of the Dennis Puleston Osprey Fund. More details about our connection with Dennis are related in an article entitled "Remembering Dennis" in the Spring 2003 issue of the Post-Morrow Newsletter, also available at the corresponding link on the Homepage of this website.
ΓΆ€” Marilyn Porto Abbey (Retired teacher; osprey watcher)
In 1990 through 1994, biologists worked in co-operation with the Army Corps of Engineers and with the support of volunteers to establish an inland breeding population of ospreys near the South-central border of NYS and the North/central border of PA. The project used a technique called "hacking" developed by Dr. Charles Schaadt, Penn State University and Dr. Larry Rymon, East Stroudsburg University. Hacking involves the process of removing young osprey chicks from "donor" nests and raising them in a tower in enclosed artificial nests at the reintroduction site. Near the time of expected fledging, the enclosure screen is lowered to form a platform from which the young ospreys are free to fly when they are ready. Volunteers assist in weighing, banding, reporting observations, feeding the chicks their normal diet of fish until the birds are fishing successfully on their own. The ospreys become imprinted on the area, migrate in the fall to Central or South America and return from their wintering grounds in 1&1/2 yrs., when they are mature.
Practice Take-Offs: A remarkable incident at a Hammond Lake Hacking Tower, Tioga, PA, summer 1993. This incident demonstrates the amazing skill of young ospreys: One of our ospreys was standing on the edge of the tower platform exercising her wings. At one point, she lifted off about 6 inches and was watching her dangling feet when a gust of wind came and tumbled her backwards off the platform. At about 3-4 feet off the ground, she flapped her wings and righted herself. She arched around in a most graceful flight and landed in a dead tree about 100 yards away, as though she had been doing it for years!
Concern: There has been some concern about the belief of some people that the female osprey won't return to the nest to feed the chicks if humans go near the nest or disturb the chicks in any way.
Unlike condors and vultures, ospreys can't smell worth a darn, so human scent is not an issue here. Maybe that's how they can ignore the smell of decaying fish parts after so many fish meals have been served in one place!
Here is an eye-witness account: The scene is the first natural nest in our area, built by a pair of ospreys, on a dead tree in Cowanesque Lake, Lawrenceville, PA. in 1994. The biologists/naturalists approached the nest by pontoon boat. The purpose was to band the chicks for research (tracking, survivors, returnees, etc.) The adult female flew off the nest and the male soon joined her flying around overhead. The three chicks were banded in approximately 20 minutes, and from the time we left, the female parent was back on the nest in 20 seconds. They did scold us, but they never tried to attack us, and our interruption didn't discourage them from coming back in a flash! The chicks thrived and lived to fledge and fish on their own. The ospreys have returned to that same nest for nine years and have raised a total of 27 healthy chicks.
To see the rest of the 2003 commentaries
go to the DPOF Home page and click on the "2003 season" (in the sidebar). Then click on "Commentary" and that will bring up the archives. I think they are worth reading again or for the first time for any of the new people!
||05/06/04 01:21 pm
It's a good suggestion to re-read the 2003 commentary. I know I read all of it last year but when I return, with my head re-calibrated from the new information I've learned this year, it looks new again. I either see something I overlooked the first time through, or I read it with new understanding.
I guess I'll always be a perpetual student! :~))
||05/06/04 05:21 pm
||So I did a google for the book and my my my this site had alot of hits :)