Thread subject: Powerpoint Presentation at Birders night.
||03/24/05 02:21 am
||This evening I should have MC'd Birders night at the university for the Victoria Natural History Society, however my voice 'cracked up' due to my recent bout with a mutant virus. Another director stood in for me. Our program for the night was titled 'OSPREYS', It was presented by a Biologist who had spent two years with these birds in Ontario. He had worked extensively with Eagles, Kestrels and other Raptors. He had some great pics as well as some interesting info, so thought I would share some 'nuggets' with you all.
The claw/talon of an osprey can close in 2/100ths of a second when they lock onto their kill/fish.Talon/claw is sharper than an eagles.
85-90% of the young that survive will return second or third year to their natal nest . A term called PHILOPATRY describes this behaviour....( love of home) Use it and impress your friends. ;-))
Western Ospreys seem to migrate as far south as Central America and northern South America.
Someone has estimated that the mother feeds her chick with morsals of fish that weigh approx 0.6 grms with each bite of fish.
The female chicks are always the heavy weights in the nest and the males grow faster of the chicks. They can sex young birds by measuring from the tip of the bill to the Culmen ( the central midline ridge running from the tip of the upper bill back to the base of the bill at the head end)
Adult females can be 25% larger than her mate.
Some harmful chemicals used in Asia drift in the upper atmosphere, cross the Pacific and fall again in the Rockys, so fish are contaminated in streams and lakes.These are showing up in the osprey eggs.
They have longer intestines proportionately to other birds. Its all that FISH and bone they eat. Needs more digesting.
In an average life span of 15-20 yrs they will clock up to 200,000 migration miles.
Last but not least, it has been OBSERVED that in order to lay one clutch of eggs (3-4 eggs) COPULATION activity amounted to 160 TIMES......That is a lot of activity for the male. No wonder he has to be smaller...that is enough to break a girls back.......;-)
||03/24/05 05:20 am
||Thanks Marie.....was glad to see the percentage of returning surviving chicks......I do believe reading that only 30-40% succeed in their first migration from their natal nest..however, once they make that, the percentage of returning 2 years later is encouraging.....Oh and thank you for the impressive word too! The chuckle was all that activity of the male....Thank goodness the female is bigger with a "strong" back!:)))....
||03/24/05 07:07 am
||Thanks Marie! I won't be too hard to work to work PHILOPTRY into a discussion about construction...My clients will be awed :-)
||03/24/05 08:05 am
||Marie thanks for all the great info ... not sure I can work PHILOPTRY into any discussion of bookkeeping or taxes but sure I can get the copulation stats into some conversation today.
||03/24/05 08:10 am
||Note to self: use *philopatry* at least once today...
Marie, great stuff! As always! ((hugs)) Thank you!
Hope you are feeling better soon!
||03/24/05 09:06 am
||Sorry , I missed spelled that word. There is an 'A' in there too
PHILOPATRY..........Shelley go it right.....Thanks Shelly.
Getting better every day..........
||03/24/05 09:15 am
||Celeste I think I may have got you a bit confused with that 85-90 % figure.........those figures suggest of the 20-40 % of the birds that survive their first Migration then 85-90% of those birds return to their Natal nests. Tiger is right about how few will make it back.....so there is only a slim chance that one of those birds on the nest right now is Freedom or liberty. The biologist said that it is usually the mature breeding males that return first to the nest so it could be Dennis with just some feather changes and slight differences in his brown head patches due to feather molts. That I am not sure of , and that question I forgot to ask the biologist last night...........
||03/24/05 10:55 am
||Marie - thanks for the interesting facts about ospreys. Imagine the strong forces that drive nature to repeat behavior that requires so much physical stamina and suffers huge attrition. (not to mention returning from a warm climate to Spring in New York). It kind of turns some of our ideas of what's important and necessary on its head. Sometimes I wonder what similar forces are driving us humans that we are as unaware as the ospreys are of theirs. (forgive me I have been studying Chinese philosophy Tao Te Ching)
||03/24/05 05:22 pm
||Thanks Marie.....I guess I "read" what I wanted to believe.....and your thoughts Cathy are very intriguing.....how alike are we? something to ponder.
||03/24/05 05:47 pm
||I have ben thinking a lot about what causes the birds to migrate.
Of course it must be the long hours of daylight which makes it worthwhile. I guess it would be much harder to raise three chicks at lower latitude.
That said I have no idea how many chicks the ospreys in Florida and Baja manage to raise.
||03/24/05 06:20 pm
||I was in Key West, Florida in February....and I saw several osprey nests....one that I was able to see had at least 2 chicks in the nest....What I would like to know is what makes some osprey migrate and not others....what is the difference in their makeup? Last year when I managed to get my hands on Poole's book which took me forever to borrow from the library....I kind of fast read about non-migratory osprey....but now having seen active nests in Florida I wonder.
||03/24/05 07:55 pm
||My advantage is that I have Poole's book :-) Sooooo....
In answer to your question:
"Migration is hazardous. Undoubtedly, all ospreys would be residents if they could get away with it. Yet one has only to look out a winter window to see why Ospreys leave most northern regions each fall. The birds themselves are probably not affected directly by the cold. Captive ospreys held outdoors but fed regularly easily survive winter in the northeastern United States. Fish, however, are coldblooded and thus sensitive to changes in water temperature. When temps drop, most fish avoid the colder shallows and surface waters where Ospreys can reach them. Thus even where northern lakes and bays do not freeze in winter, Ospreys attempting to winter over would probably starve.
If lack of fish is the ultimate reason for Osprey migration, one should be able to predict which populations will migrate by checking local winter temps. Major boundries between migrant and resident Ospreys are found in the southern U.S. roughly in northern Florida and southern Calif., and in Europe along the northern coast of the Mediterranean. Sure enough, a comparison of winter temps north and south of these boundries shows that winter freezes are regular only where migrants breed. Resident populations are rarely exposed to such low temps. Of course temps are often warm and food still plentiful when northern migrants leave their breeding grounds, so hunger is not the immediate stimulus for departure. Rather it is an Osprey's internal clock, subtle changes in the flow of the hormones, that no doubt generate the necessary restlessness. In this way, selection ensures the Ospreys vacate breeding areas well before their food becomes scarce, just as they vacate warm, productive tropical regions each spring when they return north to breed.
In summary, Osprey populations are migratory in regions where winter temps regularly go below freezing, reducing the availability of their cold-blooded prey. This, and the fact that Ospreys leave earlier and withdraw farther from breeding grounds than raptors dependant on hardy, warm-blooded prey, indicate that migration in this species is ultimately (even if not immediately) controlled by food supply."
Whew...I'm such a bad typist...please excuse the typos!
It seems to boil down to the luck of the draw. Some Ospreys were born in Florida so they stayed there :-) Poole does make it clear that even they don't stay at their breeding site all year. They too migrate a little further south. He says that their movement is "local" compared to the "long distance Ospreys".
Maybe more than you wanted to know :-)
||03/24/05 08:58 pm
||Thank you Cecelia for all that useful and informative info on OSPREY migration. I haven't been able to purchase this BOOK as it is out of print now. Lots of questions answered and thank you. Poole's book is called the Osprey Bible......as if you didn't know..:-)
||03/24/05 10:20 pm
||That is very interesting. Thanks so much for typing all that in for our benefit. I like the "internal clock" part. That's what I wonder - do humans have an internal clock that goes off with seasons or temperature or something else that we have failed to notice in our modern lives but which drives us as strongly as the ospreys that migrate? I just think we share so much with the rest of nature.
||03/24/05 11:33 pm
||Well Cathy........I would say I have an internal clock of sorts.......I feel my body closing down in late fall just as though I might be going into hibernation. I get slower and put a little extra weight on. My mood is less then boyant and I generally feel blue and sluggish. I smell death and dying in the air despite the fall colours. BUT come February I feel an awakening, an excitement stiring. Much more get up-and-go in my soul. I feel more upbeat and always want to be going somewhere. I smell the changes in the air in fall and Spring. As you can imagine Spring is my time of year......new beginnings, a rebirth of all living things. I love the lengthening days and the abundant sunshine . I love the colours of Spring and the warmth. My least favorite colours are grey and brown.........colours of late fall. I think we all are in tune with Nature. It is a question of having time to listen to our bodies.....