Re: Osprey Q & A

ClaireM

It is stated on the LotL thread that the adult Osprey mortality rate is 10%.  

Is the overall juvenile mortality rate known in terms of percentages?

It is thought to be about 80%  but for some reason the ospreys born at Rutland seem to do rather better than that.

 

I think it's 17 returns from 37 fledged at Rutland between 2004 & 2010 & obviously still time this year for more returns. I think the nests from 2007 have been the only blank year.

Vespa Crabro

I think it's 17 returns from 37 fledged at Rutland between 2004 & 2010 & obviously still time this year for more returns. I think the nests from 2007 have been the only blank year.

 

In 2003 there were 6 ospreys fledged in England and as far as I know none were ever seen again.

In 2004 there were three ospreys fledged in England and every one of them survived at least three years. There was a fourth fledged in Wales and some people believe that he is good old Monty the male in residence at Dyfi. Sadly the Welsh chick could not been ringed so we will probably never know.

Now those figures are truly dramatic. They do suggest that there some factor which varies from year to year. I think that the most likely candidate is weather.

Vespa Crabro

I think it's 17 returns from 37 fledged at Rutland between 2004 & 2010

Hi Vespa

I evidently have one missing from my notes: I can account for

• 9 offspring of 03(97) [5R, 5N, 30(05), 32(05), AW, Nora, 00(09), 01(09) & 28(10)]
• 6 grandchildren of 03(97) [03(09), 11(10), 12(10), 24(10), 25(10) & 30(10)]
• 1 other [06(09), from site O]

Can you remind me who the other is/ was? And am I right in thinking that the identity of the site O male in 2009 has never been stated? Other than evidently not one of 03's progeny.

Rachel

I think your missing one is Nora's brother 05(08) who returned to RW in 2010 as a 2yo, but not subsequently.  

Can't help about Site O I'm afraid. AW's biography, first published in 2011, says he started breeding at Site O "last year" i.e. 2010,  but at least 2 chicks hatched there in 2009 including 06(09) who you mention above. 

Was it you that was planning to have a go at compiling a Rutland Water family tree? Good Luck!!

Sue - it's more or less done. Layout is the difficult bit - ospreys are more prolific (and usually have more partners) than human families :-D

Just waiting for this year's chicks to be ringed (plus any info we can prise out of them about the other nests...) & then I'll send Tiger a copy for the website or anything else he wants to do with it.

 

EDIT - looks like I had a mistake in my notes, then: I had the 2008 site B chicks as 01, 02 & 03... Now sorted. Thanks!

Rachel

...& then I'll send Tiger a copy for the website or anything else he wants to do with it.

Hi Rachel, it is me who inputs the website stuff so look forward to seeing a copy myself. What software have you used to compile it?

Hi Chloe. Will do. So far it is just manuscript - I haven't tried to put ospreys into my family history software (yet...) Now that you've put the idea into my head, who knows?! Might be a suitable project to test the new software with...?

For website purposes, scanned & emailed/ posted on FB might well be easier anyway.

Tiger

It is thought to be about 80%  but for some reason the ospreys born at Rutland seem to do rather better than that.

 

Thanks for that info - and for all the stats and recordings provided by others.

I do find the topic very interesting.

Sounds great Rachel. Good luck with whatever you decide on, and thanks :)

Some stats from a study of Canadian ospreys:

"According to the most recent estimates, about half of young Ospreys die in the first year; the mortality rate in subsequent years is between 16 and 19 percent. Available banding data (20 000 individuals have been banded in the last 60 years), indicates that Ospreys can live for 15 to 20 years; however, some individuals have lived much longer. The longevity record for the species is held by a banded bird that died, probably from a bullet, at age 35. Unfortunately, we don’t know whether this individual had bred every year up to its death. The greatest recorded number of breeding seasons for a single bird is 23. "

Sue C

Can't help about Site O I'm afraid. AW's biography, first published in 2011, says he started breeding at Site O "last year" i.e. 2010,  but at least 2 chicks hatched there in 2009 including 06(09) who you mention above. 

Sue/Rachel, I've never read anywhere that's confirmed the identity of the 2009 male at site O. However putting 2 & 2 together & hopefully making 4; it was early spring 2010 when 32(05) & 06(00) disappeared, I've always assumed that 06(00) was shot & AA/AW(06) took over the nest, then bred successfully. (5R(04) certainly took over 32(05)'s mate that year. (Please note I have no inside knowledge about this)

Hi , what is this?? ( Next to the nest web cam)

Hi Fish - it looks like a bag to me - the sort of thing they collected the chicks in!

WendyBartter

Hi Fish - it looks like a bag to me - the sort of thing they collected the chicks in!

Hi WendyB, 

But why is it there this time of night??? Some one trying to nick the chicks???