Migration

Question

I don't know if you got this unfinished blog, I pressed the wrong button...sorry. 
 
 Why don't the chicks come back for 2/3 years? 
 How do they 'know' when the 2/3years are up? 
 How do they know which direction they are going? 
 Will they come back to LG? 
 
 Thanks, in anticipation for answers!!!!

Jacki G · Answer

Maureen, I'm no expert and have asked the same questions myself - over and over!! Try Roy Dennis for answers - he has an amazing book you can order from his website http://www.roydennis.org/ Another place I found a few answers is a US site where Ospreys have been tracked for a number of years and a huge amount has been learnt from their travels. http://www.bioweb.uncc.edu/bierregaard/Index.htm It may take you some time to read all this but its perhaps something to bookmark for when the LG sisters have started their migration and we have dark winter days to fill.

LloydScott · Answer

Hi Maureen, 
 1. Many young birds will remain in wintering areas for their first summer or stop in the Mediterranean basin, some second year birds also stay in the south, and have given rise to persistent rumours of breeding in the African interior. for the vast majority of of second year birds do migrate north and attempt to attract a mate although sucessful breeding probably won't occur until the following year. Second year birds follow on average a month later than experienced breeders. 
 2. As the birds reach an age of breeding maturity they instinctively migrate to higher latitudes. An immature bird will even build a practice nest without securing a mate in thier second year. its simply a case of practice makes perfect. The urge to migrate can be demonstrated as an innate ability (best described as being determined at a genetic level and trickered by other environmental factors) - as is seen in cuckoos. Cuckoos for example never encounter thier parents yet thier behaviour is all naturally dictated as to where and when they migrate. 
 3. As a general rule bird migration movements are north-south and this has evolved as an evolutionary response to seasonal changes in the climate. So birds don't necessarily "know" where they're going, rather they move in a general north/south direction and use markers such as coast line to assit in thier navigation. 
 4. No, they probably won't return to LG, although it is possible. Breeding age birds may settle close to or far from thier birth sites - the maximum recorded distance from orginal nest site was 950km! this promotes better genetic mixing and keeps the population healthier! 
 Lloyd

Cirrus · Answer

Osprey - I'm in awe of your knowledge. Thank you for such an interesting, no, fascinating blog. I've really enjoyed the read. But am SO sad that so many juvenile Ospreys do not mature. I think that 06(01) was very sensible. Why go so far, anyway, if Portugal has the right temperature and lots of fish !! 
 Only 11 Chicks in 8 years. Gasp ! That's devastating.

Keith Rogers · Answer

My work colleague also works volunteer for the BTO and is an official ringer in Aberdeenshire. I sometimes attend with this work. Early in the season we spotted a lone Osprey with a Plastic Tag and BTO Steel Tag around the River Don in Aberdeenshire. Through binnoculars the colured tag was easily identified which my colleague reported to the BTO. This was a 3 year old male ringed from a nest in Perthshire. May be this information may help. We are not sure if this was the first return or not as it was the first reported ID since first migration. 
 Please report all sightings to the BTO to help build up a study - unfortunately it is very difficult to see the ID on the ring in most cases. Have managed to sight many Ospreys this year around Newburgh area (Good year this year) some with rings some without but the early one was the only positive ID we have managed.

Dunnock · Answer

Hi Maureen, I don't think it's an exact science as far as the ospreys are concerned. I remember that, in the early spring, they were saying that Nethy's transmitter would switch to more frequent signals again because they wanted to see whether she would get the urge to move North as the season changed. Presumably as the weather, or food supply or light, or whatever (seeing other ospreys?), changes they get the urge to start moving North. The first years maybe don't get it so strong, or not having done it North before they don't have such strong geographical clues and are more tentative. Obviously one occasionally makes it all the way back the first year, and perhaps some take till the third or even more. I would think the urge to find a mate becomes much stronger at some point and affects the distance thay are prepared to go. The range of overwintering and also stopping for the summer is quite wide. They were saying last year that migration to the SW of England might be possible in the next few years and my husband saw a summer one on the Loire this year. I presume one of the reasons they are tagging them is because they are researching all this.

Annette in SoCal · Answer

Is anyone on this blog? I'm just wondering if you're getting the same all-blue picture on the LG cam that I'm getting (it's midnight UK time).