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Message: <blockquote data-quote="Steve Dudley" data-source="post: 1708704" data-attributes="member: 5172">Eagle Owl was present in Britain up until the last ice age (c.10,000 years BP) (Stewart 2007) but there is no evidence that supports natural occurrence since, and since the land bridge between Britain and the Continent disappeared (Melling et al 2008). If anyone who hasn’t seen the latter paper then please PM me your email address, or email me, and I will send you a PDF.As to stable isotopes, changes in climatic conditions can be compared (e.g. comparing a movement between two different regions with significantly different rainfalls). Care needs to be taken when looking for differences between areas within what is considered to be the same climatic region (e.g NW Europe). If a bird moved from a 'wet' area to a 'dry' area, even within the same climatic region, this could result in an obvious indication in stable isotope analysis. So, for arguments sake, the Norfolk EO moved from a wet area and died in a dry (Brecks - a low rainfall area) area could show this. But how you would prove that the wet area was Scandinavia over say Northern England (were EOs have bred successfully in recent years ) would I expect be very difficult as I understand they would have similar isotope signatures. By contrast, isotope analysis of Baikal Teal (Votier et al 2009) was relatively easy because of the vast differences in isotope signature between the low-rainfall far northeast Palearctic and the high rainfall west. It is also worth remembering that isotope signatures of feathers reflect the diet of the bird when it was growing its feathers. If a captive bird was fed on e.g. grain from eastern Europe, or on rats that had been fed on pellets made from grain from eastern Europe, then the bird would show a false signature suggesting east European origin.  In short isotope analysis of feathers is not the silver bullet that most birders seem to think it is, but it can be useful in certain situations.RefsMelling, Tim., Dudley, Steve & Doherty, Paul. 2008. The Eagle Owl in Britain. British Birds 101: 478-490. Stewart, John. 2007. The fossil and archaeological record of the Eagle Owl in Britain. British Birds 100: 481-486.Hi   Votier, Stephen, Bowen, Gabriel J. & Newton, Jason. 2009. Stable-hydrogen isotope analyses suggest natural vagrancy of Baikal Teal to Britain. British Birds 102: 697-699.</blockquote>

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