Re: PD, ML and GN (was Great Northern? Real!)


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Posted by Jock on August 26, 2008 at 13:27:56 user Jock.

In Reply to: Re: PD, ML and GN (was Great Northern? Real!) posted by Andrew Craig-Bennett on August 26, 2008 at 01:03:52:

I hesitate to cross swords with Andrew, who I regard as one of TarBoard's
GAs (Great Authorities), but having thought about the Great Northern Diver
migrations, I'm not at all convinced that the GND's nesting season could not
mesh with the Swallow's main summer holiday.

A UK wintering individual of the species Gavia Immer sets off for his or
her breeding grounds in "late April or early May" and returns to Britain in
August or so.

But surely the GNDs that very occasionally nest in Northern Scotland are not
UK wintering GNDs? The UK wintering GNDs - with the exception of some
non-nesting individuals - will all have gone off to do their nesting elsewhere
by, as Andrew tells us, early May. However, GNDs that winter further afield
just might decide that enough is enough and that Scotland's Western Isles will
do just as well as Iceland, particularly if they have been wearied by flying
against strong contrary headwinds, on their return journey.

If we postulate that AR's GN GND is one that has migrated to Scotland to nest,
rather than one that has mated prematurely and not yet migrated from Scotland,
add the fact that GNDs start nesting in spring and can make several attempts at
nesting, and bear in mind that they have been observed arriving at their nesting
grounds as late as 20 June (Audubon), then surely the problem is solved.


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