Friday, April 13, 2012

Overnight evacuation!

At some point during the night I awakened and could hear Greenland White-fronted Geese passing over the house. Not a lot, but enough to be heard. The relevance of this is that we don't have a roost at the SW tip of Islay where I live, but small numbers (reduced this winter ) regularly  feed hereabouts, but usually move off to roost. Moving birds at night could be "feeders", given it was partial moonlight,  but are more likely to be real "movers" at this time of year!!  I elected for the latter and concluded they were very probably from the wintering population in Ireland that were hedge hopping over Islay on their way north. And so to bed as the Bard said! ( at least I hope it was him!).

Next on the evacuation agenda as I travelled north up Loch Indaal to complete some observations on eagles was the chappie below.


Given it was so calm I couldn't make out the drooped flag of our overnight visitor clearly making haste on an 0630 hours reveille sailing!! Only a single gun, so no real threat it has to be said ( click the picture for a better look!! ). Nothing more than an overnight berth in this case, but it perhaps should turn our thoughts to other far flung island communities who have witnessed such "appearances" in the past!!

On to Jura, where a few hours of observation confirmed the eagles under observation were certainly still in residence with the "old man" circling around at one stage and indulging in a series of five shallow dives over the territory. Terrific stuff.  Attaboy.....it's all show ladies, don't be fooled. Victims of our body chemistry!!

Of equal interest was a single ( nominate ) Canada Goose flying north up the Sound, an adult Glaucous Gull floating past southwards, and evading being photographed ,and some nice views of Hen Harrier and Red-throated Diver whilst on the island.  The northward migration of gulls has noticeably reduced and precious little appeared to be on the move compared to recent times, even Black Guillemot numbers had gone down.

At the end of the afternoon I travelled to the RSPB Loch Gruinart Reserve....the light's better in late afternoon /evening!! Well I suppose the only  descriptions that might apply would be " Gone , but not forgotten " or " Now you see them, now you don't".  What had been an accumulation of at least 9000/10,000 Barnacle Geese in the overall area in the last couple of days was much reduced. Whilst obviously some remained , a guess being at 10 %. , the majority appeared to have just left!!!   Obviously an overnight evacuation of some significance, which begs the question of how the birds actually determine the precise time to set off. For some time I've wondered whether improving barometric pressure can be sensed by birds and that, based on this, they then take a decision to set off in what is clearly supportive high pressure conditions. Well, it has merit , although last autumn I understand birds, in this case Greenland White-fronted Geese, were actually caught out when coming south and affected by storms en route, which led to losses. So it may be a bit of a non-starter as a permanent hypothesis!! The much lower counts of the latter sub-species over the winter  has led to increasing concerns about its future, so conditions en route,as well as breeding success previously, can obviously have a meaningful effect on particular populations. But that we could influence things beneficially..........

 Some people are intrigued by the navigational abilities of birds, but this ability to determine precisely when long migrations happen is intriguing....daylight length?, other reasons?...who knows?.  Whatever the trigger, my thoughts are with the birds now battling northwards in calm or turbulent conditions and my thoughts are with, already,  your autumn return. It will soon be so silent without you!!!