Friday, August 31, 2012

BTO Breeding Bird Survey Report 2011.

The above report is the seventeenth in the series and , besides much other crucial data and information, includes trends in breeding bird populations in Scotland for 2010-2011 and 1995-2010. As such it provides an important barometer of change which can obviously be the basis for other comparisons and direct interest towards conservation policies. It's also fascinating to focus the results into one of local interest and see if the trends follow what is appearing at a much wider level.

In all 358 BBS were surveyed in Scotland in 2011, with 156 species being recorded within them of which the most widespread were Chaffinch, Willow Warbler and Woodpigeon. Of the 60 species for which trends could be calculated, eight have declined significantly and sixteen have increased significantly sine the commencement of the survey.

Birds that declined in Scotland between 2010 and 2011  included Kestrel, Skylark, House Martin, Mistle Thrush, Grey Wagtail, and Reed Bunting. The only one of these, in a local context,  that I would be a little sceptical about is Reed Bunting given we carry a seemingly widespread and successful population that , as yet, appears to be pretty stable. Of the other species, then I think full acceptance of the trends can be recognised.

Between 2010 and 2011 Bullfinch increased the most in Scotland,  along with four warbler species which showed large increases (  Chiffchaff, Willow Warbler, Blackcap and Whitethroat ).  Again, based on a gradually increasing incidence of sightings,  I would contend the situation on Islay mirrors the results in a modest sense.

The most severe declines since the start of the survey have been shown by Kestrel, Curlew, Lapwing, Swift, and Starling. I suppose, with the exception of Swift which doesn't breed on Islay, general agreement could again be offered to the conclusions and other species added to the mix too. Based on personal impressions assembled over the same period, species that might be added to the above, as far as Islay is concerned, are Tree Pipit, Meadow Pipit, Snipe and even Peregrine, which I appear to come across with reducing regularity. Obviously such impressions are extremely subjective , which underlines the value of long standing surveys such as BBS and the need to have as many plots as possible in order to generate results for a wide ranging selection of breeding species.

In parallel to the above declines, the greatest increases since the start of the survey have been with Chiffchaff, Great Spotted Woodpecker, Blackcap, Goldfinch and Whitethroat.  Certainly the incidence of woodpecker records on Islay has increased over the decade, although breeding, or even presence throughout a breeding season, has yet to be proven. Again, it would be difficult to deny that the presence of the last three species in the list appears to be more obvious than previously. Clearly seasonal differences occur and lend hope to what might then be a continuing positive trend. In this context the apparent numbers locally of Cuckoo and Whinchat this season have increased, but the numbers locally of Northern Wheatear appear to be reduced. In a very local context, on Wednesday, I had my highest count ever of Woodpigeon on Islay ( 28 ) at a single location, having had several other small parties during the day too.  Given its apparent success in urban environments, and a BTO Press release this week reporting it is now the third commonest visitor to gardens in the UK ( behind Blue Tit and Blackbird ), one could easily assume it might be gradually increasing generally. It's not that common a bird here, although widespread, so we may well be joining the common trend ( something we try hard to avoid on Islay in a non-biological context!!).

All such again emphasises the need for long term monitoring and the absolute value that the BBS survey brings to the debate. 
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