First Real Results From Breeding Bird Survey
News from the BTO
24th October 1996
The very first results of a new nationwide survey of Britain's breeding birds, comparing 1995 with 1994, show they were, on balance, doing well. Twice as many species increased significantly as went down. No change was detected in the populations of 58 species and 27 went up with only 12 declining between the years.
The Breeding Bird Survey is organised by the British Trust for Ornithology in partnership with the Joint Nature Conservation Committee and the Royal Society for the Protection of Birds. It relies on the skilled participation of many hundreds of amateur bird watchers who carefully record the birds they see and hear on two visits each year to their BBS plots. Their records on two transects one kilometre long through the same 1-km square of the National Grid are the raw material for a massive number-crunching exercise at the BTO HQ in Thetford.
Even before the birds are recorded the computer programs have selected, at random, the squares to be surveyed. These cover the whole country - mountains and salt-marsh, cities and farmland, the cosy Home Counties and the remotest Scottish Glens are all represented. Almost 1300 squares were covered in both years.
The bird records are then input - often relating to hundreds of individual birds of 50 or more species for a single square. The results are very exciting. BTO survey work of this sort in the past has been concentrated on very detailed and time-consuming mapping surveys (CBC and WBS) particularly of woodland and farmland plots. Only about 300 are surveyed annually and much of the country has been left out of the results which do not cover by any means all of the species breeding in Britain. The new survey results agree very well with the traditional surveys but cover all the breeding species.
Significant changes (those which there is only 5% chance that they are not real) were recorded for the following 28 species. Only birds recorded in at least 50 squares are included.
Species No. of squares Change Grey Heron 461 +21% Mute Swan 140 -22% Greylag Goose 75 +169% Canada Goose 265 +24% Buzzard 337 +11% Kestrel 586 -16% Coot 155 +21% Oystercatcher 202 -26% Golden Plover 89 -63% Lapwing 543 +21% Woodpigeon 1237 -11% Swift 827 -9% Green Woodpecker 457 -13% Sand Martin 88 +52% Swallow 1043 -17% House Martin 627 +12% Meadow Pipit 519 +7% Yellow Wagtail 166 +24% Pied Wagtail 814 +21% Wren 1250 +14% Robin 1193 +11% Redstart 116 +31% Stonechat 69 +57% Wheatear 249 +32% Whitethroat 758 +13% Chiffchaff 691 +7% Willow Warbler 990 +16% Goldcrest 420 +30% Marsh Tit 136 +36% Blue Tit 1147 +8% Great Tit 1112 +5% Jay 493 -26% Magpie 1008 -5% Raven 148 +35% Starling 1098 +8% Greenfinch 952 +6% Linnet 859 +15% Bullfinch 459 -17% Yellowhammer 809 -8%
Species which do not appear in this list either showed no significant difference between 1994 and 1995 or were present in less than 50 squares in both years. This enterprise will become more and more important as the years go by and new volunteers will be needed each year to make up for people who have to drop out and to cover all the squares selected for coverage.
It is really interesting getting to know the square you are covering - so volunteer now to Richard Bashford, BTO, The Nunnery, Thetford, Norfolk IP24 2PU.