Latest results from the BTO/JNCC/RSPB Breeding Bird Survey (BBS) reveal that the Grey Partridge is still in decline. Press release follows....
The annual BBS survey involves 2,300 birdwatchers, experienced volunteers who are out at dawn to count the UK's birds.
Volunteer birdwatchers involved with the BTO/JNCC/RSPB Breeding Bird Survey in the summer of 2005, counted nearly 1 million birds on 2,879 1-km squares throughout the UK, recording 221 bird species. This year, there is good news for Song Thrush, but bad news for our native Grey Partridge. Many of our migrant species, such as Chiffchaff and Tree Pipit returned in smaller numbers in 2005 compared to 2004. More details about these species are given below.
THE GENERAL PICTURE
â¢The Breeding Bird Survey (BBS) is administered by the British Trust for Ornithology (BTO) from its headquarters in Thetford, Norfolk. Across the UK, voluntary Regional Organisers play a vital role in coordinating the efforts of local birdwatchers. Volunteer birdwatchers are assigned 1-km squares that they visit three times in the season. Having got up very early in the morning, each volunteer spends about two hours counting all the birds they see and hear along their chosen 2-km route.
â¢The BBS started in 1994. This carefully designed, yet simple survey has attracted many participants. The good level of coverage throughout the UK means that we are able to report separately on changes in bird populations in England, Northern Ireland, Scotland and Wales and in nine English Government Office Regions, as well as for the UK overall.
â¢Of sixteen widespread species that are red-listed in Birds of Conservation Concern (BoCC) on the basis of long-term population trends, nine declined significantly on BBS squares between 1994 and 2005 (see Notes to Editors). Five red-listed species (Song Thrush, Grasshopper Warbler, Marsh Tit, Tree Sparrow and Reed Bunting) have increased significantly in the same time period.
Grey Partridge continues to decline:
There was no halt to the decline in Grey Partridge, with numbers down by 14% between 2004 and 2005, which means that they are down by 40% over the entire BBS survey period (1994-2005). This species has been declining for several decades (87% since 1978 - as revealed from long-term analyses). Our native Grey Partridge is now a scarce bird across most of the country, being found on only 9% of surveyed BBS sites in 2005, a figure which compares very badly with that for introduced game-birds such as Red-legged Partridge (22%) and Pheasant (69%).
This decline has largely been caused by the effects of agricultural intensification, more specifically the effects of herbicides on the food plants of young chicks' insect prey. Despite years of research and the application of a government Biodiversity Action Plan, the continuing decline shown by the BBS suggests that efforts to boost the population have not yet been successful. Perhaps good take-up of options such as conservation headlands and game cover crops in the new Environmental Stewardship scheme will have more success.
Song Thrush success:
The latest BBS figures show that the recovery of the Song Thrush is continuing, with an 18% increase in numbers in the UK since 1994. The Song Thrush underwent a dramatic decline, which began in the early-1970s and levelled off in the 1990s. This decline was driven by the falling survival rates of juveniles in their first year of life, caused by agricultural intensification, the drainage of damp ground and the depletion of woodland shrub layers through canopy closure and deer browsing. The continued recovery of rural Song Thrush populations will require the provision of adequate nesting cover in scrub and woodland understory, the presence of grazed grassland in arable-dominated areas and damper soils in summer. The latter factor may explain why this species has prospered in the west of the country, and continues to decline in areas receiving less rainfall, such as East Anglia.
Migrants return in smaller numbers in 2005:
The greater than normal numbers of migrant summer-visitors recorded in 2004, was not repeated in 2005, with 17 of the 26 summer-visitor species monitored by the BBS, declining between 2004 and 2005. The most notable declines were for Chiffchaff (down 27%) and Tree Pipit (down 37%).
For many long-distance migratory species, this year-to-year variation is driven predominantly by conditions on the African wintering grounds. Whitethroat, Cuckoo, Willow Warbler and Sand Martin all winter south of the Sahara, and years of poor rainfall have been shown to coincide with falls in the British breeding populations. The declines presumably reflect a poor breeding season in 2004 and/or worse than average winter conditions in Africa during the winter of 2004/2005. Results from Constant Effort ringing sites indicate that the latter is the more likely cause of decline between 2004 and 2005.
Red-listed species:
It is particularly important to monitor the fortunes of red-listed species of conservation concern. For nine species, BBS results reveal declines between 1994 and 2005.
Willow Tit -65% Starling -21%
Turtle Dove -45% Yellowhammer -17%
Grey Partridge -40% Skylark -13%
Corn Bunting -32% Linnet -7%
Spot Flycatcher -26%
Five red-listed species increased over the period: 1994-2005.
Grasshopper Warbler 50% Tree Sparrow 23%
Marsh Tit 33% Song Thrush 18%
Reed Bunting 30%
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