Greg J. Conway

Evidence for declines in populations of grassland-associated birds in marginal upland areas of Britain

Capsule We report large declines among summer populations between 1968–80 and 2000. Aim To assess changes in the status of breeding populations of birds in pastoral uplands. Methods Volunteer observers revisited 13 areas of marginal upland in Britain where Common Birds Census data were collected during 1968–80. This allowed the status of 35 bird species to be examined over about 20 years and to make a comparison between grassland-based and woodland-based species. Results For 12 species the decline in abundance was significant, particularly among passerines, such as Skylark Alauda arvensis, Wheatear Oenanthe oenanthe, Whinchat Saxicola rubetra, Yellow Wagtail Motacilla flava and Yellowhammer Emberiza citrinella, each of which declined by over 80%. Redshank Tringa totanus, Yellow Wagtail, Dipper Cinclus cinclus, Whinchat, Wheatear, Ring Ouzel Turdus torquatus and Yellowhammer were found on less than half the number of plots on which they were originally recorded. Most declining species were associated with grassland for nesting and foraging, compared to those species that increased (Wood Pigeon Columba palumbus, Pied Wagtail Motacilla alba, Carrion Crow Corvus corone, Jackdaw C. monedula and Goldfinch Carduelis carduelis) that were less specialized in their habitat requirements. Woodland or woodland edge species showed no significant change in status, suggesting that population declines among grassland species were not due to lower observer effort between recording periods. Conclusion Long-term changes to grassland ecosystems in marginal upland areas of Britain may have influenced the status of bird populations.

The status of breeding Woodlarks Lullula arborea in Britain in 2006

Capsule There have been marked increases (88%) in the breeding population and breeding range (46%) of Woodlarks in Britain between 1997 and 2006. Aims To provide an accurate assessment of the population and distribution of Woodlarks in Britain and how these have changed since a survey conducted in 1997. Methods Survey coverage included ‘core’ 1 km squares (known occupancy in 1997) and a stratified random sample, based on suitable habitat and soil type. Results A population estimate of 3064 territories was obtained, giving an increase of 88% since 1997, while the range of occupied 10 km squares had increased by 46%. The majority of territories were associated with two main habitat types; heathland (66.7%) and forestry plantation (32.4%), and farmland in the southwest (13.4%). Sandy soils held the majority of territories (80.3%). Conclusion In the UK, the Woodlark is a species of high to moderate conservation concern subject to a national Biodiversity Action Plan (BAP). This survey demonstrated that the population has increased to meet the BAP targets set in 1996 for population size and range expansions in England, and is on schedule to meet targets in Wales. The species has responded to conservation restoration projects and is highly dependent on forest management.

Distribution and abundance of birds and their habitats within the lowland farmland of Britain in winter

Capsule Farmland bird species occurred at low densities and were highly aggregated in a small proportion of available pastures, stubble fields and farmyards. Aim To document the current distribution and abundance of farmland birds and their habitats within the lowland farmland of Britain in winter. Methods Over three winters volunteer observers visited a stratified random sample of 1090 1-km squares within which they counted a suite of 30 farmland bird species and mapped agricultural habitats. Results For individual species, less than 10% of habitat patches were occupied and densities in occupied patches were low. Several differences were apparent in patterns of relative abundance compared to the 1980s. In particular marked declines of Tree Sparrow and Corn Bunting were apparent. The national distribution of cereal stubbles was localized. A large proportion of most species was found in grassland. Positive associations at the patch scale were apparent for improved grassland by invertebrate feeders and cereal and maize stubbles and farmyards, mostly by granivores. Conclusion Many farmland passerines are highly aggregated, even within particularly favoured field types. These results are consistent with winter food resources being highly localized and the need to create more food-rich patches if declines are to be reversed.

A trial of three harness attachment methods and their suitability for long-term use on Lesser Black-backed Gulls and Great Skuas

Tracking devices are useful in studying the movement and behaviour of birds throughout the year. However, the effects of device attachment must be monitored for bird welfare and the scientific veracity of information gathered. We report on a trial of three different harness types (leg-loop, body and wing) for attaching GPS devices to Lesser Black-backed Gulls Larus fuscus and of a leg-loop harness on Great Skuas Stercorarius skua. This trial evaluated the functionality of the device whilst deployed, harness retention and the effects of each harness on the birds. The leg-loop harness prevented the devices from charging, due to feathers overlapping their solar panels, and individuals of both species shed this attachment during the first breeding season. For Lesser Black-backed Gull, devices functioned properly when attached using body and wing harnesses; foraging behaviour and territory attendance of birds were similar to the findings of other studies. Despite small sample sizes, annual adult survival rates for Lesser Black-backed Gull were similar to published estimates, suggesting harnesses had no deleterious effects. The wing harness has a smaller amount of skin contact than the body harness, and a non-constricting fit that better accommodates changes in body size. The wing harness was therefore considered the most appropriate for long-term studies.

Status and distribution of European Nightjars Caprimulgus europaeus in the UK in 2004

Capsule The population of Nightjars in the UK increased by over 36% between 1992 and 2004. Aims To determine the population size and distribution of Nightjars in the UK and examine associations with forestry and heathland habitat features. Methods A volunteer survey was supported by professional cover in remote parts of Wales, and areas of Dorset and lowland Scotland. Two visits to allocated 1-km squares were made between late May and mid-July. Each surveyor recorded the locations of calling males onto maps and the occurrence of habitat categories within 50 m of each Nightjar registration. Results Observers surveyed 3264 1-km squares in 2004 and, on average, 78% of the target habitat (90% in southern England). The total number of males counted was 4131 (range 3850–4414), adjusted to 4606 (95% CL ± 913) to account for unsurveyed habitat. The adjusted total represented a 36% increase in 12 years. Nightjars were recorded in 275 10-km squares in 2004, a 2.6% increase since 1992. However, there was evidence of population decline and range contractions in northwest Britain, including north Wales, northwest England and in Scotland. In 2004, 57% of Nightjars were associated with forest plantations (similar to 1992) and 59% with heathland (slightly higher than in 1992). Conclusion National objectives for Nightjar conservation (UK Biodiversity Action Plan: UKBAP) were reached in respect of population size and stability, but the target for a 5% range increase by 2003 was not met. The continued increase in the national population is probably attributable to habitat protection, management and restoration of heathlands, and the continued availability of clear-fell/young plantations in conifer forests. Management and/or protection/restoration/re-creation of these key habitats remains critical for the long-term objectives of UKBAP. The issue of providing foraging habitats, perhaps via agri-environment schemes, is also raised.

The status of breeding WoodlarksLullula arboreain Britain in 1997

We report on the 1997 national Woodlark survey which was organized by the Royal Society for the Protection of Birds, the British Trust for Ornithology and English Nature. In 1997, between 1426 and 1552 Woodlark territories were located in Britain. There has been a considerable increase in the population since the only previous national survey, in 1986, when approximately 250 territories were found. The five regions of population that were apparent in 1986 all showed major increases, in particular in Breckland and the Suffolk Sandlings. Over 85% of territories occurred on heathland or within forest plantations. The ratio varied between regions: plantations were more commonly used in the north and east whereas more Woodlarks utilized heathland in the south. Woodlarks in Devon bred almost exclusively on farmland. More than three-quarters of the forest population was found in young plantations, particularly in stands of two and three year old trees. Most Woodlark territories were located on sandy soils, with nearly 70% specifically on acid sandy soils. Reasons for the observed increase and range expansion are discussed, as are the implications of habitat management practices.

The impact of changing habitat availability on population trends of woodland birds associated with early successional plantation woodland

Capsule Trends in young woodland availability influenced population trends and abundance of Tree Pipit and Lesser Redpoll, but not 10-km square occupancy. Aims To investigate whether changes in availability of young woodland could have driven population change, and trends in abundance and occupancy, of declining Tree Pipit and Lesser Redpoll populations in Britain. Methods Modelling approaches used annual population indices and woodland planting statistics. Abundance and occupancy change between two bird atlases were examined in relation to changes in woodland availability from two woodland inventories. Results English declines were strongly associated with decreases in young coniferous woodland availability and less strongly with increases in young broadleaved woodland. Abundance was related to the area of young woodland in corresponding 10-km squares. Young woodland availability declined between forest inventories and species occupancy maintained in 10-km squares with more young woodland; however squares that showed retention or increases in occupancy showed higher reductions in woodland. Conclusion We suggest declining availability of young coniferous woodland contributed to Tree Pipit and Lesser Redpoll population trends in England. Although likely to be the case in Scotland and Wales, the lack of sufficient temporal data inhibited our ability to test this properly. This work suggests that woodland availability was not the primary driver of Tree Pipit or Lesser Redpoll population trends.

Breeding bird communities in the upland margins (ffridd) of Wales in the mid-1980s

Capsule The bird communities in the Welsh marginal uplands were frequently distinct from those of adjacent habitats and consisted of heterogeneous mixtures of species strongly influenced by vegetation composition and land-use. Aims To provide a unique description of the influence of vegetation, altitude and regional position on the bird communities of upland margins and to create a baseline against which future changes in these communities may be assessed. Methods Survey data collected at 120 sites in 1985–87 were used to identify broad relationships between habitat and bird communities. This was complemented by habitat descriptions made at exact locations occupied by individual birds. Results Bird communities in Bracken-dominated sites, especially those with relatively high numbers of scattered trees and bushes, held more species than sites dominated by grassland and other moorland vegetation. Relationships between species and habitat were broadly consistent at both the scale of whole sites and the scale of patches occupied by individual birds. Abundance of scattered trees and bushes was important for a diverse range of passerines; extent of Gorse Ulex spp. scrub was important for several species. Geographical location and topography appeared to have secondary effects on bird communities relative to those of vegetation composition. Conclusions The Welsh marginal uplands hold diverse bird communities, strongly affected by local vegetation composition and usually different from those of adjacent moorland, woodland and farmland. Tree Pipit Anthus trivialis, Whinchat Saxicola rubetra, Linnet Carduelis cannabina and Yellowhammer Emberiza citrinella were among the species likely to be more abundant in the upland margins than in adjacent habitats. There is a need to assess whether these communities have changed since the mid-1980s, especially in relation to high sheep grazing pressure. However, agricultural abandonment of marginal areas may occur in the future which could eventually reduce habitat availability for several bird species and reduce avian diversity in the Welsh uplands.

Current status and recent trend of the Eurasian Woodcock Scolopax rusticola as a breeding bird in Britain

Capsule The breeding Woodcock population in Britain in 2013 was estimated at 55 241 males (95% CL: 41 806–69 004), suggesting a large-scale decline that is supported by 2 additional sources of data. Aims To provide an updated estimate of the size of Britains breeding Woodcock population, measure recent trends and identify spatial patterns of change. Methods Displaying male Woodcock were surveyed at a stratified sample of 834 randomly selected sites. Population estimates were compared with a baseline survey conducted in 2003 and the trend with data from annual Woodcock counts (2003–13) and Bird Atlas 2007–11. Results Woodcock were estimated to be present at 22% of 1 × 1 km squares containing ≥10 ha of woodland, compared to 35% in 2003. The British population estimate fell by 29% between 2003 and 2013. The Atlas suggests that presence at the 10 × 10 km scale has declined by 56% between 1970 and 2010. Both data sources suggest regional variation in the rate of decline, with losses greatest in the West and South. Conclusion The Woodcocks population size and breeding range appear to be declining severely across Britain. Regional variation in the rate of decline might be explained by the distribution of large continuous woodlands.

Bird ringing in Britain and Ireland in 2009

This is the 73rd annual report of the British Trust for Ornithologys Ringing Scheme, covering data received and work carried out in 2009. Much of the research carried out during the year looked at ways to improve the analysis of ringing data to understand population change. This included producing survival rates from the Constant Effort Sites (CES) scheme for the first time and further developing methods of analysing our demographic data sets in an integrated manner. Research was also undertaken on the biometric data to investigate how individual condition responds to long‐term environmental change. CES data suggested that the low productivity in 2007 and 2008, combined with one of the coldest winters since 1995/96 for residents, contributed to reduced adult numbers in 2009 in many species. There were significant decreases in Wren Troglodytes troglodytes, Sedge Warbler Acrocephalus schoenobaenus, Reed Warbler A. scirpaceus, Blackcap Sylvia atricapilla, Lesser Whitethroat S. curruca, Willow Warbler Phylloscopus trochilus, Long‐tailed Tit Aegithalos caudatus, Blue Tit Cyanistes caeruleus, Great Tit Parus major, Treecreeper Certhia familiaris, Chaffinch Fringilla coelebs, Greenfinch Carduelis chloris and Reed Bunting Emberiza schoeniclus. However, a good breeding season, for both residents and migrants, resulted in significantly higher productivity for 15 species, but significantly lower for Willow Tit Poecile montana, compared to the long‐term mean (1983–2007). Data for 104 Retrapping Adults for Survival studies were submitted, covering 39 species, three quarters of which are Birds of Conservation Concern. The total number of birds ringed (935,867) was the highest ever recorded, and was over 10% higher than the mean of the previous five years. However, the total number of pulli ringed in 2009 (179,712) was only 5% higher than the preceding five‐year mean, while that of fully grown birds (756,155) was over 13% higher. The recovery total (14,643) was also high. However, this is partly due to changes in the way that records of colour‐ringed and other specially marked birds are stored. The number of recoveries of foreign‐ringed birds (1,314) was higher than the mean of the preceding five years, although this figure is influenced by varying response times of different ringing schemes. Recovery details for 250 individual birds are given in the final section of the report. They include movements that confirm suspected or known migration patterns, unexpected movements and longevity records.