The marine environment is increasingly subject to pressure from human activities, with knock on effects for wildlife. Many studies over recent years have attempted to assess the risk of offshore wind turbines to seabirds. Birds might be injured or killed through collision with turbines or associated structures, they might be displaced from an area they previously used, and they could suffer energetic costs of bypassing a wind farm instead of commuting straight through. BTO has been using long-lived GPS tags to conduct a multi-year study into the possible effects of offshore wind farms on Lesser Black-backed Gulls. Results show that birds’ use of the environment varies between individuals, throughout the breeding season and over the years. This information is essential to estimate the magnitude of risks posed by offshore wind developments to seabird populations as accurately as possible. Wind farm use varies BTO scientists, led by Chris Thaxter, tracked twenty-five Lesser Black-backed Gulls breeding at Orford Ness on the Suffolk coast, in three consecutive summers. The study found that gulls visited areas where offshore wind farm developments are proposed significantly more often in some years than in others. In every year, birds spent more time in wind farms zones when their chicks were young than at other times in the breeding season. Males also spent more time in these zones than females later on in the breeding season, when chicks were growing bigger and more independent. Such seasonal variation could be mediated by changes in the availability of prey preferred by adults, and by changes in the nutritional requirements of their offspring at different stages in their development. Individual variation could be determined by dietary specialisations. These results indicate just how varied individual seabirds can be in their behaviour, and highlight the value of long-term tracking data sets in estimating potential impacts of offshore wind farms on seabird populations. Offshore wind farms are a key part of the UK Government’s plan to obtain 15% of the country’s energy from renewable sources by 2020. It is therefore important to properly assess and quantify the impact that such developments could have on marine wildlife and habitats.

Published statistics on trends in raptor populations in Scotland currently use data from three national bird atlases, State of the UK Birds assessments, national BTO/JNCC/RSPB Breeding Bird Surveys (BBS) and species surveys undertaken through SCARABBS (Statutory Conservation Agencies and RSPB Breeding Bird Survey). This report considers the prospects for producing more detailed Scotland-wide and regional trends for breeding raptors. The report focuses on assessments of the suitability of data and methods for producing trends at a range of spatial scales, from area based - e.g. Natural Heritage Zones - to the whole of Scotland, and for breeding numbers and appropriate breeding parameters - e.g. proportion of pairs fledging young or the number of young fledged. The report meets three objectives: (i) produce and report trends in breeding numbers and productivity for the raptor species in Scotland at a range of spatial scales; (ii) evaluate the suitability of the existing schemes that are in place which may contribute to the monitoring of raptors (particularly EC Birds Directive Annex 1 species); and (iii) scope methods for producing a robust indicator or indicators of Scottish raptor populations, with the most appropriate indicator(s) dependent on end-user requirements. The report draws largely on data collected under the auspices of the Scottish Raptor Monitoring Scheme (SRMS). This was established in 2002 to improve partnership working between organisations involved in raptor monitoring in Scotland. It has eight partners, is chaired by SNH, and currently focuses on the annual monitoring of the abundance, distribution and breeding success of diurnal birds of prey and owls native to Scotland. The data are primarily from the SRMS for the period 2003-2009, supplemented by other sources where appropriate. Main findings Estimates of trends in numbers and/or breeding productivity, at least at the scale of individual study areas, can be calculated for 13 species of breeding raptors in Scotland. The most appropriate parameter for measuring breeding success for raptors, from the available data, is the number of fledglings produced per successful pair. COMMISSIONED REPORT Summary ii Data were sufficient to produce national, Natural Heritage Zone and area trends in breeding numbers and breeding productivity for two species – red kite and white-tailed eagle. Both show steady increases in breeding numbers since they were re-introduced. For seven species with substantial annual monitoring coverage across Scotland (hen harrier, northern goshawk, common buzzard, golden eagle, merlin, peregrine falcon and barn owl), provisional area based trends in breeding numbers were produced. For these species, there is high potential to produce rigorous area-based trends in breeding success, and potentially also full national (Scottish) trends, in both breeding numbers and breeding success. For four other species (Eurasian sparrowhawk, common kestrel, tawny owl and common raven), partial trend information is available from study areas or from the BBS. However, this is not considered sufficient to report rigorous national trends, without further validation work or additional data collection. A further four species (European honey buzzard, black kite, Eurasian marsh harrier and Eurasian hobby) are too rare as breeding birds in Scotland to enable their trends to be calculated. Finally, for long-eared owls and short-eared owls, there is currently insufficient annual monitoring coverage to generate trends. Recommended enhancements to information collection under the SRMS include: submission of six-figure grid references for all breeding ranges; routine collection of information on survey coverage/effort, visit dates, and nest contents at each visit; and improved (on-line) software for standardized data entry. Given the data available, we cannot produce a national indicator for breeding raptors in Scotland. Once representative national trends are available for a broader suite of Scottish raptors, however, a national indicator of breeding raptor numbers is feasible, and should be considered further.