There is extensive literature on avian mortality due to collision with man‐made structures, including wind turbines, communication masts, tall buildings and windows, power lines, and fences. Many ...studies describe the consequences of bird‐strike rather than address the causes, and there is little data based on long‐term, standardized, and systematic assessments. Despite these limitations, it is apparent that bird‐strike is a significant cause of mortality. It is therefore important to understand the effects of this mortality on bird populations. The factors which determine avian collision risk are described, including location, structural attributes, such as height and the use of lighting, weather conditions, and bird morphology and behavior. The results of incidental and more systematic observations of bird‐strike due to a range of structures are presented and the implications of collision mortality for bird populations, particularly those of scarce and threatened species susceptible to collisions, are discussed. Existing measures for reducing collision mortality are described, both generally and specifically for each type of structure. It is concluded that, in some circumstances, collision mortality can adversely affect bird populations, and that greater effort is needed to derive accurate estimates of mortality levels locally, regionally, and nationally to better assess impacts on avian populations. Priority areas for future work are suggested, including further development of remote technology to monitor collisions, research into the causes of bird‐strike, and the design of new, effective mitigation measures.
The potential effects of the proposed increase in wind energy developments on birds are explored using information from studies of existing wind farms. Evidence of the four main effects, collision, ...displacement due to disturbance, barrier effects and habitat loss, is presented and discussed. The consequences of such effects may be direct mortality or more subtle changes to condition and breeding success. The requirements for assessing the impact of future developments are summarized, including relevant environmental legislation and appropriate methods for undertaking baseline surveys and post‐construction monitoring, with particular emphasis on the rapidly developing area of offshore wind farm assessments. Mitigation measures which have the potential to minimize impacts are also summarized. Finally, recent developments in the monitoring and research of wind energy impacts on birds are outlined and some areas for future work are described.
Poor reproductive success driven by nest and chick predation severely limits the population recovery of waders breeding on lowland wet grassland. Managing predation requires knowledge of the ...predators and because these can be grouped into nocturnal or diurnal hunters, detecting the timing of predation can help assess their relative impacts. Wader nest studies investigating the timing of egg predation have identified nocturnal mammals, primarily Red Foxes Vulpes vulpes, as the most important nest predators, but quantifying predator importance for highly mobile wader chicks is more difficult. Manual radiotelemetry can detect whether chicks are alive but cannot detect the time of predation, and predator identity can be determined only in the few cases where remains are recovered. As an alternative we used automatic radio tracking stations (ARTS) to constantly record the signals and predation timing of 179 radiotagged Lapwing Vanellus vanellus chicks, combining this with manual telemetry, inference about predator identity from predated remains and site‐level Fox, mustelid and avian predator activity monitoring. This approach succeeded in detecting the time of predation for 60% of the 155 chicks that were predated. Diurnal chick predation accounted for a larger number of predation events, but nocturnal predation was more intensive in terms of predation likelihood per hour. Mammalian predation during both day and night had a larger impact on chick survival than did avian predation. Raptors were primarily responsible for predation by birds and Foxes for predation by mammals, with Foxes also having a larger influence on daily chick predation rates than other predators. Chick predation increased seasonally, implying that earlier‐hatching breeding attempts are more likely to be successful. Higher Fox, raptor and mustelid activity resulted in higher proportions of chicks being predated by those predators, so quantifying the activity of those three predator groups on a site could be a quicker alternative to studying chicks when investigating which predator species to target with site‐specific predation management.
A commonly promoted view is that in the absence of driven grouse moor management in the UK uplands, land use on moorland would default to agriculture or afforestation. This forum article questions ...the orthodoxy of this thinking, discusses alternative scenarios for land use in the uplands and considers the potential effects of these on moorland‐breeding birds.
Riparian invertebrate communities are species rich, but variability in sampling methods hampers assessment of their distributions and inference of the quality of their habitats. To reduce this ...variability, a standardized, multi‐method survey protocol was recently developed. Here, riparian beetle community surveys conducted before and after the protocol's introduction were used to evaluate its effectiveness in characterizing communities and in limiting variability among surveys. Use of the standardized protocol reduced variability in sampling effort, and this had a limited effect on estimates of taxonomic richness. Surveys using the protocol captured significantly more species than surveys done before its introduction, evidencing the benefits of standardized multi‐method survey protocols. Our study highlights that standardized multi‐method survey protocols may enable identification and prioritization of sites requiring management to improve habitat quality. As such, we recommend the integration of such protocols into monitoring programmes, to enhance protection of biodiverse invertebrate communities in vulnerable riparian habitats.
Capsule: The second national survey of Twite Linaria flavirostris estimated a UK breeding population of 7831 pairs (95% confidence limits: 5829-10 137) in 2013.
Aims: To estimate the breeding ...population size of Twite in the UK and constituent countries and to calculate change since the 1999 survey.
Methods: Counts of Twite were made on three visits between May and July across a stratified random sample of 1-km squares in England, Scotland and Wales. In Northern Ireland, a complete census was made of the known range and adjacent 1-km squares with suitable habitat. Field surveys involved walking line transects 200 m apart and, in suitable nesting habitat, making 5-minute stops at 100 m intervals to scan and listen for Twite.
Results: The UK population of Twite was estimated at 7831 pairs (95% CL: 5829-10 137). This was 21% lower but not significantly different from the 1999 survey estimate. Scotland held 98% of the UK population (7640, 95% CL: 5629-9954). There were an estimated 164 pairs (95% CL: 76-297) in England, a significant decline of 72% from 1999. Estimated totals for Wales and Northern Ireland were 16 (95% CL: 10-24) and 18 pairs respectively.
Conclusion: The second national survey suggests a moderate decline in the UK Twite population since 1999 but with considerable variation between countries. Further work is required to understand the drivers of population change across breeding populations.
The conservation importance of estuaries is often measured by bird numbers, but monitoring numbers is not necessarily a reliable way of assessing changes in site quality. We used an individual-based ...model, comprised of fitness-maximising individuals, to assess the quality of the Humber estuary, UK, for 9 shorebirds; dunlinCalidris alpina, common ringed ploverCharadrius hiaticula, red knotCalidris canutus, common redshankTringa totanus, grey ploverPluvialis squatarola, black-tailed godwitLimosa limosa, bar-tailed godwitL. lapponica, Eurasian oystercatcherHaematopus ostralegusand Eurasian curlewNumenius arquata. We measured site quality as predicted overwinter survival. The model accurately predicted the observed shorebird distribution (if non-starving birds were assumed to feed on any prey or patch on which intake rate equalled or exceeded their requirements), and the diets of most species. Predicted survival rates were highest in dunlin and common ringed plovers, the smallest species, and in Eurasian oystercatchers, which consumed larger prey than the other species. Shorebird survival was most strongly influenced by the biomass densities of annelid worms, and the bivalve molluscsCerastoderma eduleandMacoma balthica. A 2 to 8% reduction in intertidal area (the magnitude expected through sea level rise and industrial developments) decreased predicted survival rates of all species except the dunlin, common ringed plover, red knot and Eurasian oystercatcher. This paper shows how an individual-based model can assess present-day site quality and predict how site quality may change in the future. The model was developed using existing data from intertidal invertebrate and bird monitoring schemes plus new intertidal invertebrate data collected over 2 winters. We believe that individual-based models are useful tools for assessing estuarine site quality.
Capsule: The 2007 national survey of the UK breeding population of Little Ringed Plovers shows a further spread into Scotland and Wales since the previous survey in 1984. In contrast, there has been ...a significant decrease in the Ringed Plover breeding population.
Aims: To provide new breeding population estimates in the UK and Great Britain for Little Ringed Plover Charadrius dubius and Ringed Plover Charadrius hiaticula in 2007 and investigate changes in breeding distribution and habitat use since 1984.
Methods: Breeding population estimates were made by combining counts of pairs from 'key sites' (2 × 2 km tetrads known to be occupied in/since 1984) and estimates of the numbers of pairs away from these sites based on stratified sampling. Survey periods for Little Ringed Plover: 15 April to 15 July, three visits; Ringed Plover: 15 April to 30 June, two visits.
Results: Population estimates, for 2007, of 1239 (95% confidence intervals: 1175-1311) pairs of Little Ringed Plover and 5291 (5106-5478) pairs of Ringed Plovers were calculated for Great Britain, with 5438 (5257-5622) pairs of Ringed Plover estimated in the UK. Counts of Ringed Plover at inland and coastal sites, covered in both 1984 and 2007, decreased by 83% and 53%, respectively. The Little Ringed Plover population has expanded in range northward and westward since 1984. Main habitats used in 2007 by Little Ringed Plover were inland gravel and sand (25.9%) and river shingle (17.8%); and, for Ringed Plover, coastal shingle and sand (38.5% and 13.7%, respectively) and machair plus associated habitats (23.8%) in the Outer Hebrides.
Conclusions: Between 1984 and 2007, the Little Ringed Plover breeding population in the UK increased considerably, expanding northward and westward, with increased use of river shingle habitats. During the same period Ringed Plover breeding numbers in the UK declined considerably in both coast and inland habitats, likely to be due to human disturbance and habitat change, respectively.
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