Spatial and temporal distribution of shorebirds: predicting the effects of habitat change on the Forth Estuary.

First paragraph: Overview One of the many threats to coastal shorebirds globally is the loss or degradation of estuarine intertidal mudflats, a habitat that supports large concentrations of birds both on passage and throughout the winter months. British estuaries comprise 28% of the entire estuarine area of the Atlantic and North Sea coastal states (Atkinson et al. 2001), more than any other European country. Because of this, many UK estuaries are of great importance in both a European and international context for wintering birds (Pollitt et al. 2000). Furthermore, Britain’s estuaries can be particularly important during periods of severe cold weather in continental Europe (Norman & Coffey 1994), when there may be influxes of waterfowl from other coastal regions or inland areas. Some sites also act as cold weather refuges where parts of the estuarine system freeze more slowly than other nearby coastal and inland wetlands and so can provide feeding habitat when other sites are unavailable. Habitat change may not always mean habitat loss, even though large intertidal areas have been removed via landclaim (Evans 1979, McLusky et al. 1992) and engineering works (Schekkerman et al. 1994) or are threatened by the gradual rise in sea level (Austin et al. 2001). Determining the effects of habitat deterioration on shorebirds is often more difficult to predict (Sutherland 1998b) as, although the habitat remains intact, it may reduced in quality due to pollution events (McLusky 1982, McLusky & Martins 1998) or disturbance (Burger 1994, Burton 1996, West et al. 2002). The consequences of habitat change on estuaries are so potentially threatening to shorebird populations that programs of managed realignment (Burd 1995) have been introduced at some sites in order to mitigate such alteration (Dixon et al. 1998, French 1999, Hackney 2000). Such management activity involves the breaching of existing sea walls to allow the land behind to gradually return to estuarine habitat. It has been shown that invertebrates will colonise suitable intertidal habitats and that birds are quick to adapt to such new habitats (Evans et al. 1998)

87Sr/86Sr isotope fingerprinting of Scottish and Icelandic migratory shorebirds

Biosphere Sr isotope composition data from Iceland and Scotland suggest that terrestrially feeding birds from these two countries will have significantly different 87Sr/86Sr isotope composition in their tissues. The aim of this study is to test if these differences can be measured within the bone and feather of migratory wading birds, who feed terrestrially as juveniles, thus providing a provenance tool for these birds. The study shows that birds can be distinguished on the basis of the Sr isotope composition of their bone. The field for Icelandic birds is defined by data from juvenile common redshank (Tringa totanus) and whimbrel (Numenius phaeopus) which give 0.7056 ± 0.0012, (2r, n = 7). The majority of Scottish birds in this study are from coastal regions and have a signature close to that of seawater of 0.7095 ± 0.0006 (2r, n = 9). The Sr ratios in the body tissue of these two populations of all Icelandic and Scottish adult and juvenile birds analysed are significantly different (p < 0.001, at 95% confidence limits). Scottish birds from inland areas such as a common snipe (Gallinago gallinago) record 87Sr/86Sr values as high as 0.7194 which reflect their non-marine diet. Icelandic redshank (Tringa totanus robusta) that have flown to Scotland and returned to Iceland show the effect of the Scottish contribution to their diet with elevated values of 0.7086 ± 0.0004, (2r, n = 6). Redshank found in Scotland that cannot be classified on the basis biometric analysis are shown to be of Icelandic origin and analysis of the primary feathers from two birds demonstrates that isotope variation between feathers could be used to track changes in diet related to the timing of individual feather growth

The distribution of breeding birds around upland wind farms

Summary 1. There is an urgent need for climate change mitigation, of which the promotion of renewable energy, such as from wind farms, is an important component. Birds are expected to be sensitive to wind farms, although effects vary between sites and species. Using data from 12 upland wind farms in the UK, we examine whether there is reduced occurrence of breeding birds close to wind farm infrastructure (turbines, access tracks and overhead transmission lines). To our knowledge, this is the first such multi-site comparison examining wind farm effects on the distribution of breeding birds. 2. Bird distribution was assessed using regular surveys during the breeding season. We took a conservative analytical approach, with bird occurrence modelled as a function of habitat, before examining the additional effects of wind farm proximity. 3. Seven of the 12 species studied exhibited significantly lower frequencies of occurrence close to the turbines, after accounting for habitat variation, with equivocal evidence of turbine avoidance in a further two. No species were more likely to occur close to the turbines. There was no evidence that raptors altered flight height close to turbines. Turbines were avoided more strongly than tracks, whilst there was no evidence for consistent avoidance of overhead transmission lines connecting sites to the national grid. 4. Levels of turbine avoidance suggest breeding bird densities may be reduced within a 500-m buffer of the turbines by 15-53%, with buzzard Buteo buteo, hen harrier Circus cyaneus, golden plover Pluvialis apricaria, snipe Gallinago gallinago, curlew Numenius arquata and wheatear Oenanthe oenanthe most affected. 5. Despite being a correlative study, with potential for Type I error, we failed to detect any systematic bias in our likelihood of detecting significant effects. 6. Synthesis and applications. This provides the first evidence for consistent and significant effects of wind farms on a range of upland bird species, emphasizing the need for a strategic approach to ensure such development avoids areas with high densities of potentially vulnerable species. Our results reduce the uncertainty over the magnitude of such effects, and will improve future environmental impacts assessments

Barriers to movement: impacts of wind farms on migrating birds

Advances in technology and engineering are enhancing the contribution that wind power makes to renewable energy generation. Wind farms, both operational and in planning, can be expected to impact negatively on wildlife populations, particularly birds. We propose a novel approach to assess the impacts through the energetic costs of avoidance behaviour for a long-distance, migratory seaduck. Flight trajectories were recorded using surveillance radar at a Danish offshore wind farm with emphasis placed on the 200 000+ migrating common eiders that pass through the area annually. Minimum distance to wind farm and curvature of trajectories were compared pre- and post-construction. Additional costs of the avoidance response were estimated using an avian energetic model. The curvature of eider trajectories was greatest post-construction and within 500 m of the wind farm, with a median curvature significantly greater than pre-construction, suggesting that the birds adjusted their flight paths in the presence of the wind farm. Additional distance travelled as a consequence of the wind farm's presence was ca. 500 m and trivial compared with the total costs of a migration episode of 1400 km. However, construction of further wind farms along the migration route could have cumulative effects on the population, especially when considered in combination with other human actions