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Habitats Regulations Appraisal of Draft Plan for Offshore Wind Energy in Scottish Territorial Waters: Appropriate Assessment Information Review


Appendix D. Seabird Foraging and Migratory Baseline Review for the Draft OWE Plan HRA

D1. Introduction

To inform the HRA for the Draft OWE Plan HRA, this appendix reviews what is known about the foraging behaviour and migration routes of coastal and offshore bird colonies (overwintering and breeding populations).

D2. Seabird Foraging Behaviour

The distances over which waterbirds forage offshore has been initially reviewed to inform both the screening and assessment phases for the HRA. For this review, information was drawn upon from a range of studies including the review of seabird foraging distances that was undertaken by BTO (Roos et al 2009) as part of the PFSAHRA work ( ABPmer, 2010), and reports reviewed therein including; Dillon et al., (2009), Furness and Tasker (2000), Hamer et al., (2000, 2001, 2007), Suryan et al. (2000), Thaxter et al. (2010) and Wanless et al. (1990, 1991, 1998). The online BirdLife International (2010) seabird foraging database 21 was also reviewed along with a number of other papers including; BirdLife International (2000), Fenny & Walls (2009) and Ratcliffe et al. (2000) and the maximum foraging ranges for each species were identified. The reference section in each of the retrieved papers was also scanned to make sure that no relevant key studies were missed. Where possible the methodology used in each study was identified, as different approaches may have intrinsic problems. The results are presented as a summary table showing maximum foraging ranges for each species along with text summaries for each of the species that forage over the greatest distances offshore.

This summary review is designed to provide guidance of the sites and species that need to be considered during the screening and assessment work for this Plan-level HRA as well as for future project-level HRAs. Focus is on seabirds foraging offshore as opposed to species (especially waders) that forage in intertidal areas. In summary the factors that might affect offshore seabird foraging range distances include:

  • Spatial variation in food abundance (including anthropogenic factors such as fishing vessels);
  • The risk of predation/kleptoparasitism by other bird species;
  • The importance of nest attending to incubate eggs and protect nest from predators; and
  • Weather and climatological factors (British Trust for Ornithology (Roos et al., 2009).

The distances that are typically covered by seabirds foraging offshore varies greatly between species (see Table D1) and our research and understanding of their foraging behaviour has increased in recent years. As part of this research increasingly novel techniques and technologies are being developed to track birds and to investigate foraging behaviour in particular. Over relatively short distances and timescales transects, ship-based surveys and radio-telemetry have been used (Perrow et al., 2006; Wilson et al., 2009). To track birds over considerably greater distances and over larger time frames GPS data loggers are deployed, however they necessitate recovery of the data logger to extract information, or close approach for remote data download (Guilford et al., 2008). The greatest opportunity to follow birds over potentially huge distances and over extended time periods comes from satellite tracking, but at present this is only useful for birds of large body size such as northern gannet (Hamer et al., 2000; 2001; 2007). Radar is one of the more powerful tools available to describe the movement of birds in three-dimensional space and its use has been long-established and well described (Desholm et al., 2004). Relationships between foraging trip duration and, respectively, maximum distance from the colony and total trip distance have also been estimated for many bird species to determine foraging behaviour (Hamer et al., 2007).

Table D1. Foraging ranges of breeding seabirds (from breeding colonies) taken from a number of literature sources

Table D1. Foraging ranges of breeding seabirds (from breeding colonies) taken from a number of literature sources

Although foraging distances are relatively well understood, little is known about foraging direction. Hamer et al. (2007) produced a study into the foraging behaviour of gannets in the North Sea and found that they tended to forage repeatedly over a narrow range of bearings, despite marked annual variations in foraging ranges and trip durations (Image D1). Hamer et al. (2001) also recorded gannets foraging repeatedly over a narrow range of bearings from their breeding location at Bass Rock. This study also observed gannets switching to a separate range of bearings in a markedly different direction from the breeding colony, providing strong evidence that on subsequent foraging trips individuals remembered the directions to feeding sites (Hamer et al., 2007). However, conversely to this, birds at a much smaller site in the Celtic Sea (Great Saltee) did not show this pattern (Hamer et al., 2001). Hamer et al. (2007) concluded that these differences in the consistency of foraging locations were related mainly to difference in the spatial and temporal predictability of prey resources in the North Sea and Celtic Sea.

Image D1. Representation of one of the maps produced in Hamer et al. (2007) indicating the foraging locations of Northern Gannet from Bass Rock in 2002

Image D1. Representation of one of the maps produced in Hamer et al. (2007) indicating the foraging locations of Northern Gannet from Bass Rock in 2002

The review undertaken by BTO as part of the PFSAHRA work (Roos et al., 2009 in ABPmer, 2010) identified the maximum distances seabirds foraged based on a review of studies including RSPB (2000), Furness & Tasker (2000) and Thaxter et al. (2010) along with the UK Seabirds at Sea data ( JNCC 2009). This study found that most birds typically forage within 100km of breeding site with the exception of the following species (for which the foraging distances are highlighted in brackets): Razorbill (150km); Guillemot (123km); Puffin (137km); Fulmar (245km); Gannet (540km); Manx Shearwater (330km). Following a further review of the available information and, based on advice from SNH, appendix has included relevant information from the BirdLife International (2010) seabird foraging database on maximum foraging distances for key species (see Table D1). Using the information, as set out in Table D1, the species with maximum foraging distances greater than 100km include; (maximum foraging distances are highlighted in brackets)

  • Atlantic Puffin (200km);
  • Black-legged Kittiwake (200km);
  • Common Guillemot (200km);
  • Common Scoter (200km);
  • Manx Shearwater (400km);
  • Northern Fulmar (664km);
  • Northern Gannet (640km); and
  • Razorbill (150km).

In addition to the above sources of information we note that further details about the maximum foraging distances can be obtained from the Interreg FAME project (Aedán Smith, RSPB Pers. Comm.) 22. Fieldwork for this project in 2010 recorded the following foraging ranges using high-resolution GPS tags:

  • Fulmar 506km
  • Kittiwake 231km
  • Razorbill 213km

The distances found for Kittiwake and Razorbill are greater than those referenced above. For this review of foraging distances and the HRA screening work ABPmer, with advice from SNH and JNCC, focused on using the data in the Birdlife international foraging database to identify the maximum foraging distances. However, other studies such as this FAME project will need to be re-considered further as part of future project-level HRAs to ensure that proposed developments do not have an adverse effect on forging seabirds.

D2.1 Species Review

Those species listed-above which forage over long distances have been included in more detail in the following review. These species are reviewed particularly because the could forage within the short of medium term option areas even though the designated European/Ramsar sites for which they are a qualifying interest features lies at some distance away. In particular, because they forage over distances of greater than 100km, the designated sites for which they are feature could lie outside the 100km boundary area that was used to inform the screening of the AA. In addition, the Arctic Skua, Common Eider and Great Skua which have relatively lager foraging distances (100km) have also been reviewed (although where these are qualifying features for a designated they would be automatically screened in using the 100km boundary approach adopted). These reviews of foraging distances for individual species draw predominantly upon the information contained within the online BirdLife International (2010) seabird foraging database.

D2.1.1 Arctic Skua Stercorarius parasiticus

There is little detailed information on the foraging ranges of Arctic Skuas, but since the majority of breeding birds in the north-east Atlantic and non-breeders in other regions are kleptoparasites (a form of feeding in which one animal takes prey or other food from another), their foraging distributions are largely determined by opportunities for kleptoparasitism, most of which takes place close to host colonies (BirdLife International, 2010).

Studies by Furness (1978) and Phillips (1995) observed very few patrolling Arctic Skuas on the island of Foula, Shetland, more than 2km from the coast, and pursuit of hosts appeared to be initiated within 1km of two principal sites, both of which were located within less than 2-3km of all Skua territories on the island. Briggs et al., (1987) however reported Arctic Skuas occasionally as far as 75km off the California coast, although most were found within 15km or in estuaries, often with colonies of terns or small gulls (Stallcup, 1990).

For the purposes of this draft OWE Plan HRA, the maximum quoted foraging range of 100km has been assumed for Arctic Skua (see Table D1) as quoted by BirdLife International (2010).

D2.1.2 Atlantic Puffin

There are few studies containing direct information on the foraging range of Atlantic Puffins. An individual Puffin breeding on Isle of May, Scotland, was studied during the breeding season 1987 using a radio transmitter. Of the trips made 64% were within 2km, 7% between 2-10km and 29% more than 10km (Wanless et al., 1990). Transect surveys around the Isle of May also found that Puffins were most common close to the colony but on some occasions birds occurred at a sandbank, the Wee Bankie, 40km away.

After a crash of herring stocks near to the colony, Puffins at Røst Island, Norway were observed to travel at least 137km to fishing grounds (Anker-Nilssen and Lorentsen, 1990). Another study (Pearson, 1968) also estimated that Puffins breeding on the Farne Islands could forage a maximum distance of 137km from the colony. On the basis of average trip durations at UK colonies (various sources) and flight speeds of 82km/h one study suggested a potential range of over 200km from Great Island, Newfoundland, Canada (Bradstreet & Brown, 1985). Although this method of calculating foraging range has been criticised as being inaccurate and may be an overestimate, the conservative estimate by Bradstreet & Brown (1985) of 200km has been given as a maximum foraging range for Atlantic Puffin. Therefore the purposes of this draft OWE Plan HRA, this maximum quoted foraging range has been assumed for Puffin (see Table D1) as also quoted by BirdLife International (2010).

D2.1.3 Black-legged Kittiwake Rissa tridactyla

The foraging range of Kittiwakes has been widely studied using a range of techniques. Radio tracked Kittiwakes were found to forage a maximum of 62km in Prince William Sound, Alaska (Ostrand et al., 1998), and over 40km at Sumburgh Head, Scotland (Hamer et al., 1993). Kittiwakes have also been calculated to forage 55km from a colony at Farne Island based on mean trip duration of 158 min during chick-rearing, and a flight speed of 48km/h (Pearson, 1968). A study at Prince Leopold Island, Canada used aerial surveys of Kittiwake densities. They found that during chick-rearing Kittiwakes were most abundant within 48km of the colony, although some large concentrations were found up to twice that distance away (Nettleship & Gaston, 1978). High concentrations of Kittiwakes have also been observed 20-30km from the nearest colonies at Caithness, Scotland (Mudge & Crooke, 1986) and at 30km from a colony on the Isle of May (Wanless et al., 1998). Both Daunt et al., (2002) and Humphreys et al., (2006) recorded that the maximum foraging range for Kittiwakes on the Isle of May was 83km.

Foraging distances have shown to be dependent on prey availability. Suryan et al., (2000) found that increased foraging distance at two separate colonies at Prince William Sound, Alaska were associated with low prey abundance. In years where herring dominated diets mean distance to the farthest feeding location was 40km, whereas when Kittiwakes consumed other species foraging distance increased to 60km, with the maximum recorded foraging range being 120km (Suryan et al., 2000).

For the purposes of this draft OWE Plan HRA, the maximum quoted foraging range of 200km has been assumed for Kittiwake (see Table D1) as quoted by BirdLife International (2010).

D2.1.4 Common Eider

Two studies observed Common Eider foraging very close to shore, within 50m, in southwest Greenland (Merkel & Mosbech, 2008) and southeast Newfoundland (Goudie & Ankney, 1988). Durinck et al., (1994) and Petersen et al., (2003) studied Common Eider at Kattegat, Denmark, recording large concentrations 40km and 20km offshore respectively. Common Eider has also been observed much further offshore. Merkel et al., (2006) fitted satellite transmitters to Common Eiders and observed that wintering birds in southwest Greenland had a mean home range size of 68km. Cooch (1965) however suggested the maximum foraging range used by nesting females could be over 80km and Goudie et al., (2000) reported Common Eiders flew 50-100km to feed. Although this maximum foraging range has been observed in North America it has been taken as a precautionary estimate of maximum foraging range for this study. For the purposes of this draft OWE Plan HRA, the maximum quoted foraging range of 100km has been assumed for Common Eider (see Table D1) as also quoted by BirdLife International (2010).

D2.1.5 Common Guillemot Uria aalge

The foraging behaviour of auks, including foraging range, has been studied in depth for many years throughout the UK and North America using a variety of different methods. Numerous studies have taken place in Scotland, in particular at the Isle of May (Tasker et al., 1987, Thaxter et al., 2009; 2010, Wanless et al., 1990; 1998). The most recent of these surveys by Thaxter et al., used bird-borne compass loggers to study foraging ranges. Thaxter et al., (2009) found that of 19 Common Guillemots breeding on the Isle of May (28 trips from 11 males plus 29 trips from 8 females), the maximum range for males was 14.4 ± 6.6km and 7.9 ± 5.3km for females. During a similar study Thaxter et al., (2010) observed 61 Guillemots travel an average distance of 34.5km/trip (±29.8), with the maximum observed distance from the colony being 14.1km (±12.2).

A study from North America (Cairns et al., 1987), used data loggers in combination with recorded flight speed, to estimate that the longest foraging range for Guillemots was 123km during incubation and 80km during chick rearing. However, median foraging ranges were much smaller.

For the purposes of this draft OWEHRA Plan, the maximum quoted foraging range of 200km has been assumed for Common Guillemot (see Table D1) as quoted by BirdLife International (2010).

D2.1.6 Common Scoter

A number of studies into the foraging range of Common Scoter have taken place off the Welsh coast. At Llanfairfechan concentrations of birds were found between 1-4km offshore and at Red Wharf Bay the majority of birds were more than 3km offshore (Kaiser, 2004). In Conwy Bay birds were also recorded 3-4km offshore (Kaiser et al., 2006). However, studies over Lithuania and Estonia, using radar observations, recorded massive summer movements of Scoter with birds travelling 20-30km from the shore over the Baltic Sea (Kumari, 1979; Zalakevicius & Jacoby, 1992).

Based on an estimate by BirdLife International (2010), the maximum foraging range of Common Scoter has been given in Table D1 as 200km and this value has been used for the purposes of this draft OWE Plan HRA.

D2.1.7 Great Skua Catharacta Skua

As with the Arctic Skua, there is little detailed information on the foraging ranges of Great Skua. A number of studies (Votier et al., 2004; 2006, Wood, 1989) have found that Great Skuas feeding on seabird prey tend to have small foraging ranges confined to the coastline of their breeding colonies, and seldom move more than 2km from their nest site (Votier et al., 2004).

In contrast Skuas feeding on fish will often travel long distances to find them at sea. The study by Votier et al., (2004) used radio-transmitters to track Great Skuas at Hermaness. Those feeding on discards often flew several tens of km to fishing fleets off Muckle Flugga. Smith & Jones (2006) indirectly estimated a foraging range of 31km for Great Skua following the recovery of a bird ring from a Razorbill chick in a Skua pellet.

During the early-mid 1970s the estimated maximum foraging range of breeding Great Skua on Foula was 14km, based on the mean length of foraging trips of around 35minutes (Furness, 1978). However, probably due to a reflection of changes in diet, foraging trip durations have become far longer in more recent years. Throughout the 1994 and 1995 breeding seasons, feeding trips were taking in excess of one hour, with a median length during chick-rearing of more than 3.5 hrs, and some breeding adults could easily have been ranging much further afield, perhaps 50-100km or more (BirdLife International, 2010). Although larger than other records of foraging range, for the purposes of this draft OWE Plan HRA, the maximum quoted foraging range of 100km has been assumed for Great Skua (see Table D1) as quoted by BirdLife International (2010).

D2.1.8 Manx Shearwater Puffinus puffinus

Guilford et al., (2008) made an interesting study of foraging behaviour of Manx Shearwaters from Skomer Island, Wales using GPS tags attached to individuals. These birds were tracked flying north to the Mull of Galloway to feed, travelling a straight-line distance of more than 330km each way. Another study by Brooke (1990) estimated that Manx Shearwater could travel as far as 360km from the colony during chick rearing, based on an absence of two days, a flight speed of 45km/hr and 8hr flying in each direction (although the values chosen for the time spent flying were arbitrary). A conservative estimate of 400km, as set out in Table D1, has been given as maximum foraging range for Manx Shearwater, based on the assessment by BirdLife International (2010). This value has been used for the draft OWE Plan HRA.

D2.1.9 Northern Fulmar Fulmarus glacialis

Most of the information on Fulmar foraging ranges is based on trip durations, which given the many assumptions involved in calculating ranges from such data, should be viewed as maxima. Foraging trip durations for Fulmars are variable among sites and years.

Hamer et al., (1997) studied populations of Fulmars on St Kilda, Outer Hebrides and Foula (Shetland). They estimated that the maximum foraging trip distances would be 245km for birds on St Kilda and 122km for Fulmars on Foula (Hamer et al., 1997). A study in Scotland also trapped live one breeding adult 460km from its nest site (Dunnet & Ollason, 1982) and in north east Greenland satellite tracked radio-tagged adults foraged 40-200km during incubation and chick-rearing, with failed breeders travelling more than 300km (Falk & Møller, 1995). Other authorities have given potential maxima of foraging radii of between 140km and 750km, assuming linear flight and negligible time spent on the water. While these will be overestimates of the radii travelled (as Fulmars deviate from straight line flight and spend time on the water feeding and resting, and may make overnight visits to feed chicks, which are often not recorded), they demonstrate that Fulmars have time to travel very long distances during foraging trips and could easily exceed a 100km radius from the colony (BirdLife International, 2010). As set out in Table D1, a maximum foraging range of 664km has been given for Northern Fulmar based on BirdLife International (2010) data. This value has been used for the draft OWE Plan HRA.

D2.1.10 Northern Gannet Morus bassanus

Gannets breeding on Bass Rock, Scotland have been studied in detail using GPS transmitters (Hamer et al., 2000; 2001; 2006; 2009). Hamer et al., (2001) recorded a maximum foraging range of 540km from Gannets at Bass Rock, Wanless et al., (1998) recorded feeding at sites 33km (Wee Bankie) and 20km (Fife Ness) away whilst a more recent study (field work undertaken in July and August 2003) by Hamer et al., (2009) found the mean foraging range per trip by Gannets was 155km, with a maximum of 276km recorded.

Northern Gannets at Great Saltee, Ireland were recorded travelling a maximum of 240km (Hamer et al., 2001) and 293km (Hamer et al., 2006) to foraging grounds. At Rouzic, France a breeding colony of Gannets were found to have a mean foraging range of 100km, with a maximum of 176km (Grémillet et al., 2006). Large feeding flocks of gannets were also recorded, using ship-based transects around St Kilda, within only a few km of Boreray whilst several smaller groups were seen 40km away (at the Whale Rock Bank) (Leaper et al., 1988). A study by Tasker et al., (1985) also observed a maximum foraging range of gannets to be 150km from Noss, UK, however the majority were seen within 37km. Nelson (1978) estimated a range of 320 to 480km for breeding gannets from a colony, based on observed trip durations and assuming continuous flight at 65 to 80km/h.

A study by Lewis et al., 2001 suggests that foraging range increases significantly for Northern Gannets with increasing colony size, probably as a result of intra-specific competition causing birds to forage further away from the colony during years with higher numbers of breeding Gannets (Lewis et al., 2001). Based on an estimate by BirdLife International (2010) the maximum foraging range of Northern Gannet has been given in Table D1 as 640km. This value has been used for the draft OWE Plan HRA.

D2.1.11 Razorbill Alca torda

A study by Webb et al., (1985) at Flamborough Head found that maximum densities of Razorbill were recorded foraging at 26-28km from colonies, although large numbers were also seen from the coast within 1km from the colony. A more recent study by Thaxter et al., (2010) supports this conclusion. Using bird-borne data loggers to record foraging trips made by 14 Razorbills from the Isle of May breeding colony, they found that of the 76 foraging trips made just under half were within 10km of the coast, with the remainder of trips to areas 30-40km offshore, with the longest foraging trip being approximately 60km. Gaston and Jones (1998, cited in Thaxter et al., 2010) however, have reported Razorbills carrying prey more than 150km from the nearest breeding colony. Although higher than other estimates of foraging range this precautionary estimate by Gaston and Jones has been given as the maximum foraging range for Razorbill, as set out in Table D1. This value has been used for the draft OWE Plan HRA.

D3. Migration Behaviour and Flyways

The UK lies on some of the major migratory flyways of the east Atlantic, with large numbers of waterbirds attracted each year by the relatively mild winter climate and extensive estuarine and wetland habitats. Every year, large numbers of birds traverse the North Sea and Irish Sea during the spring and autumn migrations on their way between breeding and wintering grounds. There appear to be no fixed corridors preferred by migratory birds and instead migration usually takes the form of broad-front. There can be high intensity migration ( i.e. a few days with extremely high numbers) and flight heights can vary depending on the species and weather conditions ( DECC, 2009). Heights can range from just above the water surface to several thousand metres and as migration is costly in terms of energy expenditure, birds will generally try and fly at altitudes where effort is least (Köller et al. 2006).

The issue of potential impacts to migratory birds is key one for this Draft OWE Plan HRA and it is understood that there is a limited amount of robust data on this aspect. This is recognised within the SEA for the Draft OWE Plan (Marine Scotland, 2010) which records that there is a lack of accurate data showing migratory routes and this has also been confirmed via correspondence with the RSPB and SNH as part of consultations with HRA Project Steering Group ( PSG). It is noted however, that the Wildfowl and Wetlands Trust ( WWT) are researching migration routes of several bird species in relation to proposed UK wind farm sites. The WWT work included mapping routes of Greenland Barnacle Geese, Greenland White-fronted Geese and Whooper Swans (Griffin et al., 2010) from or along the west coast of Scotland to Iceland and Svalbard Barnacle Geese routes from South-West Scotland to Norway and Svalbard ( WWT, 2010). Geese and swans were the focus for this research as they tend to fly at less than 100m above sea level and could be at risk of collision with wind turbines. This study was commissioned by COWRIE and involved a tracking study of Whooper Swans to analyse flight heights and migration routes between their breeding grounds in Iceland and the UK in relation to offshore wind farms. The project entailed fitting satellite transmitters to forty known Whooper Swans in winter 2008/2009 at various wintering locations in mainland Britain. These included WWT sites at Caerlaverock ( SW Scotland), Welney ( SE England) Martin Mere ( NW England). Of the 40 individuals tagged, 35 were tracked to Iceland during spring migration 2009. These included 5 birds from Caerlaverock, 13 from Welney and 17 from Martin Mere. In addition 10 transmitters were fitted in August 2009 in Iceland to provide information during autumn migration of the swan's southbound tracks.

As part of this summary review, key scientific literature relating to migratory pathways has been further reviewed to provide additional information on the routes that are taken. In particular, the above study by Griffin et al. (2010) into migration routes and flight heights of Whooper Swans has been reviewed here. In addition the review by Cramp (2000) and the literature that was been compiled as part of this review was summarised to identify the locations of migrant, resident and winter distributions for a range of bird qualifying features. This review is presented in tabular for at the end of this appendix and includes maps of bird distributions that are provided within the Cramp (2000) review.

D3.1 Flight Heights

Griffin et al. (2010) concluded that on average, the flight heights for swans were lower for birds migrating over water along the British coast (9m) compared to when crossing from Britain to Iceland (32m), thus flights occurred below or within the rotor swept area and so potentially at risk of collision. Two records however may provide evidence of avoidance of offshore windfarms. At 8.9km north of Barrow (operational) and 3.8km north of Robin Rigg 23 (near operational) swans were recorded flying at altitudes of 172 metres and 160 metres respectively, where one hour previously their flight heights had been recorded at approximately 50 metres above land (Griffin et al., 2010).

D3.2 Migration Routes

Griffin et al. (2010) found that swans migrating from southeast England (Welney) generally migrated north along the east coast of Britain whereas those from northwest England and southwest Scotland (Martin Mere and Caerlaverock) followed the western coastline (see Image D2).

Image D2 Migration routes of 35 Whooper Swans tracked from the UK to Iceland from WWT Wetland Centres at Welney (red lines), Martin Mere (blue lines) and Caerlaverock (green lines)

Image D2 Migration routes of 35 Whooper Swans tracked from the UK to Iceland from WWT Wetland Centres at Welney (red lines), Martin Mere (blue lines) and Caerlaverock (green lines)

(Griffin et al., 2010)

The swans' satellite tracks were inspected in relation to the distribution of the potential and actual footprint areas of individual windfarms in six key overlapping areas: the East Irish Sea, the Solway Firth, the North Channel/Inner Hebrides, the Greater Wash/North Sea, the Firth of Forth and the Moray Firth. A total of 48 Round 1 (R1), Round 2 (R2), Round 3 (R3) and Scottish Territorial Water ( STW) offshore sites were considered in the analysis.

Of the 19 Whooper Swans tagged at Martin Mere seven flight lines (37%) across the East Irish Sea passed across or immediately adjacent to existing or proposed R1 and R2 windfarm sites with an additional eight tracks (42%) passing within 5km of these sites. Whilst up to ten flight lines (50%) crossing the Solway Firth passed across or immediately adjacent to the existing or proposed R1 or STW windfarm sites with another two (10%) passing within 5 km of these sites. Of these birds crossing the North Channel/Inner Hebrides area no birds were likely to have flown across or adjacent to (within 5km) of STW sites. Of the 15 swans tagged at Welney only one bird stopped and flew across a proposed STW site (Neart na Gaoithe) and one bird flew within 4km of the site proposed at Westermost Rough (R2).

Of the eight birds producing reasonably detailed tracks during the return autumn migration from Iceland, five birds passed across or immediately adjacent to planned offshore windfarm sites with six birds passing within 10km of the planned sites.

Griffin et al. (2010) concluded that swans migrating along the east coast of Britain tended not to pass within or near the footprints of existing or proposed offshore windfarms, preferring to stick close to the coast or overland. However, swans migrating along the west coast more frequently flew into or close to the footprints of several offshore windfarms, preferring to fly over coastal waters. Although this tracking study is not representative of the migration pathways taken by Whooper Swans every year, it is a useful study to add to understanding and risk evaluation to birds arising from windfarms.

Information and knowledge on specific migration routes is also expanding rapidly with recent technological advances and through the application of useful tools ( e.g. Burger & Shaffer, 2008). However it is recognised that identifying distinct flyway routes is difficult both because of the nature and limitations of available information on this subject and because these movements are likely to occur across broad fronts rather than along clearly definable routes. Although little information is known about actual routes taken between breeding and non-breeding areas, a relatively large amount of information is known about the origins and destinations for many bird species, through data from the UK ringing scheme (Langston, 2010 - Wernham et al., 2002, BTO Migration Mapping Tool The destinations outside of the UK where tagged birds migrate to and from Scotland has been reproduced in Table D2. This table is derived from information within the BTO Migration Atlas Project report (Wernham et al., 2002) and is presented within the SEA Environmental Report (Marine Scotland, 2010). As recognised within the SEA document, this information does not specifically describe the migration routes but presents a useful collection of ringing recovery information 'for birds that fly to and from Scotland (not necessarily from other parts of the UK)'.

Further details and maps describing the origins and destinations for many bird species are also presented in Table D3 which provides general information on migrant, resident and winter distributions around the UK and the rest of Europe for a number of bird species (Cramp et al., 2000). The birds listed in this table have been included as they have been identified as qualifying features within SPA designated sites within 100km of the proposed OWE sites.

Table D2. Principal recovery locations for likely focal bird species


Principal Recovery Locations of Ringed Birds Outside of Mainland UK

Arctic Skua

Concentrated around Orkney and Shetland Isles

Arctic Tern

Concentrated around Orkney and Shetland Isles, Scandinavia, W Africa

Barnacle Goose (Nearctic)

Iceland, Greenland, Svalbard

Black-legged Kittiwake

USA, Greenland, Faroes, Continental Europe

Brent Goose (light bellied, E. Canada)


Common Tern

Continental Europe , Ireland, W Africa

Common Guillemot

Continental Europe, Scandinavia, Ireland, Orkney and Shetland Isles, Iceland


Unrecorded in Bird Atlas

European Storm Petrel

Ireland, Iceland, Faroe Islands, Scandinavia, Portugal, S Africa

European Shag

Ireland, Faroe Islands, Continental Europe, Scandinavia

Great Northern Diver

Unrecorded in Bird Atlas

Greenland White fronted Goose

Iceland, Greenland, Orkney

Herring Gull

Ireland, Orkney, Shetland Isles

Manx Shearwater

Ireland, Continental Europe

Migrating waterbirds

Various destinations

Northern Gannet

Ireland, Iceland, Continental Europe, Orkney, Shetland Isles,
northern Scandinavia, NW Africa

Pink-footed Goose

Iceland, Greenland


Continental Europe, Scandinavia, Ireland, Orkney and Shetland Isles

Whooper Swan

Ireland, Western Isles, Orkney

(Marine Scotland, 2010)

Table D3. Migrant, resident and winter distributions, as well as general flight heights, for a number of bird species (Cramp et al., 2000 and references therein)


Summary Information


Map Legend

Common Redshank

Migrate between Iceland and Britain (Orkney to Hampshire) (Ogilvie 1963; Hale 1973; Folkstad 1975; Minton 1975; Boere 1976; Holden & Cleeves, 2002).

Some birds from Scotland and northern England winter in Ireland, but southward movement within Britain more usual, and others continue south to continental coasts (Netherlands to Portugal, especially western France).

Flies freely in lower airspace.


Great Crested Grebe

As few ringed, little known of migration routes, though apparently broad-front overland as well as coastal. Some autumn and winter immigration into British waters from Denmark and Netherlands.

Often active aerially on moonlight nights, visiting neighbouring waters in search of mate or territory. Uses airspace somewhat sparingly, although strong flier once airborne, not often at much height.


Whooper Swan

Migrate between Iceland and Britain (Pennycuick et al., 1996; Holden & Cleeves, 2002).

Once thought to fly at high altitudes between Iceland and the UK; more recent evidence shows that the birds also migrate at just above sea level, and land on the sea in adverse weather or poor visibility (Pennycuick et al., 1996).


Barnacle Goose

East Greenland population migrates via Iceland to winter in west Scotland and Ireland (Salomonsen 1967; Holden & Cleeves, 2002). The Svalbard population moves down the west coast of Norway and across the North Sea, crossing overland in north England and South Scotland to winter in Solway Firth (Holden & Cleeves, 2002).


Greylag Goose

Migrates between Iceland and Scotland and Ireland (Mitchell 1996; Hearn 2000; Swann and Brockway 2002; Swann 2000; Mitchell and Sigfússon 1999; Cranswick et al., 1997; Holden & Cleeves, 2002)


Greenland White-fronted Goose

Geese collared in Scotland, Iceland, and Greenland as part of continuing international marking programme.


Pink-footed Goose

Migrates between Iceland and Britain (Fisher 1951, Thom 1983, Newton et al., 1990, Dix 1991, 1992; Fox et al., 1992; Holden & Cleeves, 2002)


Light-bellied Brent Goose

Migrates between Spitsbergen and Franz Josef Island to Britain and Denmark (Løvenskiold 1964)

Although strong flier, takes wing with some reluctance, and flies no higher than essential.


Bar-tailed Godwit

Winters North Sea and Atlantic coasts of Europe. Major passages in spring and autumn are through Baltic and North Seas and thence along western seaboard.

Exceptional flight capability used at relatively low height except on migration.


Eurasian Wigeon

Migrates between Iceland and Britain

Fenno-Scandia and USSR east populations migrate to winter quarters in west and south-west Europe, especially Britain and Ireland.

Usually fly at no great height.


Northern Pintail

Migrates between Iceland to Britain and Ireland (Bruun 1971; Holden & Cleeves, 2002). Breeding populations of north Russia east to north-west Siberia (Omsk), Fenno-Scandia, and Baltic migrate south-west to winter Netherlands and British Isles.

Use of airspace even freer than for other Anas and often at considerable heights.


Red Knot

Migration occurs from Canada and Greenland to western Europe, including Britain and southern north sea (Andreasson and Råd 1977; Netterstrøm 1970; Holden & Cleeves, 2002)

Winter range of Spitsbergen birds unknown.


Purple Sandpiper

Migrates between Iceland and Norway to Britain (Atkinson et al., 1981; Holden & Cleeves, 2002)

Not known to fly regularly in upper airspace.


Ruddy Turnstone

Migration occurs between Northern Europe, Greenland and Canada to Britain and Ireland (Holden & Cleeves, 2002; Morrison 1975; Clapham 1979; Wilson 1981; Branson et al., 1978)

Also a strong flier, most often within lowest airspace.


Slavonian Grebe

Breeding populations in Iceland, Norway and Scotland winter around Scotland and Atlantic coast of Ireland.

Flies readily, visiting neighbouring waters but observations of high flight lacking


Red-throated Diver

Migration routes not well known. Migration occurs between Spitsbergen, Lapland and USSR to Atlantic and North Sea coasts around Britain and Ireland. 2 chicks from Scotland (Shetland) also found French coast (Finistère, Vendée). Migrants from Europe and Iceland winter around British and Irish coasts (Holden & Cleeves, 2002)

Entirely aquatic and aerial, normally on land only for nesting. Inadequacy of food on small breeding pools requires frequent flighting to better fishing lakes or sea, involving dual aquatic habitat and much use of airspace up to at least 1000 m. Mobility aided by ability to rise readily from small water surfaces, and exceptionally from land.


Common Eider

Partially migratory. Small movement within British and Irish breeders, rarely over 200km (Milne 1965a). Recoveries of Dutch birds in Fife. British and Irish birds do not generally move far from their breeding grounds (Holden & Cleeves, 2002).

Although flying freely, normally keeps to lowest few metres of airspace, mostly over water.


Common Shelduck

Breeders and immatures leave nesting grounds in Britain, Ireland, Belgium, Netherlands, Denmark, Scandinavia, north Germany, north Poland, and Baltic States, for annual moult in German Waddenzee area (Goethe 1961a). Birds from Germany and farther east arrive in Britain in winter (Holden & Cleeves, 2002).

Flies strongly, rising on passage to 1000 m or more above ground.


Great Cormorant

British and Irish populations non-migratory but show extensive dispersal with small proportion crossing English Channel; mainly coastwise, but also inland usually within 60 km of coast (Mills 1965). Recoveries in France and Iberia (mainly Brittany to north Portugal) continuance of southward dispersal in Britain and Ireland, and originate mainly from Irish Sea and Galloway. North Sea effective barrier to eastward movement from Britain, recoveries Norway to north France being quite exceptional.

Circles or soars up to considerable heights and flies overland, often for long distances, occasionally or regularly.



Many Icelandic birds winter Britain and Ireland. Those from north-west Russia, Fenno-Scandia, Baltic states, north Poland, north Germany, and Denmark winter from Denmark to north France and in Britain, with slight onward passage as far as north Spain. Many birds that breed in Iceland and northern Europe spend the winter in Britain and Ireland (Holden & Cleeves, 2002).

Can rise steeply up and away even in awkwardly confined spaces; much given to circling around, usually at heights below c. 500 m.


Greater Scaup

In Iceland, ringing of young showed migration chiefly to Ireland, Britain, and Netherlands (Boyd 1959), with smaller numbers reaching north France, Denmark, and north Germany. Important winter concentrations in Firth of Forth (Scotland).

Take-off somewhat laboured, and use of airspace relatively infrequent.


Long-tailed Duck

No evidence of Icelandic birds reaching continental Europe; yet ones ringed west Greenland moved south-east to Iceland and Denmark, and to Atlantic seaboard of North America, while others wintered in Greenland seas.

Origins of British winterers unknown.

Makes maximum use of airspace, readily flying between coast and inland sites at up to 200-1200 m over land, although usually low over water.


Black (Common) Scoter

Icelandic breeders winter around Ireland, Britain, and Atlantic coasts France, Spain, and Portugal

Movement by small British and Irish population largely unknown, but breeding lakes deserted.

Breeders from Arctic USSR, Sweden and Finland migrate WSW to winter on both sides of North Sea (west coasts of Britain).

Uses airspace often in long formations, and normally at low altitude, but flies fairly high overland; generally flies only when need pressing.


Velet Scoter

Small numbers winter around Britain (mainly east coast)

Has difficulty in becoming airborne and commonly flies low, especially over water.


Common Goldeneye

Breeding populations of Fenno-Scandia, north Germany, Poland, Baltic States and north-west Russia mostly winter Baltic States, Denmark, Netherlands, Britain and Ireland.

Airspace over water and land freely used at wide range of altitudes.


Red-breasted Merganser

Breeding population of Iceland partially migratory; some resident, others migrate to Britain and Ireland. Movements of British breeders not fully known, but at least disperse from inland breeding waters.

Migrants from Finland, Poland and north-west USSR winter in Britain.

Spends much time in aerial excursions, usually at fairly low altitude.


Eurasian Curlew

Large resident population in Ireland, with local movements to coast, though many also winter inland; movements unconfirmed in absence of ringing. Some British birds winter near breeding site, though most move south-west. Thus birds from Scotland and northern England move to British west coast and Ireland; those from southern England to south-west England, some to France and Iberia (Bainbridge and Minton 1978). Scandinavian population moves south-west: Norwegian birds to northern Britain, Ireland, and western France; main wintering area for Swedish birds is Britain and Ireland, though also some on Continental coasts from Denmark to western France (Nørrevang 1959). Some USSR, German and Dutch populations also reach Britain and Ireland (Holden & Cleeves, 2002).

Except on migration flies mainly in lower airspace.


Eurasian Oystercatcher

Birds reared Iceland, Faeroes, and northern Britain moult and winter mainly around Irish Sea and on other western coasts of Britain and Ireland; few reach North Sea coast (Dare 1970; Dare and Mercer 1974b; Anderson and Minton 1978). Some British birds, especially in southern England, remain near breeding areas, but the general trend for these to move south to moult and winter takes some to France and Iberia and exceptionally to Morocco (Buxton 1957; Andrew 1959; Dare 1970; Pienkowski 1972).

Migration also noted frequently across southern Scotland, between Firth of Forth and Solway Firth ( e.g. Andrew 1959), and west of south from north-east England (Evans 1966); by no means certain, however, that Continental immigrants predominate in such movements.

3 recoveries of birds moving between eastern England (all autumn dates) and USSR (Murmansk, Arkhangel'sk), but clearly these atypical.

Considerable movement may occur within a linked estuarine complex, such as Wash-Humber system (England), though apparently little movement between sites within Firth of Forth (Scotland) ( e.g. Minton 1975; M W Pienkowski).

Although a strong flier, shows marked reluctance to venture out of sight of land, and usually travels within lower airspace.


Ringed Plover

Largely migratory but some British birds resident.

North-western populations of Canada and Greenland, majority pass through Britain and Ireland

European populations - Birds from coasts of Scandinavia and Baltic and from East and West Germany south-westwards move widely to wintering areas extending from Britain and Ireland to West Africa.


European Golden Plover

Partially migratory in Britain and Ireland; wholly migratory elsewhere. 23 recoveries of birds ringed Britain as chicks, 21 recovered within Britain, so only minority emigrate. British internal recoveries showed mean movement of 115 km (0-500).

Icelandic population (115 ringing recoveries) wholly migratory, with western route to and through Ireland, western Britain, western France, and Iberia.

Norway to Western Siberian birds, many found in Britain between November to April

Use of airspace (especially above the lowest) normally confined to migration, advertising flights over territory, etc. Wading also infrequent.


Grey Plover

Those occurring in west Palearctic come from breeding population of northern USSR. In Britain, arrives July onward through autumn and winter (Mason 1969, Mason 1972; Branson and Minton 1976).

Wariness leads to frequent use of outstanding powers of flight, mostly in low airspace but migrating flocks fly high in massed formations (Bent 1929).


Northern Lapwing

Britain and Ireland constitute northernmost regular wintering areas. In contrast to continental birds, British breeders mainly make short summer dispersals (within 100 km), though some indication of adult movement west to south-west into Ireland.

Birds from Hungary, Czechoslovakia, Switzerland, and southern West Germany move to Britain.

British Isles especially important as winter quarters for Scandinavian birds; south-westerly movements by those from south and east Baltic countries largely bypass Britain.

In flight, lower airspace usually preferred except on movements, when altitudes of 250-400 m are common and up to 2000 m or more recorded (Meinertzhagen 1920).



Holarctic breeding distribution, wintering on most ice-free coasts of northern hemisphere

Iceland to Britain and western France (Rosenberg et al., 1970; Meltofte 1975; Pienkowski and Dick 1975; Green 1978; Hardy and Minton 1980).

Baltic region to Britain (Minton 1966, Minton 1975; Pienkowski and Dick 1975).

Flies much in lowest airspace, infrequently higher.


Sandwich Tern

Some birds from Britain and Ireland disperse to Netherlands, and vice versa (Møller 1981a). Recoveries of British and Irish birds extend from France to Angola, with 30% of recoveries in Sénégal (Langham 1971; A P Møller).

In some circumstances, as in display, rises into upper airspace, and normally flies somewhat higher over water than most seabirds.



With Holarctic breeding range, winter distribution very large: both sides of Americas and Africa, western and southern Europe, and across southern Asia to Micronesia and Australia (rare in New Zealand).

Although readily taking wing, tends to stay in lowest airspace and not to indulge much in unnecessary flights.


Black-tailed Godwit

Icelandic population winter in large numbers in Ireland and Britain and in western France (Williamson and Ruttledge 1957; Vernon 1963; Fournier and D'Elbée 1974; Prater 1975a).

Although primarily a ground and wading species (up to belly-depth), flies readily at all seasons, rising freely above lower airspace.



Migratory and partially migratory. No evidence yet that any Icelandic breeders emigrate. Similarly, British breeders almost entirely resident, moving short distances (mainly within 150 km) from breeding waters to lakes and sheltered estuaries


Eurasian Teal

All but a few Icelandic breeders migrate to Britain (chiefly Scotland) and Ireland. Most or all breeders from north Russia, Baltic states, Fenno-Scandia, north Poland, north Germany, and Denmark fly south-west in autumn to North Sea wintering grounds, chiefly Netherlands and Britain. Winter distribution between Netherlands, England, Wales, and Ireland greatly dependent on weather.

Breeders of Britain largely resident, moving only in severe weather.

Makes full use of flight, mainly at medium and low heights, for reconnoitring secure places and for daily movements between feeding and resting areas.



Icelandic breeders winter Ireland and Britain. Breeders from Scotland move to Ireland (chiefly) and England.

Those breeding north Germany, Poland, south Sweden, and west-central Russia winter North Sea, chiefly Netherlands and Britain, with some as far as Mediterranean.

Mobile on ground as well as swimming and flying. Takes off less often in steep ascent from confined spaces than A. platyrhynchos or Teal A. crecca, but equally prone to make circling reconnaissance flights at low or medium heights, and frequent local movements between resting, foraging, and breeding haunts.


Common Greenshank

Scottish population - passage occurs through Britain and Ireland

Those to and from Fenno-Scandia and Denmark show movement through Poland, West Germany, eastern Britain, Low Countries, France, Italy, Iberia, and Morocco.

Flight normally in lower airspace except during display and migration when upper airspace up to some hundreds of metres used.


Black-headed Gull

European winter range extends from southern Iceland, Faeroes, southern Norway, western Baltic, Balkans, and southern Russia southwards; common winter visitor in Iberia and around Mediterranean.

Icelandic population recovered in Scotland and Ireland

Fenno-Scandian and Baltic Populations - many migrate to western seaboard countries (North Sea and British Isles to north-west Africa)

Norwegian birds winter mainly around North Sea, with those from western Norway especially in Britain.


Common Tern

Migratory Behaviour - Radar-tracked terns (both Arctic and Common) crossing south Sweden in late July took off in small flocks during evening, ascended at rates of c. 1.2 m/s to heights of 1000-3000 m flying 12-15 m/s (40-55 km/h) in level flight, suggesting that terns start migratory flights in evening and fly at high altitudes at night (Alerstam 1985).

In north Germany, >50% of visible terns migrate <20m or >80% <100 m, and only c. 10% higher than 250 m, single birds >500m (3985 migrating terns observed).

North and east European populations migrate westwards to Great Britain (Norman 2002).

Main wintering areas of British and Irish birds are Ghana and Senegal.


Common Gull (Mew)

Many of the Common Gulls that winter in Britain are birds that nested in Scandinavia (Holden & Cleeves, 2002).


Northern Shoveler

Mostly migratory. Breeders of Iceland all migrate, probably to Ireland or Britain. Most British breeders move southwards to south France, south Spain, north and central Italy, a few to north Africa. Breeders from south Fenno-Scandia and USSR east migrate west and south-west to western seaboard, chiefly Netherlands, Britain, and Ireland.

Circles like other Anas and usually flies below 100 m; shares generic capacity for quick and ready movement between sites.


Bewick's (Tundra) Swan

Wintering sites in Denmark, northwest Germany (few), Netherlands, Britain, and Ireland

Bewick's swan leave Siberia and migrate to Britain, the Netherlands or Germany (Holden & Cleeves, 2002).


Common Pochard

Mainly migratory, but some resident or partially migratory.

Many of the birds that winter in Britain migrate here from northern and eastern Europe and central Russia (Holden & Cleeves, 2002).

Freely uses excellent powers of flight, and will rise on occasion to considerable altitudes.


Tufted Duck

Predominantly migratory though largely resident in a few areas. Some Icelandic breeders winter on coast and other ice-free waters there, but most move to Ireland (chiefly) and Britain. Breeders of northern Britain mainly move south-west to Ireland, though Scottish juveniles recovered exceptionally north to Norway and south to Portugal; those of south Britain believed largely resident.

Vigorous flier making full use of surrounding airspace over fairly wide radius and to considerable heights.


Lesser Black-back Gull

Total winter range now extends from Britain, Mediterranean, Black and Caspian Seas (uncommon), Turkmeniya, and Persian Gulf to Arabian Sea and West and East Africa (sparingly further south).

Main wintering region for British birds comprises Portugal, south-west Spain, and north-west Africa.

Flies readily and strongly, at low and medium altitudes, and less frequently in upper airspace.


Taiga Bean Goose

In west Europe, winters in Britain (few), Denmark, south Sweden, East and West Germany, Netherlands, Belgium, France and Spain.

Birds from Scandinavia migrate to Britain (Holden & Cleeves, 2002).

As forest breeder, can rise steeply from confined spaces, but frequency and patterns of aerial activity otherwise resemble other geese.


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