Literature review to assess bird species connectivity to Special ...

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2.6.5 Habitat use Likely habitat use Golden eagles are typically found in mountainous, coastal and upland regions (Cramp & Simmons, 1983), with open areas of short or sparse vegetation, especially slopes and plateaus and good visibility for hunting (McGrady et al., 1997). Additionally, particular geographical features, such as south-west facing slopes that provide good uplift in prevailing weather conditions, are important for efficient soaring and hunting. The chosen habitat must provide secure alternative nest sites with easy open access (Cramp & Simmons, 1983). Golden eagles typically nest on cliffs, between 150m and 450m a.s.l. (Watson & Dennis, 1992). 5% of Scottish breeders nest in trees (McGrady et al., 1997). McGrady et al. (1997) recorded habitat preferences. These were (most preferred first): montane; heather; coarse grassland; bracken; smooth grassland with scrub; bog; broadleaved forest; pre-thicket forest/low scrub; post-thicket forest; improved pasture; water; anthropogenic smooth grassland without scrub; salt marsh; wetlands; and cliff. Golden eagles tend to avoid closed canopy forest and inland water (Watson, 1997) although Crane & Nellist (1999) suggest that sea surrounding a headland eyrie can be used for observational and patrol flights. In situations where pairs are breeding on islands with no ground predators, foraging can occur over a wider range of habitat types, including at low elevations (Andrew Stevenson pers. comm.). 2.6.6 Prediction models Current models that predict habitat use by golden eagles are the RIN model of McGrady et al. (1997, 2002), which was refined by McLeod et al. (2003) to form the PAT (Predicting Aquila Territory) model. In areas where there is little or no high-quality observational data on golden home ranges, the use of PAT modelling has proven useful for predicting golden eagle ranging behaviour (Whitfield et al., 2001; McLeod et al., 2003). The ‘PAT’ model brings together the known locations of eagle territory centres, digital elevation and habitat cover data in a GIS environment to predict the ranging of the birds within their core area (within 2-3 km of the nest). Predictions are generated from these data along with the species’ known habitat preferences at better-studied sites. The main applications of the model are in predicting eagle responses to developments and mitigation. Information on habitat management and other mitigation, or the size and location of developments, can usefully predict how ranging behaviour is likely to be influenced. While PAT modelling is less accurate than high quality field observations, it produces more reliable response predictions than those based simply on distance from the nest. 2.6.7 Winter behaviour Winter dispersal Adult golden eagles hold home ranges that encompass both their hunting and nesting territory and are occupied all year round (Hardey et al., 2006). Young golden eagles leave their natal territory between 60 and 80 days after fledging (Watson, 1997). Ring recoveries give some indication of mean dispersal distances (Table 3). 18
Grant & McGrady (1999) followed two juveniles for periods from one month to twenty-one months. One bird moved varying distances over a 15 month period, the greatest being 75km. Another made similar long distance movements over a 10 month period, with 35km being the greatest distance recorded from its natal home range. Details of juvenile ranging behaviour are emerging from a study of a satellite-tracked juvenile by the Highland Foundation for Wildlife in partnership with the Cairngorms National Park Authority, Scottish Natural Heritage and Glenfeshie Estate (Highland Foundation for Wildlife 2008). The juvenile female ranged up to 80km from its birth place by mid-April in its first winter, and was recorded up to 140km away in its first spring (Highland Foundation for Wildlife 2008). A study of juvenile dispersal in south west Spain, using satellite tags on thirteen individuals, recorded mean areas of 371300 ± 258600ha for males and 1065200 ± 745100ha for females (Soutullo et al., 2006). This is equivalent to distances of 34.4km for males and 58.2km for females. Table 3 - Ages and mean dispersal distances of golden eagles in Great Britain from ring recoveries (taken from Grant & McGrady, 1999) Age (calendar years) No of recoveries Mean and range of dispersal distance (km) 1-2 24 67.6 (11-161) 3 4 44.0 (27-77) 4 4 22 (7-47) 7 1 11 19
Page 1 and 2: Scottish Natural Heritage Commissio
Page 3 and 4: COMMISSIONED REPORT Summary Literat
Page 5 and 6: Tables Page Table 1 - Species revie
Page 7 and 8: 1. INTRODUCTION Proposals for opera
Page 9 and 10: 2. SPECIES ACCOUNTS 2.1 Red-throate
Page 11 and 12: 2.2 Black-throated diver 2.2.1 Fora
Page 13 and 14: High flying, up to 1000m, can also
Page 15 and 16: moved in successive years between s
Page 17 and 18: 2.5 Goshawk 2.5.1 Foraging Core for
Page 19 and 20: Nest locations were regularly distr
Page 21 and 22: Ringing recoveries of an adult fema
Page 23: 1986). A pair on a home range in th
Page 27 and 28: 2.7.5 Habitat use Likely habitat us
Page 33 and 34: will subsequently role away, or til
Page 35 and 36: 2.11 Short-eared Owl 2.11.1 Foragin
Page 37 and 38: 2.12 Black grouse 2.12.1 Foraging H
Page 39 and 40: making longer movements (5 to 10km)
Page 41 and 42: Thompson, 1998). Other interactions
Page 43 and 44: 2.14 Greenshank 2.14.1 Foraging Cor
Page 45 and 46: 2.15 Dunlin 2.15.1 Foraging Foragin
Page 47 and 48: 2.16 Curlew 2.16.1 Foraging Core fo
Page 49 and 50: 2.18 Wintering geese 2.18.1 Foragin
Page 51 and 52: to about 7 km from the roost (Malco
Page 53 and 54: 3.2 Foraging ranges during winter s
Page 55 and 56: 4. REFERENCES Arroyo, B.E. Leckie,
Page 57 and 58: Fuller, R.J. & Lloyd, D. (1981). Th
Page 59 and 60: Mearns, R. (1985). The hunting rang
Page 61 and 62: Rebecca, G.W. & Bainbridge, I.P. (1
Page 63 and 64: Whittingham, M.J., Percival, S.M. &

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