VULNERABILITY OF SCOTTISH SEABIRDS TO OFFSHORE WIND

The project considers the vulnerability of seabird species to interactions (collision and displacement) with offshore wind farms.


2.3 Adult survival rate

Published data on adult survival rate were used as a measure of the position of each species on the'r-K continuum' which reflects the vulnerability of species to any increase in mortality above natural mortality (species with low adult survival rates tending to have early age of first breeding and high reproductive output and so be less vulnerable to additional mortality than the extreme 'k-selected' species). Data were taken from Garthe and H◘ppop (2004) for the species listed in that paper. Where species were not listed in Garthe and H◘ppop (2004), data were taken from Saether (1989), from del Hoyo et al. (1992, 1996), from Glutz von Blotzheim and Bauer (1982), from individual species studies, or estimated from data for closely related species ( Table 1). Where several estimates were available, preference was given to more recent studies, and studies in the UK rather than from other parts of the world, since survival rates in populations of the same species may sometimes differ between geographical regions, as is particularly evident for example for black-legged kittiwakes in the Pacific and Atlantic (Hatch et al. 1993). For example, the estimated adult survival rate of common eiders in Denmark was 0.8 (Paludan 1962, cited in Cramp and Simmons 1977) but there is a high hunting mortality in that country. In contrast, the common eider is protected in the UK and the survival estimate of Krementz et al. 1997 of 0.895 seems more appropriate ( Table 1).

Adult survival rates were classified on a 1 to 5 scale following the banding used by Garthe and H◘ppop (2004): 1 (adult survival less than 0.749), 2 (adult survival 0.75-0.799), 3 (0.80-0.849), 4 (0.85-0.899), 5 (adult survival above 0.90).

Table 1. Estimates of breeding and winter (or passage) population sizes in Scotland (add data from Forrester et al. 2007), and adult survival rates of seabirds from the literature, or estimated from related species where not directly available.

Species [1] Numbers of breeding pairs in Scotland [2] Numbers in Scotland in winter or passage (p) Percent of population in Scotland Adult survival rate Reference for adult survival rate
Greater scaup n/a 6,000 3 0.5 Cramp & Simmons 1977
Common eider 20,000 64,500 4 0.895 Krementz et al. 1997
Long-tailed duck n/a 15,000 1 0.72 Boyd 1962
Common scoter n/a 27,500 3 0.773 Krementz et al. 1997
Velvet scoter n/a 3,000 1 0.77 From related species
Common goldeneye n/a 11,000 3 0.8 Saether 1989
Red-throated diver 1,200 3,000 10 0.84 Hemmingsson & Eriksson 2002
Black-throated diver n/a 750 5 0.85 Nilsson 1977
Great northern diver n/a 2,000 20 0.86 From related species
Great-crested grebe n/a 1,200 1 0.7 Fuchs 1982
Slavonian grebe n/a 400 5 0.65 From related species
Northern fulmar 486,000 1,000,000 15 0.986 Del Hoyo et al. 1992
Sooty shearwater n/a 7,500 (p) <1 0.9 From related species
Manx shearwater 126,545 200,000 (p) 34 0.9 Perrins et al. 1973
European storm-petrel 32,000 100,000 (p) 8 0.9 Scott 1970
Leach's storm-petrel 48,047 100,000 (p) 1 0.9 From related species
Northern gannet 182,511 5,000 43 0.92 Wanless et al. 2006
Great cormorant 3,600 10,000 8 0.84 Krementz et al. 1989
Shag 26,000 70,000 30 0.83 Potts et al. 1980
White-tailed eagle 32 250 <1 0.7 Cramp et al. 1980
Arctic skua 2,100 5,000 (p) 8 0.84 Del Hoyo et al. 1996
Great skua 9,650 5,000 (p) 61 0.89 Ratcliffe et al. 2002
Black-headed gull 43,200 155,500 3 0.825 Glutz von Blotzheim & Bauer 1982
Common gull 48,100 79,700 7 0.80 Glutz von Blotzheim & Bauer 1982
Lesser black-backed gull 25,000 400 12 0.93 Wanless et al. 1996
Herring gull 72,100 100,000 8 0.93 Glutz von Blotzheim & Bauer 1982
Great black-backed gull 14,800 9,000 15 0.93 Glutz von Blotzheim & Bauer 1982
Black-legged kittiwake 282,200 10,000 10 0.81 Del Hoyo et al. 1996
Little tern 331 900 (p) 3 0.75 From related species
Sandwich tern 1,100 2000 (p) 3 0.87-0.94 Robinson 2010
Common tern 4,800 10,000 (p) 4 0.88 Del Hoyo et al. 1996
Roseate tern 4 10 (p) <1 0.87 From related species
Arctic tern 47,300 100,000 (p) 10 0.875 Del Hoyo et al. 1996
Common guillemot 799,400 760,000 25 0.885 Del Hoyo et al. 1996
Razorbill 93,300 200,000 17 0.905 Del Hoyo et al. 1996
Black guillemot 18,750 50,000 18 0.86 Petersen 1981
Little auk n/a 10,000 <1 0.8 From related species
Atlantic puffin 493,000 20,000 14 0.95 Del Hoyo et al. 1996

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