Massey K.,Alba Ecology Ltd |
Cosgrove P.,Alba Ecology Ltd |
Massey F.,Alba Ecology Ltd |
Jackson D.,Natural Research Projects Ltd. |
Chapman M.,Natural Research Projects Ltd.
Bird Study | Year: 2016
Capsule: Habitats used by Whimbrel Numenius phaeopus chicks for feeding are significantly different to those used by adults for feeding and nesting. Aim: To identify habitats used by breeding Whimbrel on Mainland Shetland. Methods: Fourteen study sites were used to identify three main components of Whimbrel breeding habitats: (i) adult territorial and foraging habitats; (ii) nest site habitats; (iii) chick feeding habitats. The relationship between these components was investigated using principal components analysis. Results: Habitats used by adults comprised blanket bog dominated by ling heather, cross-leaved heath, common cottongrass, hare’s-tail cottongrass, deergrass and purple moor-grass. There was a thick layer of bryophytes but few forbs. Habitat used for nesting was similar to the general habitat used by adults. The habitats in which Whimbrel chicks foraged were significantly different in structure from the habitats used by adults. The chick feeding areas were characterized by small, wet and often linear features. Conclusion: Habitat requirements by Whimbrel chicks for foraging differed from those of adult Whimbrel for nesting. Habitat structure is important for chicks and the presence of small, wet linear features may be a limiting component on otherwise apparently suitable adult Whimbrel habitats. © 2016 British Trust for Ornithology
Cosgrove P.,Alba Ecology Ltd |
Watt J.,Waterside Ecology |
Hastie L.,University of Aberdeen |
Sime I.,Scottish Natural Heritage |
And 5 more authors.
Biodiversity and Conservation | Year: 2016
All known rivers in Scotland with recent records of freshwater pearl mussels Margaritifera margaritifera were surveyed in 2013–2015 using a standard methodology. Freshwater pearl mussel populations were classed as: (i) apparently extinct in 11 rivers, (ii) not successfully recruiting in 44 rivers, and (iii) evidence of recent successful recruitment in 71 rivers. On a regional basis, a high proportion of extant populations were located in North and West Scotland. In all regions extant populations were characterised by low pearl mussel densities, with 97 of 115 extant Scottish populations defined as ‘rare’ (0.1–0.9 mussels per 1 m 2) or ‘scarce’ (1.0–9.9 mussels per 1 m 2). Only 18 Scottish rivers now hold pearl mussel populations in densities that are considered to be ‘common’ (10–19.9 mussels per 1 m 2) or ‘abundant’ (>20 mussels per 1 m 2). Based on survey evidence, the number of apparently extinct pearl mussel populations in Scottish rivers is now 73. The decline is particularly pronounced in the West Highlands and Western Isles strongholds. The key threats are: (i) pearl fishing, (ii) low host fish densities, (iii) pollution/water quality, (iv) climate change and habitat loss, (v) hydrological management/river engineering and (vi) ‘other factors’, such as non-native invasive species. Over the last 100 years this endangered species has been lost from much of its former Holarctic range. Scotland’s extant M. margaritifera populations continue to be of international importance, but their continued decline since the first national survey in 1998 is of great concern. © 2016 Springer Science+Business Media Dordrecht
Cosgrove P.J.,Alba Ecology Ltd |
Shields D.M.,Alba Ecology Ltd |
Cosgrove C.F.,Alba Ecology Ltd |
Farquhar J.E.,Alba Ecology Ltd |
And 4 more authors.
Journal of Conchology | Year: 2014
All published studies into Scottish populations of the globally threatened and endangered freshwater pearl mussel Margaritifera margaritifera have taken place on exploited (pearl fished) populations. In 2013, detailed studies took place on a large and unexploited freshwater pearl mussel population present in a small, remote Scottish river. This paper outlines the results of this study and compares the size, structure and distribution of this unexploited population with those from exploited Scottish populations. The unexploited population was estimated to contain approximately 0.6 million freshwater pearl mussels, holding the highest densities of mussels per km of river recorded in Scotland. Assessed against targets for assessing conservation sites, the population would be considered to be in favourable condition, holding high densities of freshwater pearl mussels (up to a mean of 84 mussels per m2 over a 50 m×1 m transect area; highest density of 216 mussels in 1 m2), a high proportion of juvenile mussels (23% of samples measured) and many juvenile mussels below 30 mm in size. Current population estimates for most exploited Scottish freshwater pearl mussel populations are far lower than former unexploited population estimates suggest. This unexploited and undescribed population is considered to be the most important freshwater pearl mussel population in Scotland and the UK. Much conservation action is taking place on this species in the UK and this population is a suitable benchmark and reference site for comparisons on what a restored 'healthy' freshwater pearl mussel site should resemble. The undescribed population is threatened by a range of factors and these are discussed. The River X freshwater pearl mussel population is of global importance.