Correlates of the change in Ring Ouzel Turdus torquatus abundance in Scotland from 1988-91 to 1999

CapsuleThe change was correlated with environmental, habitat and management variables. Aims To identify factors correlated with a population decline and range contraction between 1988-91 and 1999. Methods Regression models are used to describe the variation in Ring Ouzel abundance in 1988-91, and th...

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Bibliographic Details
Published in:Bird study 2003-07, Vol.50 (2), p.97-105
Main Authors: Buchanan, Graeme M., Pearce-Higgins, James W., Wotton, Simon R., Grant, Murray C., Whitfield, D. Phil
Format: Article
Language:English
Subjects:
forestry
Molinia
moorland
Nardus
population change
range contraction
thrush
Turdus
uplands
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Summary:CapsuleThe change was correlated with environmental, habitat and management variables. Aims To identify factors correlated with a population decline and range contraction between 1988-91 and 1999. Methods Regression models are used to describe the variation in Ring Ouzel abundance in 1988-91, and the change in Ring Ouzel abundance between 1988-91 and 1999. Results The abundance of Ring Ouzels in 1988-91 was negatively correlated with improved pasture, but positively with heather/smooth grass mosaic and Nardus/Molinia grassland. There was also a positive quadratic correlation with rock cover. A decline in Ring Ouzels between 1988-91 and 1999 was most likely on tetrads with shallow gradients, and outside of a 350-750 m altitudinal range. The change in ouzel numbers was also negatively correlated with both the initial area of conifer forest and heather/smooth grass mosaic. The rate of loss was greatest in those areas with a low Ring Ouzel abundance in 1988-91, although this effect was non-significant once habitat was accounted for. Conclusions The abundance of Ring Ouzels was linked to heather-grass mosaics, while declines were greater in tetrads lacking topographical features known to be selected by nesting ouzels. The negative relationship between forestry and population change suggests that large-scale afforestation of the uplands is a cause of concern.
ISSN:0006-3657
1944-6705
DOI:10.1080/00063650309461300