Habitat correlates of Eurasian Woodcock Scolopax rusticola abundance in a declining resident population

Woodcock - Graham Giddens

Author(s): Heward, C.J., Hoodless, A.N., Conway, G.J., Fuller, R.J., MacColl, A.D.C. & Aebisher, N.J.

Published: 2 June 2018

Journal: Journal of Ornithology

Digital Identifier No. (DOI): 10.1007/s10336-018-1570-z

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Woodcock, along with many other woodland bird populations, have been in long-term decline. Habitat change has been indicated as a possible cause for some species, but evidence is sparse for others, including Woodcock, due to an incomplete knowledge of their habitat requirements, which we can now examine.

National BTO/GWCT Woodcock surveys undertaken in 2003 and 2013 provided data from 807 and 823 randomly selected 1 km squares, respectively. Woodcock counts were compared with a range of landscape-scale habitat variables as well as local habitat measures recorded by surveyors, using generalised linear mixed models. Habitat variables were measured at a variety of spatial scales using ring buffers, however high correlation between scales limits interpretation. 

The results show that, at large landscape scales, breeding Woodcock abundance was correlated with total woodland area and woodland type. Woodcock were more abundant in woods containing a more heterogeneous mix of woodland habitat types and in woods further from urban areas. On a smaller spatial scale, Woodcock were less likely to be found at sites dominated by Beech and more likely to occur in woods containing Birch. 

The Woodcock’s association with large, heterogeneous woods and the apparent attractiveness of certain woodland types present the most relevant topics for future research into the role of habitat change in long-term declines.

Abstract

In Europe, woodland bird populations have been declining since at least the 1970s, and in Britain, around one third of woodland bird species have undergone declines over this period. Habitat change has been highlighted as a possible cause, but for some species clear evidence of this is lacking owing to an incomplete knowledge of the species’ habitat requirements. Here, we analyse national data to explain the variation in abundance of a declining woodland bird, the Eurasian Woodcock. A nationwide, species-specific survey of breeding Woodcock was conducted in 2003 and 2013 at 807 and 823 randomly selected 1-km squares respectively. The counts were compared with a range of landscape-scale habitat variables as well as local habitat measures recorded by surveyors, using generalised linear mixed models. Habitat variables were measured at a variety of spatial scales using ring buffers, although our analyses show that strong collinearity between scales hinders interpretation. At large landscape scales, breeding Woodcock abundance was correlated with total woodland area and the way this interacted with woodland type. Woodcock were more abundant in woods containing a more heterogeneous mix of woodland habitat types and in woods further from urban areas. On a smaller spatial scale, Woodcock were less likely to be found at sites dominated by beech Fagus spp. and more likely to occur in woods containing birch Betula spp. The Woodcock’s association with large, heterogeneous woods and the apparent attractiveness of certain woodland types present the most relevant topics for future research into the role of habitat change in long-term declines.
Staff Author(s)