The effects of released pheasants on invertebrate populations in and around woodland release sites

Abstract

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Large‐scale correlations between gamebird release and management and animal biodiversity metrics in lowland Great Britain

“…Previous work has suggested that particular taxa may be especially sensitive to these activities, but the direction and magnitude of the effects is contentious, with empirical studies and hypothesized mechanisms supporting both increases and decreases (reviewed by Madden & Sage, 2020 ; Mason et al, 2020 ; Sage et al, 2020 ). Some specific examples include: avian predators Pringle et al, 2019 ; invertebrates Hall et al, 2021 ; Woodland birds Draycott et al, 2008 ; vegetation Sage et al, 2009 ).…”

“…Invertebrate populations, predominantly insects, have been proposed to increase due to habitat creation and management or nutrient enrichment (e.g. Hall et al, 2021 ; Robertson et al, 1988 ). Conversely, populations at release sites may decline or change in composition due to direct predation if eaten by omnivorous gamebirds or because of habitat damage (e.g., Hall et al, 2021 ; Neumann et al, 2015 ; Pressland, 2009 ).…”

“…Hall et al, 2021 ; Robertson et al, 1988 ). Conversely, populations at release sites may decline or change in composition due to direct predation if eaten by omnivorous gamebirds or because of habitat damage (e.g., Hall et al, 2021 ; Neumann et al, 2015 ; Pressland, 2009 ). Finally, populations of non‐game farmland and/or woodland birds may increase due to supplementary feeding, the provision or management of improved habitats, or reduced disturbance (e.g., Davey, 2008 ; Hoodless et al, 2006 ; Robertson et al, 1988 ; Sage et al, 2005 , 2009 ).…”

“…This ambiguity in effects of gamebird release and management may arise because our current understanding may be based on studies conducted at just one or a few sites (because of the logistical costs of ecological sampling; but see examples with >10 sites e.g. Davey, 2008 ; Draycott et al, 2008 ; Hall et al, 2021 ; Neumann et al, 2015 ; Pressland, 2009 ; Sage et al, 2009 ) or involve the voluntary participation of shoot owners (presenting an opportunity for sampling bias with more environmentally aware shoot owners opting to host research; e.g. Cox et al, 1996 ; Howard & Carroll, 2001 ; Saad et al, 2021 ; Sanchez‐Garcia et al, 2015 ).…”

“…Effects may vary spatially and/or temporarily, which is problematic if the study focus is on a restricted region or lasts only one or a few seasons (e.g. Hall et al, 2021 ; Heydon et al, 2000 ; Neumann et al, 2015 ; Woodburn & Sage, 2005 ). An alternative approach has been to conduct a correlative study between nationwide records collected within grid squares.…”