title: Can hedgerow management mitigate the impacts of predation on songbird nest survival?
abstract: Nest predators can have significant impacts on songbird reproductive success. These impacts may be amplified by habitat simplification and here we test whether sympathetic management of farmland hedgerows can reduce nest depredation, especially by corvids. We test whether songbirds select nest sites according to structural features of hedgerows (including nest visibility and accessibility), and whether these features influence nest predation risk. Songbirds selected nesting sites affording higher vegetation cover above the nest, increased visibility on the nest-side of the hedgerow and reduced visibility on the far side of the hedge. Nest survival was unrelated to corvid abundance and only weakly related (at the egg stage) to corvid nest proximity. Nest survival at the chick stage was higher where vegetation structure restricted access to corvid-sized predators (averaging 0.78 vs. 0.53), and at nests close to potential vantage points. Overall nest survival was sensitive to hedgerow structure (accessibility) particularly at low exposure to corvid predation, while the overall impact of corvid exposure was dependent on the relationship involving proximity to vantage points. Nest survival over the chick stage was much higher (0.67) in stock-proof, trimmed and mechanically cut hedgerows, (which tended to provide lower side visibility and accessibility) than in recently laid, remnant or leggy hedgerows (0.18). Long-term reductions in the management of British hedgerows may therefore be exposing nesting songbirds to increased predation risk. We recommend regular rotational cutting of hedgerows to maintain a dense woody structure and thereby reduce songbird nest predation.
authors: RSPB Centre for Conservation Science, RSPB, The Lodge, Sandy, Bedfordshire, SG19 2DL, UK. Electronic address: Jenny.C.Dunn@gmail.com.
authors: Jenny C
authors: JC
authors: Dunn
authors: RSPB Centre for Conservation Science, RSPB, The Lodge, Sandy, Bedfordshire, SG19 2DL, UK.
authors: Derek
authors: D
authors: Gruar
authors: Allerton Project, Game and Wildlife Conservancy Trust, Loddington House, Loddington, Leicestershire, LE7 9XE, UK.
authors: Chris
authors: C
authors: Stoate
authors: Allerton Project, Game and Wildlife Conservancy Trust, Loddington House, Loddington, Leicestershire, LE7 9XE, UK.
authors: John
authors: J
authors: Szczur
authors: RSPB Centre for Conservation Science, RSPB, The Lodge, Sandy, Bedfordshire, SG19 2DL, UK.
authors: Will J
authors: WJ
authors: Peach
mesh_terms: D000383:Agriculture / Q000379:methods*; D000818:Animals; D017753:Ecosystem; D004739:England; D009425:Nesting Behavior; D011235:Predatory Behavior; D012098:Reproduction; D020308:Songbirds / Q000502:physiology*
keywords: Corvids; Farmland birds; Farmland conservation; Nest predation; Predator-habitat interactions