Action: Control predators not on islands
A single replicated and randomised, paired sites study from the UK found that plots with predator control had increased density and fledgling success of breeding birds.
When predators are controlled on continental sites, rather than islands, the chances of eradicating predators are far smaller and may not be desirable – many of the studies we have captured describe the control of native predators.
We have classed landmasses above approximately 5,000 km2 as ‘non-islands’ because the largest island where eradication has so far been attempted (as of July 2011) is South Georgia, South Atlantic, at 3,718 km2.
One study discussing the impacts of predator control on bird communities is described below; studies describing the effects on individual taxa are in subsequent sections.
Supporting evidence from individual studies
A replicated, randomised, paired site study from March-July in 2000-2008 in 2 pairs of plots (9.3-14.4 km2) in Northumberland, UK (Fletcher et al. 2010) found that plots where predators were experimentally controlled displayed increased density and fledgling success of breeding birds. Reductions in foxes Vulpes vulpes and carrion crows Corvus corone led to an average threefold increase in the percentage of pairs fledging young of lapwing Vanellus vanellus, golden plover Pluvialis apricaria, curlew Numenius arquata, red grouse Lagopus lagopus scoticus and meadow pipit Anthus pratensis; and subsequently led to increases in breeding numbers (? 14%/year) of lapwing, curlew, golden plover and red grouse, all of which declined in the absence of predator control (? 17%/year). There was no significant effect of predator culling for any wader species. Predator culling reduced the abundance of fox by 43% and crow 78%.