Action: Remove or control predators to enhance bird populations and communities
- A meta-analysis and a systematic review both found that reproductive success increased with predator removal, but their exact findings differed.
- The meta-analysis found that post-breeding population size increased, whilst the systematic review found that this was true on mainlands, but not islands and that breeding populations also increased.
Supporting evidence from individual studies
A meta-analysis of 20 published studies (Côté & Sutherland 1997) showed that predator removal had a large, positive effect on hatching success – with removal areas showing higher hatching success on average than 75% of control areas – and led to a significant increase in post-breeding population size (i.e. autumn density), although no significant impact was detected on breeding population size.
A 2010 systematic review (Smith et al. 2010) found that removing predators tended to lead to increased reproductive success (hatching and fledging success) and breeding populations in birds. On mainlands, but not islands, predator removal also tended to increase post-breeding population size. Whether predators were native or not, the population trend of the bird population and whether the species was migratory or a game species did not affect responses to predator removal.