Collected Evidence: Collected Evidence: 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.  Collected, 07 Aug 2012 13:58:46 +0100Collected Evidence: Collected Evidence: Control avian predators on islands Out of 10 studies, six before-and-after studies from North America, Australia and Europe found that controlling avian predators led to increased population sizes, reduced mortality or increased reproductive success in seabirds on islands. The North American studies had several interventions, so increases could not be linked directly to predator control, and one found that increases were only at one of two sites studied. Two controlled studies in Europe found little evidence that crow control led to increased reproductive success in gamebirds or raptors on islands. A North American study found that, despite higher reproductive success, very few birds returned to the study site after predator removal. A study from North America found that an Atlantic puffin Fratercula arctica translocation programme, combined with the culling of predatory gulls, appeared to be successful. A study from the UK found that the number of common terns Sterna hirundo and black-headed gulls Larus ridibundus declined on gravel islands despite the attempted control of large gulls.  Collected, 07 Aug 2012 14:43:03 +0100Collected Evidence: Collected Evidence: Control mammalian predators on islandsThe assessment of the effectiveness of this intervention was based on a total of 33 studies across all species groups. See Background section below for links to the evidence for the control of mammalian predators on islands on specific species groups. A paired sites study from Finland and a literature review from the UK found increased bird species richness and abundance or population recoveries and recolonisations, following the control or eradication of mammalian predators. Predators removed included American mink Mustela vison, rats Rattus spp. pigs Sus scrofa, cats Felis catus, dogs Canis familiaris and grey fox Dusicyon griseus.    Collected, 07 Aug 2012 15:31:12 +0100Collected Evidence: Collected Evidence: Control mammalian predators on islands for wildfowlA before-and-after study from Alaska found that cackling geese Branta hutchinsii returned to a total of eight nesting islands between the 1970s and 1991, following the removal of Arctic foxes Alopex lugopus from the islands.Collected, 07 Aug 2012 15:47:51 +0100Collected Evidence: Collected Evidence: Control mammalian predators on islands for seabirds We found 16 before-and-after studies, one paired sites study and one literature review from around the world, all describing positive seabird responses to the removal or control of mammalian predators (mainly rats Rattus spp. and feral cats Felis catus) from islands. Of these 18 studies, seven found either large population increases or recolonisations following predator eradication or control. Two of these found only partial population increases or recolonisations: a study from Alaska. Twelve studies found increases in reproductive success and survival or decreases in predation and mortality following predator control. In one case there was also a small population increase. Rats and mice Mus musculus were controlled in twelve studies, mostly examining burrow-nesting seabirds; cats in eight, mostly on ground or cliff-nesting seabirds; and other species in two.  Collected, 07 Aug 2012 15:57:05 +0100Collected Evidence: Collected Evidence: Control mammalian predators on islands for gamebirdsA single replicated and controlled study on two Swedish islands found that four species of gamebirds had larger broods, and more females had chicks, when predators were controlled. Two of the species also showed population-level responses.  Collected, 07 Aug 2012 18:51:53 +0100Collected Evidence: Collected Evidence: Control mammalian predators on islands for railsTwo before-and-after studies from Australia and the Galapagos Islands found increases in survival or population density of rails on islands following the removal of feral pigs Sus scrofa.  Collected, 08 Aug 2012 13:42:59 +0100Collected Evidence: Collected Evidence: Control mammalian predators on islands for waders A controlled before-and-after study in New Zealand found that the Chatham Island oystercatcher Haematopus chathamensis population increased following the removal of feral cats Felis catus and other species. A second controlled before-and-after study in Alaska, USA, found small increases in black oystercatcher Haematopus bachmani breeding populations on two islands, but the overall population only increased on one, declining on the other.  Collected, 08 Aug 2012 13:46:45 +0100Collected Evidence: Collected Evidence: Control mammalian predators on islands for raptorsA study in Mauritius found that numbers of Mauritius kestrel Falco punctatus may have increased following the trapping of predators near nests. However, the authors do not provide any data to support this observation.  Collected, 08 Aug 2012 14:14:47 +0100Collected Evidence: Collected Evidence: Control mammalian predators on islands for pigeonsTwo before-and-after trials on Mauritius found that fewer pink pigeon Columba mayeri nests were predated and more chicks were fledged following systematic and intensive rat control.  Collected, 08 Aug 2012 14:19:04 +0100Collected Evidence: Collected Evidence: Control mammalian predators on islands for parrotsTwo before-and-after studies in New Zealand found reduced nest predation and successful recolonisation of an island following invasive mammal eradication or control.  Collected, 08 Aug 2012 14:38:19 +0100Collected Evidence: Collected Evidence: Control mammalian predators on islands for songbirds Two before-and-after trials in the Seychelles and Cook Islands describe population increases in magpie robins and monarch flycatchers following cat and rat control. A before-and-after study from New Zealand found that the population of South Island robins Petroica australis australis was almost identical before and after rat control. Two studies found higher reproductive success in monarch flycatchers and shrikes in areas with rodent control, compared to areas without control. However, this was climate dependent in shrikes. A before-and-after study from Hawaii found lower predation on artificial nests after intensive rodent control.  Collected, 08 Aug 2012 14:43:04 +0100Collected Evidence: Collected Evidence: Control invasive ants on islandsA replicated, randomised and controlled, before-and-after paired sites study in the USA found temporarily increased fledging success, but no decrease in injuries inflicted by Solenopsis geminata on wedge-tailed shearwaters Puffinus pacificus following ant control. However, there was no change in fledging success or injury rate on an island dominated by the big-headed ant Pheidole megacephala following its eradication, either on the experimental or control island.  Collected, 08 Aug 2012 15:13:13 +0100Collected Evidence: Collected Evidence: Control predators not on islands for seabirds A before-and-after study from New Zealand found an increase in a tern population following intensive trapping of invasive mammals. A before-and-after study from Canada found increases in tern fledging success following gull control.  Collected, 08 Aug 2012 16:42:50 +0100Collected Evidence: Collected Evidence: Control predators not on islands for wildfowl Six out of seven studies, mostly from North America found higher reproductive success of ducks when mammalian predators were removed. A before-and-after study found higher survival of captive-bred brown teal Anas chlorotis following feral cat Felis catus control. One meta-analysis from the USA and Canada found that ducks on sites with mammalian predator removal did not have higher reproductive success and trends in reproductive success were no more positive than on sites without predator control.  Collected, 08 Aug 2012 16:53:51 +0100Collected Evidence: Collected Evidence: Control predators not on islands for gamebirds Four controlled studies in Europe found increased populations or productivity of grouse and partridges on sites with predator removal. One study tested multiple interventions simultaneously. A fifth replicated UK study found no increase in grouse densities or reproductive success on sites with gamekeepers, compared to those without.  Collected, 08 Aug 2012 17:25:00 +0100Collected Evidence: Collected Evidence: Control predators not on islands for railsA single study from the USA found more California clapper rails Rallus longirostris obsoletus on sites with higher numbers of foxes removed.  Collected, 08 Aug 2012 17:35:18 +0100Collected Evidence: Collected Evidence: Control predators not on islands for cranesA single trial from the USA found that greater sandhill cranes Grus canadensis tabida had higher hatching and fledging success in years with predator control, compared to years without control.  Collected, 08 Aug 2012 17:37:18 +0100Collected Evidence: Collected Evidence: Control predators not on islands for waders Three out of four controlled studies in the UK and the USA found some evidence for higher reproductive success or lower predation rates for waders in areas or years with predator removal, although one UK study found that only three of six species investigated had increased reproductive success in years with predator removal. Predators removed were carrion crows Corvus corone, gulls Larus spp., red foxes Vulpes vulpes and cats Felis catus.  Collected, 08 Aug 2012 17:40:34 +0100Collected Evidence: Collected Evidence: Control predators not on islands for parrotsA replicated, controlled trial in New Zealand found increased kaka Nestor meridionalis nesting success and lower predation at sites with mammal predator removal than at unmanaged sites.  Collected, 09 Aug 2012 13:05:06 +0100Collected Evidence: Collected Evidence: Control predators not on islands for songbirds A before-and-after study from New Zealand found that a reintroduced population of New Zealand robins Petroica australis declined without predator control and increased with rat poisoning. Two UK studies, one non-experimental, found increased populations of some species following control of bird and mammal predators. One replicated, controlled study from New Zealand found lower New Zealand robin survival in areas where rodent bait was broadcast, but no difference with controls when dispensers were used. Six studies from New Zealand, Australia, UK found increased nest success or survival (in one case with artificial nests) following bird and mammal predator control. One randomised, replicated and controlled study from the USA found no difference in nest survival in a site with mammalian predator removal.  Collected, 09 Aug 2012 13:08:55 +0100Collected Evidence: Collected Evidence: Reduce predation by translocating predatorsTwo studies from France and the USA found local population increases or reduced predationfollowing the translocation of predators away from an area.  A study in Saudi Arabia found that predation was no lower when predators were translocated from the bird release site.  Collected, 09 Aug 2012 13:39:34 +0100
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What Works in Conservation

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