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 Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F371https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F371Tue, 07 Aug 2012 13:58:46 +0100Collected Evidence: Collected Evidence: Remove problematic vegetation A before-and-after study from Japan found higher numbers of long-billed plovers Charadrius placidus after the removal of invasive black locust Robinia pseudoacacia. A study from Australia found lower mortality of Gould’s petrels Pterodroma leucoptera leucoptera following the removal of most of an island’s (native) bird-lime tree Pisonia umbellifera population, whilst a study from New Zealand found that Chatham Island oystercatchers Haematopus chathamensis could nest in preferable areas following invasive marram grass Ammophila arenaria control. A site comparison from the USA found lower densities of several birds in areas with (native) velvet mesquite Prosopis juliflora control.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F432https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F432Wed, 22 Aug 2012 14:43:46 +0100Collected Evidence: Collected Evidence: Remove or control viperine snakes One before-and-after study in Mallorca found that numbers of Mallorcan midwife toad larvae increased after intensive, but not less intensive, removal of viperine snakes.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F830https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F830Wed, 28 Aug 2013 15:01:43 +0100Collected Evidence: Collected Evidence: Remove or disturb leaf litter to enhance germination One replicated, controlled study in Costa Rica found that leaf litter removal decreased the density of new tree seedlings. One replicated, controlled study in Poland found leaf litter removal increased understory plant species richness but decreased their cover.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1246https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1246Fri, 03 Jun 2016 11:07:50 +0100Collected Evidence: Collected Evidence: Remove residential or commercial development We found no studies that evaluated the effects of removing residential or commercial development on shrublands. 'We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1542https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1542Thu, 19 Oct 2017 16:43:11 +0100Collected Evidence: Collected Evidence: Remove residential or commercial development from peatlands We found no studies that evaluated the effects, on peatland vegetation, of removing residential or commercial development from peatlands. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1719https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1719Mon, 13 Nov 2017 15:15:53 +0000Collected Evidence: Collected Evidence: Remove plant litter to maintain or restore disturbance Two studies evaluated the effects on peatland vegetation of removing plant litter to maintain or restore disturbance. One study was in fen meadow and one was in a fen. Plant community composition (2 studies): Two replicated, controlled studies (one randomized, one paired, before-and-after) in a fen meadow in Germany and a fen in Czech Republic found that removing plant litter did not affect plant community composition. Vegetation cover (1 study): One replicated, paired, controlled, before-and-after study in a fen in the Czech Republic found that removing plant litter did not affect bryophyte or tall moor grass cover. Overall plant richness/diversity (2 studies): One replicated, randomized, controlled study in a fen meadow in Germany reported that removing plant litter increased plant species richness and diversity. However, one replicated, paired, controlled, before-and-after study in a fen in the Czech Republic found that removing litter did not affect vascular plant diversity. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1760https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1760Mon, 27 Nov 2017 21:35:49 +0000Collected Evidence: Collected Evidence: Remove pollutants from waste gases before they enter the environment One study evaluated the effects, on peatland vegetation, of removing pollutants from waste gases before release into the environment. The study was in bogs. Plant richness/diversity (1 study): One before-and-after study in bogs in Estonia reported that following installation of dust filters in industrial plants (along with a general reduction in emissions), the number of Sphagnum moss species increased but the total number of plant species decreased. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1789https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1789Tue, 28 Nov 2017 08:18:07 +0000Collected Evidence: Collected Evidence: Remove pipelines and infrastructure following decommissioning We found no studies that evaluated the effects of removing pipelines and infrastructure in place following decommissioning on subtidal benthic invertebrate populations.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.    Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2060https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2060Mon, 21 Oct 2019 13:42:42 +0100Collected Evidence: Collected Evidence: Remove roadkill regularly to reduce kill rate of predators/scavengers We found no studies that evaluated the effects of removing roadkill regularly to reduce the kill rate of predators/scavengers. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2601https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2601Thu, 11 Jun 2020 15:32:32 +0100Collected Evidence: Collected Evidence: Remove or control predators Ten studies evaluated the effects on non-controlled mammals of removing or controlling predators. Seven studies were in North America, one was in Finland, one in Portugal and one in Mexico. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (10 STUDIES) Abundance (6 studies): Three of six studies (including three controlled, one before-and-after and one replicated, paired sites study), in Finland Portugal, Mexico and the USA, found that removing predators increased abundances of pronghorns, moose and European rabbits and Iberian hares. One of these studies also found that mule deer abundance did not increase. The other three studies found that removing predators did not increase mountain hare, caribou or desert bighorn sheep abundance. Reproductive success (2 studies): Two replicated, before-and-after studies (one also controlled), in the USA, found that predator removal was associated with increased breeding productivity of white-tailed deer and less of a productivity decline in pronghorns. However, one of these studies also found that there was no change in breeding productivity of mule deer. Survival (5 studies): Two of five before-and-after studies (including two controlled studies and one replicated study), in the USA, Canada and the USA and Canada combined, found that controlling predators did not increase survival of caribou calves, or of calf or adult female caribou. Two studies found that moose calf survival and woodland caribou calf survival increased with predator control. The other study found mixed results with increases in white-tailed deer calf survival in some but not all years with predator control. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2613https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2613Thu, 11 Jun 2020 17:19:37 +0100Collected Evidence: Collected Evidence: Remove residential or commercial developmentWe found no studies that evaluated the effects, on vegetation, of removing residential or commercial development to restore/create marshes or swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2946https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2946Mon, 01 Mar 2021 16:14:22 +0000Collected Evidence: Collected Evidence: Remove plant litter: freshwater marshes One study evaluated the effects, on vegetation, of removing plant litter from freshwater marshes. The study was in the USA. VEGETATION COMMUNITY Community composition (1 study): One replicated, paired, controlled study in rewetted marshes in the USA found that plots cleared of plant litter contained a plant community characteristic of wetter conditions than uncleared plots after one growing season – but not after two. Overall richness/diversity (1 study): The same study found that plots cleared of plant litter contained a similar number of wetland plant species to uncleared plots, after 1–2 growing seasons. VEGETATION ABUNDANCE                                                          Overall abundance (1 study): One replicated, paired, controlled study in rewetted marshes in the USA found that plots cleared of plant litter had greater cover of wetland plants than uncleared plots after one growing season – but not after two. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3062https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3062Fri, 02 Apr 2021 12:40:27 +0100Collected Evidence: Collected Evidence: Remove plant litter: brackish/salt marshesWe found no studies that evaluated the effects, on vegetation, of removing plant litter from brackish/salt marshes.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3063https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3063Fri, 02 Apr 2021 13:01:21 +0100Collected Evidence: Collected Evidence: Remove plant litter: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of removing plant litter from freshwater swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3064https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3064Fri, 02 Apr 2021 13:01:38 +0100Collected Evidence: Collected Evidence: Remove plant litter: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of removing plant litter from brackish/saline swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3065https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3065Fri, 02 Apr 2021 13:01:57 +0100Collected Evidence: Collected Evidence: Remove pollutants from waste gases before they enter the environmentWe found no studies that evaluated the effects, on vegetation in marshes or swamps, of removing pollutants from waste gases before releasing them into the environment.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3179https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3179Tue, 06 Apr 2021 16:11:49 +0100Collected Evidence: Collected Evidence: Remove or control predators using lethal controls: Sea turtles Four studies evaluated the effects of removing or controlling predators using lethal controls on sea turtle populations. All four studies were in the USA. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (4 STUDIES) Reproductive success (4 studies): Two before-and-after studies (including one controlled study) in the USA found that on islands where raccoons and feral pigs or only feral pigs were eradicated, fewer loggerhead and loggerhead and green turtle nests were predated than before predator control began. One replicated, randomized, controlled study in the USA found that controlling raccoons on short sections of a beach resulted in similar predation of loggerhead turtle nests compared to in sections of the beach with no control. One before-and-after study in the USA found that disruptions to a programme controlling raccoons and armadillos resulted in more predation of loggerhead, leatherback and green turtle nests. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3671https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3671Fri, 10 Dec 2021 11:54:30 +0000Collected Evidence: Collected Evidence: Remove or control predators using lethal controls: Tortoises, terrapins, side-necked & softshell turtles Seven studies evaluated the effects of removing or controlling predators using lethal controls on tortoise, terrapin, side-necked and softshell turtle populations. Four studies were in the USA and three were in Australia. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (7 STUDIES) Reproductive success (7 studies): Six of seven studies (including four replicated, controlled studies) in Australia and the USA found that in areas with mammal or fire ant control, and in two cases with fencing, fewer tortoise, turtle and terrapin nests were predated compared to areas with no control, or before control began. Two studies also found that predation increased again a year after control or in the second year of control. The other study found that following short-term fox control, a similar number of artificial eastern long-necked turtle nests were predated by foxes compared to before control began. Survival (3 studies): Two of three replicated, controlled studies (including one before-and-after study and one randomized study) in Australia and the USA found that in a fenced area with mammal or fire ant control, more gopher tortoise hatchlings survived for one year or at least 150 days compared to fenced areas with no control. The other study found mixed effects of fox control on survival of Murray short-necked turtles and broad-shelled turtles depending on turtle species, age and sex. BEHAVIOUR (1 STUDY) Behaviour change (1 study): One replicated, controlled, before-and-after study in Australia found that in areas with fox control, freshwater turtles nested further from the water and nests were more spread out compared to areas with no control, or before control began. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3672https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3672Fri, 10 Dec 2021 12:10:34 +0000Collected Evidence: Collected Evidence: Remove or control predators using lethal controls: Snakes & lizards Twelve studies evaluated the effects of removing or controlling predators using lethal controls on snake and lizard populations. Four studies were in New Zealand, two were in each of Australia and the Galápagos, and one was in each of Indonesia, Antigua, Mexico and the Bahamas. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (12 STUDIES) Abundance (8 studies): Four of six before-and-after studies (including one replicated, controlled study) in New Zealand, Antigua, Mexico and the Bahamas found that on islands where both Pacific rats and European rabbits, Pacific rats, black rats and cats were eradicated, the abundance of lizards and Antiguan racer snakes. One study found that on an island where black rats were eradicated the number of San Salvador rock iguanas remained similar compared to before eradication. The other study found that eradicating mice had mixed effects on the abundance of lizards. One study also found that lizard abundance on an island with eradication was initially lower than on a predator free island, but after two years was similar or higher. One controlled, before-and-after study in Australia found that across areas with fox and cat control or only fox control, gecko and skink numbers were similar to an area with no control, but dragon lizard numbers were lower. One replicated, site comparison study in Australia found that in areas with fox control sand goanna abundance was higher and there was mixed effects on small lizard abundance compared to in areas with no control. Reproductive success (1 study): One before-and-after study in the Galápagos found that on an island where cats were eradicated the number of offspring of reintroduced Galápagos land iguanas was higher than before cat control began. Survival: (2 studies): One study in New Zealand found that survival of captive-bred Otago skinks released into an enclosure after mouse eradication was higher compared to when skinks were released in the presence of mice. One study in Indonesia reported no mortality of monitor lizards following use of poison baits to control black rats. Condition (2 studies): One of two studies in Indonesia and the Galápagos found that on an island where black rats were controlled, rodenticide was detected in the livers of lava lizards for up to 850 days after its use began. The other study reported no illness in monitor lizards following use of poison baits to control black rats. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3673https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3673Fri, 10 Dec 2021 12:27:59 +0000Collected Evidence: Collected Evidence: Remove or control predators using lethal controls: Crocodilians We found no studies that evaluated the effects of removing or controlling predators using lethal controls on crocodilian populations. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3674https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3674Fri, 10 Dec 2021 13:42:04 +0000Collected Evidence: Collected Evidence: Remove or control predators using lethal controls: Tuatara One study evaluated the effects of removing or controlling predators using lethal controls on tuatara populations. This study was in New Zealand. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Abundance (1 study): One replicated, controlled, before-and-after study in New Zealand found that after eradicating Pacific rats the abundance of tuatara was higher on islands where rats were eradicated than on islands where some rats remained, and that the percentage of total tuatara that were juveniles increased. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3675https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3675Fri, 10 Dec 2021 13:44:19 +0000Collected Evidence: Collected Evidence: Remove or control predators by relocating them Two studies evaluated the effects on reptile populations of removing or controlling predators by relocating them. Both studies were in the USA. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (2 STUDIES) Abundance (1 study): One before-and-after study in the USA found that after raccoons were live trapped and relocated, the number of freshwater turtle hatchlings increased for 2–3 years, then decreased again after 3–4 years. Reproductive success (2 studies): One of two studies (including one replicated, controlled study) in the USA found that within a fenced area where predators were removed by both relocating and lethal controls, fewer gopher tortoise nests were predated than outside the fenced area where predators were not removed. The other study found that after raccoons were live trapped and relocated, predation of freshwater turtle nests decreased for 2–3 years, then increased again after 3–4 years. Survival (1 study): One replicated, controlled study in the USA found that within a fenced area where predators were removed by both relocating and lethal controls, survival of gopher tortoise hatchlings was higher than outside the fenced area where predators were not removed. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3676https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3676Fri, 10 Dec 2021 13:46:20 +0000Collected Evidence: Collected Evidence: Remove or control predators using fencing and/or aerial nets Ten studies evaluated the effects on reptile populations of removing or controlling predators using fencing and/or aerial nets. Five studies were in Australia, two were in each of the USA and New Zealand and one was in Spain. COMMUNITY RESPONSE (1 STUDY) Richness/diversity (1 study): One controlled study in Australia found mixed effects of fencing in combination with removal of invasive mammals on reptile species richness. POPULATION RESPONSE (10 STUDIES) Abundance (5 studies): Three of four studies (including one paired sites, controlled, before-and-after study) in Australia found mixed effects of fencing or fencing and removal of invasive mammals on the abundance of reptiles. The other study found that small lizards were more abundant inside fenced areas than outside fenced areas. This study also found mixed effects of fencing on the abundance of skinks and geckos. One replicated, controlled, before-and-after study in Australia found that in areas with fencing the abundance of reptiles increased more over time than in areas with no fencing. Reproductive success (2 studies): One of two replicated, controlled studies (including one randomized study) in the USA and Spain found that in areas with fencing in combination with predator removal, gopher tortoise nests were predated less frequently than in areas with no corrals or fencing with predator removal. The other study found mixed effects of fencing on predation of artificial western Hermann’s tortoise nests. Survival (4 studies): Two of three studies (including one replicated, randomized, controlled study) in New Zealand and the USA found that in areas with fencing in combination with predator removal, more gopher tortoise hatchlings survived for a year than in areas with no fencing or predator removal or survival of captive-bred Otago skinks released into an enclosure was higher when mice had been eradicated compared to when skinks were released in the presence of mice. The other study found that use of predator exclosure fences did not result in increased survival of McCann’s skink compared to areas without exclosures. One replicated, randomized, controlled study in the USA found that in enclosures designed to exclude small mammals with additional fencing and overhead netting, a similar number of gopher tortoise hatchlings were predated by vertebrate predators compared to in unmodified enclosures. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3677https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3677Fri, 10 Dec 2021 13:52:47 +0000Collected Evidence: Collected Evidence: Remove or control toxic invasive amphibians (e.g. cane toads, Asian toads) We found no studies that evaluated the effects of removing or controlling toxic invasive amphibians on reptile populations. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3699https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3699Fri, 10 Dec 2021 18:52:55 +0000
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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