Collected Evidence: Collected Evidence: Install overpasses as road/railway crossing structures for bats Four studies evaluated the effects of installing overpasses as road crossing structures for bats. Three studies were in Europe and one in Australia. COMMUNITY RESPONSE (1 STUDY) Richness/diversity (1 study): One site comparison study in Australia found that the same number of bat species were recorded at an overpass and in nearby forest and bushland. POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (3 STUDIES)      Use (3 studies): Two replicated studies (including one site comparison) in Ireland and France found that two or three bat species/species groups used overpasses but up to three-quarters of bats crossed the road below at traffic height or crossed at other nearby locations. One study in the UK found that an overpass with planters was used by two-thirds of crossing bats, and an unvegetated overpass with a paved road over it was not used by crossing bats. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F977https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F977Fri, 20 Dec 2013 14:10:25 +0000Collected Evidence: Collected Evidence: Install hop-overs as road/railway crossing structures for bats We found no studies that evaluated the effects of hop-overs as road/railway crossing structures for bats on bat 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%2F980https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F980Fri, 20 Dec 2013 14:14:29 +0000Collected Evidence: Collected Evidence: Install mechanical barriers to deter primates (e.g. fences, ditches) We found no evidence for the effects of installing mechanical barriers to prevent primates from entering agricultural areas and raiding crops on primate populations. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested 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%2F1436https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1436Tue, 17 Oct 2017 10:22:52 +0100Collected Evidence: Collected Evidence: Install rope or pole (canopy) bridges One study in Brazil found that black lion tamarins and capuchins used a pole bridge to cross a road. One before-and-after study in Belize found that a black howler monkey population increased after the construction of pole bridges over man-made gaps. One before-and-after study in Madagascar found that all six monitored lemur species used bridges to cross roads and pipelines. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1457https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1457Tue, 17 Oct 2017 13:28:40 +0100Collected Evidence: Collected Evidence: Install speed bumps to reduce vehicle collisions with primates We found no evidence for the effects of installing speed bumps to reduce vehicle collisions with primates on primate populations. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested 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%2F1465https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1465Tue, 17 Oct 2017 14:11:01 +0100Collected Evidence: Collected Evidence: Install sound-proofing insulation between bat roosts and areas occupied by humans within developments We found no studies that evaluated the effects of installing sound-proofing insulation between bat roosts and areas occupied by humans within developments on bat 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%2F1929https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1929Fri, 30 Nov 2018 13:47:18 +0000Collected Evidence: Collected Evidence: Install sound barriers in proximity to bat roosts and habitats We found no studies that evaluated the effects of installing sound barriers in proximity to bat roosts and habitats on bat 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%2F2023https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2023Wed, 05 Dec 2018 18:09:06 +0000Collected Evidence: Collected Evidence: Install physical barriers to prevent trawling One study examined the effects of installing physical barriers to prevent trawling on subtidal benthic invertebrate populations. The study was in the Bay of Biscay (Spain).   COMMUNITY RESPONSE (1 STUDY) Overall community composition (1 study): One before-and-after study in the Bay of Biscay found that one to four years after installing artificial reefs as physical barriers to prevent trawling invertebrate community composition changed. POPULATION RESPONSE (1 STUDY) Overall abundance (1 study): One before-and-after study in the Bay of Biscay found that one to four years after installing artificial reefs as physical barriers to prevent trawling overall invertebrate biomass increased. Echinoderm abundance (1 study): One before-and-after study in the Bay of Biscay found that one to four years after installing artificial reefs as physical barriers to prevent trawling the biomass of sea urchins and starfish increased. Molluscs abundance (1 study): One before-and-after study in the Bay of Biscay found that one to four years after installing artificial reefs as physical barriers to prevent trawling the biomass of gastropods (sea snails), of one species of cuttlefish, and of two species of octopus increased. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2112https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2112Tue, 22 Oct 2019 09:40:04 +0100Collected Evidence: Collected Evidence: Install stormwater traps or grids We found no studies that evaluated the effects of installing stormwater traps or grids 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%2F2203https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2203Tue, 22 Oct 2019 13:14:36 +0100Collected Evidence: Collected Evidence: Install mammal crossing points along fences on farmland Four studies evaluated the effects on mammals of installing mammal crossing points along fences on farmland. Two studies were in Namibia and one each was in the USA and the UK. KEY COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (4 STUDIES) Use (4 studies): A study in the USA found that pronghorn antelopes crossed a modified cattle grid which prevented escape of domestic sheep and cows. A controlled, before-and-after study in Namibia found installing swing gates through game fencing reduced the digging of holes by animals under the fence, whilst preventing large predator entry. A study in the UK found that a vertical-sided ditch under an electric fence allowed access by otters. A before-and-after study in Namibia found that tyres installed as crossings through fences were used by wild mammals and reduced fence maintenance requirements. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2410https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2410Fri, 29 May 2020 12:42:36 +0100Collected Evidence: Collected Evidence: Install non-electric fencing to exclude predators or herbivores and reduce human-wildlife conflict Eight studies evaluated the effects on mammals of installing non-electric fencing to exclude predators or herbivores and reduce human-wildlife conflict. Two studies were in the USA and one each was in Germany, the UK, Spain, China, Tanzania and Kenya. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (8 STUDIES) Human-wildlife conflict (8 studies): Four replicated studies (including three before-and-after studies), in USA, China, Tanzania and Kenya, found that non-electric fencing reduced livestock predation by coyotes, Tibetan brown bears, and a range of mammalian predators. A replicated, controlled study in USA found that a high woven wire fence with small mesh, an overhang and an apron (to deter burrowing) was the most effective design at deterring crossings by coyotes. A replicated, controlled study in Germany found that fencing with phosphorescent tape was more effective than fencing with normal yellow tape for deterring red deer and roe deer, but had no effect on crossings by wild boar or brown hare. Two studies (one replicated, before-and-after, site comparison and one controlled study) in the UK and Spain found that fences reduced European rabbit numbers on or damage to crops. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2415https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2415Mon, 01 Jun 2020 08:22:23 +0100Collected Evidence: Collected Evidence: Install metal grids at field entrances to prevent mammals entering to reduce human-wildlife conflict Two studies evaluated the effects on mammal incursions of installing metal grids at field entrances to reduce human-wildlife conflict. Both of these studies were in the USA. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (2 STUDIES) Human-wildlife conflict (2 studies): One of two replicated studies (including one controlled study), in the USA, found that deer guards (horizontal, ground-level metal grids) reduced entry into enclosures by white-tailed deer whilst the other found that they did not prevent crossings by mule deer or elk. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2440https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2440Tue, 02 Jun 2020 10:19:45 +0100Collected Evidence: Collected Evidence: Install ledges in culverts under roads/railways Three studies evaluated the effects on mammals of installing ledges in culverts under roads or railways. Two studies were in the USA and one was in Portugal. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (3 STUDIES) Use (3 studies): A replicated, controlled study in Portugal found that under-road culverts with ledges were used more than culverts without ledges by two of five mammal species. A before-and-after study in the USA found that installing ledges within under-road culverts did not increase the number or diversity of small mammal species crossing through them, and only one of six species used ledges. A study in the USA found that ledges in under-road culverts were used by nine of 12 small mammal species and ledges with access ramps were used more often than those without. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2523https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2523Mon, 08 Jun 2020 10:50:11 +0100Collected Evidence: Collected Evidence: Install overpasses over roads/railways Twenty-two studies evaluated the effects on mammals of installing overpasses over roads or railways. Seven studies were in Canada, three were in Spain, three were in Australia, two were in Sweden, one each was in the Netherlands, Germany, Croatia and the USA, and three (including two reviews) were conducted across multiple countries. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (4 STUDIES) Survival (4 studies): Four studies (including three before-and-after studies), in Canada, Sweden and Australia, found that overpasses (in combination with roadside fencing) reduced collisions between vehicles and mammals. In two of these studies, data from overpasses and underpasses were combined for analysis. BEHAVIOUR (21 STUDIES) Use (21 studies): Nineteen studies, in North America, Europe and Australia, found that overpasses were used by mammals. A wide range of mammals was reported using overpasses, including rodents and shrews, rabbits and hares, carnivores, ungulates, bears, marsupials and short-beaked echidna. A review of crossing structures in Australia, Europe and North America found that overpasses were used by a range of mammals, particularly larger mammal species. A global review of crossing structures (including overpasses) found that all studies reported that the majority of crossings were used by wildlife. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2526https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2526Mon, 08 Jun 2020 13:33:46 +0100Collected Evidence: Collected Evidence: Install pole crossings for gliders/flying squirrels Seven studies evaluated the effects on gliders/flying squirrels of installing pole crossings. Six studies were in Australia and one was in the USA. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Survival (1 study): A study in Australia found that arboreal marsupials using artificial road crossing structures did not suffer high predation rates when doing so. BEHAVIOUR (6 STUDIES) Use (6 studies): Six studies (five replicated), in Australia and the USA, found that poles were used for crossing roads by squirrel gliders, sugar gliders and Carolina northern flying squirrels. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2546https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2546Tue, 09 Jun 2020 09:20:33 +0100Collected Evidence: Collected Evidence: Install rope bridges between canopies Ten studies evaluated the effects on mammals of install rope bridges between canopies. Eight studies were in Australia, one was in Brazil and one in Peru. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Survival (1 study): A study in Australia found that arboreal marsupials using rope bridges did not suffer high predation rates when doing so. BEHAVIOUR (9 STUDIES) Use (9 studies): Nine studies (including three replicated studies and a site comparison), in Australia, Brazil and Peru found that rope bridges were used by a range of mammals. Seven of these studies found between three and 25 species using rope bridges, one found that that they were used by squirrel gliders and one that they were used by mountain brushtail possums and common ringtail possums but not by koalas and squirrel gliders. One of the studies found that crossing rates were higher over the canopy bridges than at ground level. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2556https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2556Tue, 09 Jun 2020 10:50:37 +0100Collected Evidence: Collected Evidence: Install one-way gates or other structures to allow wildlife to leave roadways Seven studies evaluated the effects on mammals of installing one-way gates or other structures to allow wildlife to leave roadways. All seven studies were in the USA. COMMUNITY RESPONSE (5 STUDIES) Survival (5 studies): Two before-and-after studies (one replicated), in the USA, found that barrier fencing with one-way gates reduced deer-vehicle collisions. One of two studies (one before-and-after and one replicated, controlled), in the USA, found that barrier fencing with escape gates along roads with one or more underpasses reduced moose-vehicle collisions, whilst the other found no reduction in total mammal road casualty rates. A replicated, controlled, before-and-after study in USA found that earth escape ramps reduced mammal road mortalities. POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (4 STUDIES) Use (4 studies): One of two studies (one replicated) in the USA, found that one-way gates allowed mule deer to escape when trapped along highways with barrier fencing, whilst the other found that a small proportion used one-way gates. A replicated, controlled, before-and-after study in the USA found that earth escape ramps were used more often than were one-way escape gates to enable deer to escape highways with barrier fencing. A replicated, controlled study in the USA found that barrier fencing with escape gates and underpasses facilitated road crossings by a range of mammals. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2558https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2558Tue, 09 Jun 2020 11:28:18 +0100Collected Evidence: Collected Evidence: Install signage to warn motorists about wildlife presence Six studies evaluated the effects on mammals of installing signage to warn motorists about wildlife presence. Four studies were in the USA one was in Australia and one was in Canada. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (6 STUDIES) Abundance (1 study): A before-and-after study in Australia found that when wildlife signs were installed along with speed restrictions, rumble strips, reflective wildlife deterrents, wildlife escape ramps and an educational pamphlet, a small population of eastern quoll re-established in the area. Survival (6 studies): Three of five studies (including four controlled and three before-and-after studies), in the USA and Canada, found that warning signs did not reduce collisions between vehicles and deer. The other two studies found that warning signs did reduce collisions between vehicles and deer. A before-and-after study in Australia found that wildlife signs along with speed restrictions, rumble strips, reflective wildlife deterrents, wildlife escape ramps and an educational pamphlet, reduced collisions between vehicles and Tasmanian devils but not eastern quolls. BEHAVIOUR (0 STUDIES) OTHER (2 STUDIES) Human behaviour change (2 studies): Two controlled studies (one also replicated, before-and-after), in the USA, found that signs warning of animals on the road reduced vehicles speeds. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2608https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2608Thu, 11 Jun 2020 16:22:25 +0100Collected Evidence: Collected Evidence: Install overpasses over waterways Two studies evaluated the effects on mammals of installing overpasses over waterways. One study was in the USA and one was in Spain. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (2 STUDIES) Use (2 studies): Two studies (one replicated, one a site comparison) in the USA and Spain, found that bridges and overpasses over waterways were used by desert mule deer, collared peccaries and coyotes and by a range of large and medium-sized mammals. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2628https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2628Fri, 12 Jun 2020 11:38:42 +0100Collected Evidence: Collected Evidence: Install physical supports for planted non-woody plants: freshwater wetlands One study evaluated the effects of installing physical supports for emergent, non-woody plants planted in freshwater wetlands. The study was in the Netherlands. VEGETATION COMMUNITY   VEGETATION ABUNDANCE   VEGETATION STRUCTURE Biomass/plant (1 study): One replicated, controlled study at the edge of a freshwater lake in the Netherlands found that supporting planted bulrushes Scirpus with wire mesh had no significant effect on biomass of individual plants after 1–2 years. Stems/plant (1 study): The same study found that supporting planted bulrushes Scirpus with wire mesh had no significant effect on number of shoots/plant after 1–2 years. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3336https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3336Sun, 11 Apr 2021 16:38:18 +0100Collected Evidence: Collected Evidence: Install physical supports for planted non-woody plants: brackish/saline wetlandsWe found no studies that evaluated the effects of installing physical supports for emergent, non-woody plants planted in brackish/saline wetlands.   ‘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%2F3337https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3337Sun, 11 Apr 2021 16:38:28 +0100Collected Evidence: Collected Evidence: Install physical supports for planted trees/shrubs: freshwater wetlandsWe found no studies that evaluated the effects of installing physical supports for trees/shrubs planted in freshwater wetlands.   ‘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%2F3338https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3338Sun, 11 Apr 2021 16:38:46 +0100Collected Evidence: Collected Evidence: Install physical supports for planted trees/shrubs: brackish/saline wetlandsWe found no studies that evaluated the effects of installing physical supports for trees/shrubs planted in brackish/saline wetlands.   ‘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%2F3339https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3339Sun, 11 Apr 2021 16:39:01 +0100Collected Evidence: Collected Evidence: Install overpasses over roads/railways Five studies evaluated the effects of installing overpasses over roads/railways on reptile populations. Three studies were in Spain, one was a review of studies in Australia, Europe and North America and one study was in Australia. COMMUNITY RESPONSE (1 STUDY) Community composition (1 study): One before-and-after, site comparison study in Australia found that the composition of reptile species on a vegetated overpass was more similar to woodland on one side of the overpass than the other. Richness/diversity (1 study): One before-and-after, site comparison study in Australia found that a vegetated overpass was colonised by two reptile species each year over five years. POPULATION RESPONSE (1 STUDY) Occupancy/range (1 study): One before-and-after, site comparison study in Australia found that a vegetated overpass was colonized by 14 of 23 native reptile species and one non-native reptile species. BEHAVIOUR (4 STUDIES) Use (4 studies): Three of four studies (including two replicated studies and one review) in Spain and Australia, Europe and North America found that overpasses not designed for wildlife were used by lizards and snakes and reptiles. The other study found that overpasses not designed for wildlife were not used by snakes or lizards. Two replicated studies in Spain found that wildlife overpasses were used by lizards and Ophidians (snakes and legless lizards), and one review in Australia, Europe and North America found that one of 10 wildlife overpasses were used by reptiles. One review of road crossing structures in Australia, Europe and North America found that a rope bridge was not used by reptiles. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3510https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3510Tue, 07 Dec 2021 12:26:43 +0000Collected Evidence: Collected Evidence: Install sound barriers in proximity to reptile habitats We found no studies that evaluated the effects on reptile populations of installing sound barriers in proximity to reptile habitats. ‘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%2F3640https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3640Thu, 09 Dec 2021 15:09:25 +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.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust
For a full list of, and information about, our champions:
All Evidence Champions
About our champions, why and how to become one:
Become an Evidence Champion

This website uses Cookies

We use limited Cookies to run the site and to analyse our traffic (none for site vendors). By using this site, you will be providing your consent to our use of Cookies.

Accept & continue