Collected Evidence: Collected Evidence: Install tunnels/culverts/underpass under roads Twenty-five studies evaluated the effects on mammals of installing tunnels, culverts or underpass under roads. Eight studies were in the USA, four were in Australia, four were in Canada, two were in Spain, one each was in Germany, the Netherlands and South Korea and three were reviews with wide geographic coverage. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (3 STUDIES) Survival (3 studies): A study in South Korea found that road sections with higher underpass density did not have fewer wildlife-vehicle collisions. A review found that most studies recorded no evidence of predation of mammals using crossings under roads. A controlled, before-and-after, site comparison study in Australia found that overwinter survival of mountain pygmy-possums increased after an artificial rocky corridor, which included two underpasses, was installed. BEHAVIOUR (23 STUDIES) Use (23 studies): Seventeen of 20 studies (including seven replicated studies and two reviews), in the USA, Canada, Australia, Spain, the Netherlands, and across multiple continents, found that crossing structures beneath roads were used by mammals whilst two studies found mixed results depending on species and one study found that culverts were rarely used as crossings by mammals. One of the studies found that crossing structures were used by two of four species more than expected compared to their movements through adjacent habitats. A controlled, before-and-after, site comparison study in Australia found that an artificial rocky corridor, which included two underpasses, was used by mountain pygmy-possums. A replicated study in Germany found that use of tunnels by fallow deer was affected by tunnel colour and design. A study in the USA found that a range of mammals used culverts, including those with shelves fastened to the sides. Behaviour change (1 study): A controlled, before-and-after, site comparison study in Australia found that after an artificial rocky corridor, which included two underpasses, was installed, dispersal of mountain pygmy-possums increased. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2514https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2514Fri, 05 Jun 2020 10:17:32 +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 barrier fencing along roads Twelve studies evaluated the effects on mammals of installing barrier fencing along roads. Eight studies were in the USA, one each was in Canada, Germany and Brazil and one spanned the USA, Canada and Sweden. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (9 STUDIES) Survival (9 studies): Three controlled studies, in the USA, Germany and Brazil, found that roadside fencing or equivalent barrier systems reduced the numbers of mammals, including wildcats and coypu, killed by vehicles on roads. Two before-and-after studies, in the USA, found that roadside fencing with one-way gates to allow escape from the road, reduced the number of collisions between vehicles and deer. A study in the USA found that a 2.7-m-high fence did not reduce road-kills of white-tailed deer compared to a 2.2-m-high fence. A controlled, before-and-after study in the USA found that barrier fencing with designated crossing points did not significantly reduce road deaths of mule deer. A replicated, controlled, before-and-after study in Canada found that electric fences, (along with an underpass beneath one highway), reduced moose-vehicle collisions. A review of fencing studies from USA, Canada and Sweden, found that longer fencing along roadsides led to a greater reduction of collisions between large mammals and cars than did shorter fence sections. BEHAVIOUR (5 STUDIES) Behaviour change (5 studies): A controlled, before-and-after study in the USA found that 2.3-m-high fencing in good condition prevented most white-tailed deer accessing a highway. A replicated, controlled, before-and-after study in Canada found that electric fences reduced moose access to highways. Three studies (two replicated), in the USA, found that higher fences (2.4–2.7 m) prevented more white-tailed deer from entering highways than did fences that were 2.2 m high, 1.2 m high with outriggers or 1.2–1.8 m high. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2567https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2567Tue, 09 Jun 2020 14:55:48 +0100Collected Evidence: Collected Evidence: Install barrier fencing and underpasses along roads Fifty-five studies evaluated the effects on mammals of installing barrier fencing and underpasses along roads. Twenty-seven were in the USA, nine were in Canada, seven were in Australia, two each were in Spain, Portugal, the UK and Sweden, one each was in Denmark, Germany and Croatia and one was a review covering Australia, Europe and North America. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (15 STUDIES) Survival (15 studies): Eleven of 15 studies (including 12 before-and-after studies and two site comparisons), in the USA, Australia, Sweden and Canada, found that installing underpasses and associated roadside barrier fencing reduced collisions between vehicles and mammals. Three studies found that the roadkill rate was not reduced and one study found that vehicle-mammal collisions continued to occur after installation. BEHAVIOUR (52 STUDIES) Use (52 studies): Seventeen of 18 studies (including 10 before-and-after studies) in the USA, Canada and Sweden, which reported exclusively on ungulates, found that underpasses installed along with roadside barrier fencing were used by a range of ungulate species. These were mule deer, mountain goat, pronghorn, white-tailed deer, elk, moose and Florida Key deer. The other study found that underpasses were not used by moose whilst one of the studies that did report use by ungulates further reported that they were not used by white-tailed deer. Further observations from these studies included that elk preferred more open, shorter underpasses to those that were enclosed or longer, underpass use was not affected by traffic levels and that mule deer used underpasses less than they used overpasses. Thirty-four studies (including four before-and-after studies, seven replicated studies, three site comparisons and two reviews), in the USA, Canada, Australia, Spain, Portugal, the UK, Denmark, Germany, Croatia and across multiple continents, that either studied mammals other than ungulates or multiple species including ungulates, found that underpasses in areas with roadside fencing were used by mammals. Among these studies, one found that small culverts were used by mice and voles more than were larger underpasses, one found that bandicoots used underpasses less after they were lengthened and one found that culverts were used by grizzly bears less often than were overpasses. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2571https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2571Wed, 10 Jun 2020 08:35:55 +0100Collected Evidence: Collected Evidence: Install wildlife warning reflectors along roads Fifteen studies evaluated the effects on mammals of installing wildlife warning reflectors along roads. Nine studies were in the USA, three were in Austalia, two were in Germany and one was in Denmark. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (10 STUDIES) Abundance (1 study): A before-and-after study in Australia found that when warning reflectors were installed (along with speed restrictions, reflective wildlife signs, rumble strips, wildlife escape ramps and an educational pamphlet) a small population of eastern quoll re-established in the area. Survival (10 studies): Five of eight controlled or before-and-after studies in the USA and Germany found that wildlife warning reflectors did not reduce collisions between vehicles and deer. Two studies found that vehicle-deer collisions were reduced by reflectors and one found that collisions were reduced in rural areas but increased in suburban areas. A before-and-after study in Australia found that when warning reflectors were installed (along with speed restrictions, reflective wildlife signs, rumble strips, wildlife escape ramps and an educational pamphlet) vehicle collisions with Tasmanian devils, but not eastern quolls, decreased. A review of two studies in Australia found mixed responses of mammal road deaths to wildlife warning reflectors. BEHAVIOUR (5 STUDIES) Behaviour change (5 studies): Three of four studies (including three controlled studies), in the USA, Denmark and Germany, found that wildlife warning reflectors did not cause deer to behave in ways that made collisions with vehicles less likely (such as by avoiding crossing roads). The other study found that deer initially responded to wildlife reflectors with alarm and flight but then became habituated. A replicated, controlled study in Australia found that one of four reflector model/colour combinations increased fleeing behaviour of bush wallabies when lights approached. The other combinations had no effect and none of the combinations affected red kangaroos. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2591https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2591Thu, 11 Jun 2020 09:30:25 +0100
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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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