Remove/control non-native mammals

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Source countries

Key messages

  • Twenty-five studies evaluated the effects on non-controlled mammals of removing or controlling non-native mammals. Twenty-one studies were in Australia, and one was in each of France, the UK, Equador and the USA.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (24 STUDIES)

  • Abundance (21 studies): Ten of 18 controlled, before-and-after or site comparison studies, in Australia, found that after controlling red foxes, abundances, densities or trapping frequencies increased for rock-wallaby spp., eastern grey kangaroo, woylie,, brush-tail possum, tammar wallaby, chuditch and quenda. Seven studies found mixed results with increases in some species but not others, increases followed by declines or increases only where cats as well as foxes were controlled. The other study found no increase in bush rat numbers with fox control. One of three replicated, before-and-after studies (including two controlled studies), in Australia, France and Ecuador, found that control of invasive rodents increased numbers of lesser white-toothed shrews and greater white-toothed shrews. One study found that Santiago rice rat abundance declined less with rodent control and one found mixed results, with increased numbers of short-tailed mice at one out of four study sites.
  • Survival (1 study): A replicated, controlled study in Australia found that controlling red foxes increased survival of juvenile eastern grey kangaroos.
  • Occupancy/range (3 studies): Three studies (two before-and-after, one controlled), in the UK and Australia, found that after controlling non-native American mink, red foxes and European rabbits, there were increases in ranges or proportions of sites occupied by water vole, common brushtail possum, long-nosed potoroo and southern brown bandicoot and four native small mammal species.

BEHAVIOUR (1 STUDY)

  • Behaviour change (1 study): A before-and-after study in the USA found that following removal of feral cats, vertebrate prey increased as a proportion of the diet of island foxes.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A replicated, controlled, before-and-after study in 1979–1990 in four granite outcrop sites in Western Australia, Australia (Kinnear et al. 1998) found that after red fox Vulpes vulpes control, numbers of rock-wallabies Petrogale lateralis increased. Results were not tested for statistical significance. In the two sites where fox control was carried out, there were more rock-wallabies after eight years of fox control (50–116 wallabies) than prior to fox control (10–29 wallabies). Over the same period, in the two sites where there was no fox control, wallaby populations declined (after: 0–13; before 7-32). Foxes were initially controlled by shooting and, later, by baiting with fowl eggs dosed with 4.5 mg of 1080 poison. Baiting occurred during the dry seasons of 1980–1983. In 1986–1990, baits were laid along tracks every four to five weeks. Rock-wallabie numbers were estimated by the frequency of recaptures in 1979, 1986 and 1990.

    Study and other actions tested
  2. A controlled, before-and-after study in 1993–1995 in four mountain forest sites in the Australian Capital Territory, Australia (Banks 1999) found that after baiting with poison to control invasive red foxes Vulpes vulpes, bush rat Rattus fuscipes numbers did not increase. Bush rat numbers at the end of the study were higher in sites with fox control (11–14 animals) compared to without (6–8 animals). However, in sites with control, bush rat numbers were similar 22 months after fox control began (11-14 animals) compared to immediately beforehand (11-12 animals; results not statistically tested). Four 10–28 km2 sites were studied in Namadgi National Park. Fox control started in two sites in July 1993 using 1080 poison bait, and in two sites there was no fox control. Red fox numbers in baited sites were reduced from 2.8–3.4/km to <0.5/km in six months and to almost zero over the following 12 months, while fox density remained stable and approximately five times higher in unbaited sites. Bush rats were monitored on two plots in unbaited sites (>2 km apart) and in one plot in baited sites. In total, two trap lines (25 m apart) of 15 Elliott live traps were set at 10–14 m intervals for three consecutive nights, every two months from June 1993 to March 1995 (6,480 trap nights). Foxes were surveyed using spotlights along transects.

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  3. A replicated, controlled study in 1993­–1995 in four open grassy sites in the Australian Capital Territory, Australia (Banks et al. 2000) found that controlling invasive red foxes Vulpes vulpes increased eastern grey kangaroo Macropus giganteus population growth rates and juvenile survival. Kangaroo population growth rates were higher in fox control sites than in uncontrolled sites (data reported as statistical model outputs). In sites with fox control the proportion of females with pouch young was similar at the end of pouch emergence (0.87-0.88 females with young) compared to at the beginning (0.78-0.80 females with young), whereas in sites without fox control, the proportion of females with young declined by 50% by the end of the pouch emergence phase (0.55-0.61 females with young) compared to the beginning (0.94-0.97 females with young). Foxes were removed from two sites within Namadgi National Park using 35 g FOXOFF baits (containing 0.3 mg of 1080 poison). Baiting commenced in July 1993 and reduced fox numbers from 2.8–3.4/km to <0.5/km within six months and to almost zero over the following 12 months. Fox numbers in two unbaited sites remained relatively constant (0.8–2/km). Kangaroos were counted in four sites (two with fox control and two without) one hour before dusk from a slow moving car (<5 km/h) along 1.5–2 km transects (400–700 m wide). Surveys were conducted in August, October and December 1993 and then monthly until March 1995. Transects were surveyed twice each survey period.

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  4. A replicated, controlled, before-and-after study in 1999 at six shrub and grassland sites on an island in Western Australia, Australia (Moro 2001) found that baiting to control invasive house mice Mus domesticus increased the density of short-tailed mice Leggadina lakedownensis in one out of four comparisons. Twenty-two days after baiting, the minimum abundance of short-tailed mice was higher in one site with bait deployed every 10 m than before baiting (12.7 vs 7.0 mice). Short-tailed mouse numbers were low in all other sites (baited and unbaited) and were similar after baiting compared to before (see original paper for details). House mice numbers declined on all baited sites (pre-baiting: 5.8-6.2 mice/ha; post baiting: 2.5-2.7 mice/ha). Six grids were established in individual sites at least 1 km apart in May 1999. Two sites were baited with ‘Talon’ (15-g wax blocks containing 0.005% brodifacoum) at 10 m intervals (117 bait stations/grid), two were baited at 20 m intervals (45 bait stations/grid) and two were unbaited. Bait was replenished every two days for seven days and then again on the fourteenth day. Each site had 25 trap stations arranged in a 5 x 5 pattern, each with one pitfall trap and associated 5 m drift-fencing and one Elliott trap. Sites were monitored for two nights before baiting and up to 22 nights after baiting.

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  5. A before-and-after, controlled study in 1990–1994 in three sites in Western Australia, Australia (Risbey et al. 2000) found that where both cats Felis catus and foxes Vulpes vulpes were controlled, captures of small mammals increased but where only foxes were controlled, they decreased. Combined fox and cat control doubled small mammal abundances (after: 93; before: 42 individuals captured), but counts fell by 80% where only foxes were controlled (after: 7; before: 55 individuals captured). Small mammal abundances remained similar where no predators were controlled. See original paper for full results. In 1991, a mainland peninsula was divided in three areas in which 1) both cats and foxes were controlled by using an electrified fence, poison baiting (dried meat or cat food with 4.5 mg 1080 poison or via secondary poisoning by poisoning rabbits Oryctolagus cuniculus), and trapping or shooting (12 km2), 2) foxes were controlled by baiting (120-200 km2) but cats were not targeted or 3) no control occurred. Predators were surveyed over 3-4 nights in vehicles using spotlights (transect length: 7.5-20 km). Small mammals were monitored with six pitfall-trap grids in each area. Each grid had eight pitfall traps, 30–50 m apart. Sampling was conducted over three consecutive days in March–April and June–July in 1990–1994 in predator control areas and 1992–1994 in the area without predator control.

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  6. A before-and-after, site comparison study in 1979–1990 on two islands in Western Australia, Australia (Kinnear et al. 2002) found that following control of red foxes Vulpes vulpes using poisoned baits, numbers of Rothschild’s rock-wallaby Petrogale rothschildi increased. Results were not tested for statistical significance. After six years of fox control, wallaby numbers were higher (8.8 sightings/hour) than before control (0.3 sightings/hour). During the same period, numbers remained stable on a nearby fox free island (before: 18.7; after: 19.2 sightings/hour). Foxes were controlled by baiting on Dolphin island (3,203 ha), Dampier Archipelago. Meat baits or intact fowl eggs, laced with 1080-poison, were deployed manually in limited areas in October 1980 and May 1981 and then deployed aerially on a larger scale, three times from September 1984 to October 1989. Foxes were also controlled on neighbouring islands and the nearby mainland to prevent immigration (see original paper for details). In 1979–1980 and in 1990, spotlight counts of rock-wallabies were carried out on both Dolphin Island and the nearby fox-free Enderby Island (3,290 ha). Surveys were conducted on foot using a long range 100-W spotlight (1979-1980: 10; 1990: 4 hours of surveying). No fox abundance data are provided.

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  7. A before-and-after study in 1979–1998 in a forest reserve in Western Australia, Australia (Kinnear et al. 2002) found that after baiting with poison to control red foxes Vulpes vulpes, numbers of woylies Bettongia penicillata, brush-tail possums Trichosurus vulpecula and tammar wallabies Macropus eugenii increased. Results were not tested for statistical significance. After eight years of fox control, numbers were higher than before control for woylies (after: 1.3; before: 0.0 sightings/hour, after: 0.2-0.3; before: 0.0 individuals/trap night), brush-tail possums (after: 7.7; before: 0.4 sightings/hour) and tammar wallabies (after: 9.4; before: 0.4 sightings/hour). Numbers of tammar wallabies continued to increase up to 14 years after the start of fox control (40 sightings/hour). Foxes were controlled by baiting from 1984 in Tutanning Nature Reserve (2,200 ha). Baits (1080-poison meat baits or intact fowl eggs) were deployed monthly. Mammals were surveyed in 1979–1998 by repeated spotlight counts along 50 circuits near to the boundary of the reserve (circuit length is not provided). Woylies were also monitored using cage traps at 100 m intervals on 1 km-long transects (380 trap nights in 1979; 322 trap nights in 1984; 320 trap nights in 1989; 266 trap nights in 1992). Spotlight searches were conducted using long range 100-W lights.

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  8. A before-and-after study in 1987-1998 in a forest reserve in Western Australia, Australia (Kinnear et al. 2002) found that after baiting with poison to control red foxes Vulpes vulpes, numbers of brush-tail possums Trichosurus vulpecula and tammar wallabies Macropus eugenii increased. Results were not tested for statistical significance. Three years after the start of fox control, numbers of tammar wallaby (105.2 sightings/hour) and brush-tail possums (10.5 sightings/hour) increased compared to prior to fox control (wallabies: 4.8 sightings/hour; brush-tail possums: 0 sightings/hour). Numbers of tammar wallabies (61.7 sightings/hour) and brush-tail possums (6.3 sightings/hour) remained higher nine years after fox control started. Foxes were controlled using poison baits (1080-poison meat baits or intact fowl eggs) from 1989 in a separate annex of Tutanning Nature Reserve (114 ha). Mammals were surveyed in 1987, 1992 and 1998 by repeated spotlight counts using long range 100 W lights.

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  9. A before-and-after, site comparison study in 1985–1996 in a forest reserve in Western Australia, Australia (Kinnear et al. 2002) found that after baiting with poison to control red foxes Vulpes vulpes, numbers of brush-tail possums Trichosurus vulpecula and tammar wallabies Macropus eugenii increased and translocated woylies Bettongia penicillata were still present. Results were not tested for statistical significance. Numbers of brush-tail possums and tammar wallabies were higher in an area where foxes had been baited for seven years than in an area baited for three years (brush-tail possums: 9.1 vs 0.3; tammar wallabies: 1.8 vs 0.0). Four years after translocation, woylies, which were absent prior to fox control, were found to number eight individuals on the east side and 59 on the west side. Foxes were controlled by baiting from 1985 in the east area of the Boyagin Nature Reserve (4,780 ha) and from 1989 in the west. Baits (1080-poison meat baits or intact fowl eggs) were deployed monthly. Mammals were surveyed in 1989-1992 by repeated spotlight counts using long range 100-W lights and cage traps at 100 m intervals on 1 km-long transects in 1992 and 1996 (150 trap nights/area). In total 40 woylies were translocated in 1992 (20 released in the east and 20 in the west area).

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  10. A before-and-after study in 1970–1992 in a forest reserve in Western Australia, Australia (Kinnear et al. 2002) found that after baiting with poison to control red foxes Vulpes vulpes, numbers of woylies Bettongia penicillata and brush-tail possums Trichosurus vulpecula increased, but tammar wallabies Macropus eugenii numbers did not. Results were not tested for statistical significance. Three years after the start of widespread fox control, overall numbers of individuals were higher than before control for woylies (after: 27.7; before: 1.2 sightings/hour) and brush-tail possums (after: 22.3; before: 2.8 sightings/hour) but tammar wallaby sightings remained infrequent (0 sightings/hour). Ten years after baiting began in a restricted area where fox control was tested before widespread control commenced, numbers of individuals were higher than before control for woylies (after: 23; before: 0.4 sightings/hour), brush-tail possums (after: 9.9; before 2.0 sightings/hour) and tammar wallabies (after: 1.23; before: 0.5 sightings/hour). Foxes were controlled by baiting in a restricted area from 1982, and across the whole reserve from 1989 in a 12,000 ha forest fragment in Dryandra Woodlands. Baits (1080-poison meat baits or intact fowl eggs) were deployed monthly. Mammals were surveyed before fox control in 1970-1971 (75 hours), once the restricted area baiting trial had commenced in 1987 (5 hours) and 1989 (8 hours), and after baiting had been extended to the whole reserve in 1990 (4.5 hours) and 1992 (5.7 hours). Repeated spotlight surveys were conducted along 49 routes using long range 100-W lights (route length is not provided). Woylies were also trapped in cages (see original paper for details).

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  11. A site comparison study in 1991–1998 in a national park in Western Australia, Australia (Kinnear et al. 2002) found that after baiting with poison to control red fox Vulpes vulpes, numbers of brush-tail possums Trichosurus vulpecula and tammar wallabies Macropus eugenii increased. Results were not tested for statistical significance. Four years after the start of fox control, brush-tail possum and wallaby numbers were higher in areas where foxes were controlled than in areas where they were not (possums: 19.3 vs 1.1 sightings/hour; wallabies: 5.47 vs 0.0 sightings/hour). Trapping success rates for brush-tail possums were higher in baited compared to unbaited areas and increased every year in fox control areas (see original paper for details). Foxes were controlled in half of the 329,000-ha Fitzgerald River National Park. The other half of the park was left unbaited. Baits (dried meat with 4.5 mg of 1080 poison) were distributed aerially twice a year in 1991-1995 at a density of six baits/km2. Supplementary bait was also distributed in some areas by vehicle in 1995-1996. Mammals were surveyed by repeated spotlight surveys using long range 100-W lights (unbaited area: 9.4 hours in 1994-1995; baited area: 17.1 hours in 1993-1996) and trapping (possums only) in 1994-1998 (4 km long trap lines with 40 traps set at 100 m intervals).

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  12. A replicated, site comparison study (year not stated) in eight swamp shrubland sites in Western Australia, Australia (Hayward et al. 2003) found that controlling non-native red foxes Vulpes vulpes had mixed effects on quokka Setonix brachyurus populations. Results were not tested for statistical significance. In 10 of 15 comparisons, sites where foxes were controlled had higher quokka densities than did areas where foxes were not controlled (0.1–4.3 vs 0 quokkas/ha). In five of 15 comparisons, there were fewer or equal numbers of quokkas in fox-control and uncontrolled sites (0–0.07 vs 0–1.1 quokkas/ha). Starting in an unspecified year, once a month, at five sites, meat laced with 1080 poison was laid at 100-m intervals. At three sites, no bait was laid. Five baits/km2 were also dropped from aircraft in the area surrounding baited sites. In each site two wire cage traps were placed every 50–100 m along a stream. One trap, measuring 0.90 × 0.45 × 0.45 m, was baited with apples. The other trap, measuring 0.59 × 0.205 × 0.205 m, was baited with peanut butter, rolled oats, honey, and pilchards. Quokkas were caught and released over an eight-day period at each site and were fitted with transponder microchips to allow individual identification.

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  13. A replicated, before-and-after study in 1994–2004 on five temperate oceanic islands in northern France (Pascal et al. 2005) found that after the eradication of Norway rats Rattus norvegicus, the abundance of lesser white-toothed shrews Crocidura suaveolens increased on four islands and greater white-toothed shrews Crocidura russula increased on one island. No statistical analyses were performed. Ten years after rat eradication, the abundance of lesser white-toothed shrews on four islands was greater than that before rat eradication (after: 0.09–0.14 shrews/trap night; before: 0.00–0.01). One and two years after rat eradication on a further island, the abundance of greater white-toothed shrews was greater than that before rat eradication (after: 0.31 shrews/trap night; before: 0.02). In total, Norway rats were eradicated from seven islands (0.2–21 ha) in 1994-2002 by trapping and baiting with anticoagulant rodenticide (Bromadiolone©) or using strychnine poisoning (one island in 1951). Monitoring results from five islands are reported here. Small mammal sampling was conducted with 7–269 trap stations at 6-30 m intervals in 1994-2004. Each station had two live traps and was checked daily for 3–7 days.

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  14. A before-and-after study in 1997–2005 along a river in Norfolk, UK (Thompson 2006) found that after controlling invasive American mink Mustela vison, the proportion of sites occupied by water voles Arvicola terrestris increased. Results were not tested for statistical significance. After two years of mink control, a higher proportion of sites were occupied by water voles (27 of 59 sites, 46%) than before control (21 of 62 sites, 35%). No mink signs were found at any survey sites in 2005. Over 280 mink were trapped and euthanised along the River Wensum and its tributaries using traps on banks (1.3–1.6 mink/traps over 3 years, 262 individual mink) and rafts (1.8–2.2 mink/raft over 2 years, 18 individual mink). Between 200 and 220 bank traps (in 2004-2006) and 5-10 raft traps (in 2004-2005) were deployed. Raft traps were arranged in clusters of two to four with clusters at 1–5 km intervals. Water voles were surveyed in 1997 (62 sites), 2003 (60 sites) and 2005 (59 sites) by searching for water vole signs (e.g. latrines, burrows) along 500 m sections of waterway.

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  15. A before-and-after study in 1995­–2002 in heath and forest habitats in New South Wales, Australia (Dexter et al. 2007) found that after controlling invasive red foxes Vulpes vulpes, one of seven mammal species increased. After four years of fox control, more common ringtail possums Pseudocheirus peregrinus were detected than before control (after: 1.8; before: 0.7 individuals/100 m). However, numbers remained similar between fox control and pre-control periods for long-nosed bandicoots Perameles nasuta (1.5 vs 0/transect), bush rats Rattus fuscipes (1.5 vs 0/transect), brown antechinus Antechinus stuartii (3.8–7.6 vs 3.2-3.6/transect), sugar gliders Petaurus breviceps (0.1–0.3 vs 0.1-0.2/100 m), black rats Rattus rattus (0.9–3.9 vs 2.6-5.8/transect) and common brushtail possum Trichosurus vulpecula (0.1–0.3 vs 0.0-0.1/100 m). Control, initiated in 1996, was performed over two weeks, in March and August, using FOXOFF® baits containing 3 mg of 1080 poison. Baits were placed 300–900 m apart. Terrestrial mammals were surveyed two years prior to fox control starting (1995-1996) and up to six years afterwards (in 1999, 2000, 2002). Trapping was over four nights between January and March, along five transects, using 20–25 Elliott live traps/transect and 3–4 possum traps/transect, set 20 m apart. Arboreal mammals were surveyed one year prior to fox control starting (1995) and up to 6 years afterwards (in 1996, 1999, 2000, 2002), along five 500-m-long spotlight transects, 1–2 hours after dark.

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  16. A site comparison study in 1999–2003 in New South Wales, Australia (Dexter et al. 2007) found that controlling invasive red foxes Vulpes vulpes increased abundances of four out of five small mammal species. After four years of fox control, numbers of brown antechinus Antechinus stuartii, bush rat Rattus fuscipes, black rat Rattus rattus and long-nosed bandicoot Perameles nasuta, but not of common brushtail possum Trichosurus Vulpecula, were higher than in a site where foxes were not controlled (antechinus: 35 vs 17; bush rat: 29 vs 1; black rat: 1 vs 0; bandicoot: 3 vs 0; possum: 0 vs 4; results not tested for statistical significance). At Booderee National Park, fox control was conducted twice a year between 1999 and 2003 in March and August, using 3 mg 1080 FOXOFF® poison baits, 300–1,000 m apart. No control occurred at Jervis Bay National Park. In both parks, mammals were surveyed over five days in May 2003, along eight 120 m transects, using six Elliott live traps, three possum cage traps and three wire bandicoot traps, spaced 10 m apart. Transects were located at least 500 m apart.

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  17. A randomized, replicated, controlled, before-and-after study in 2002–2003 in arid shrubland on an island in Ecuador (Harris & Macdonald 2007) found that control of invasive black rats Rattus rattus reduced the rate of seasonal declines in the abundance of Santiago rice rats Nesoryzomys swarthi. Rice rat abundance declined in all sites regardless of black rat control (with control: from 11 to 8-9; without control: from 18-19 to 11-12 rats), but the rate of decline was slower in sites where black rats were controlled (data presented as statistical model outputs). The rate of immigrating female rice rats was higher where black rats were controlled (data presented as statistical model outputs). Black rat numbers decreased more in sites with black rat control (from 18 to 1 rat) compared to sites without black rat control (from 14 to 3 rats). Three sites were selected in Santiago Island, Galapagos. In each site, two trapping grids were set up (98 traps set in pairs at 30 m intervals), in one grid all black rats caught were euthanised and in the other black rats were released after capture. Six trapping sessions were carried out between December 2002 and September 2003 in which each site was trapped for five nights. Additional trapping was conducted 8–10 days after the normal trapping to remove “immigrant” black rats. Supplementary food (5 kg of rolled oats, 750 ml of vegetable oil and 600 g of peanut butter) was distributed in each site every six days.

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  18. A before-and-after study in 1980–2005 across an area of former bauxite mines in jarrah forest of Western Australia, Australia (Nichols & Grant 2007) found that controlling non-native red foxes Vulpes vulpes on restored mine areas resulted in increased abundance of chuditch Dasyurus geoffroii, quenda Isoodon obesulus and brushtail possum Trichosurus vulpecula. Results were not tested for statistical significance. Chuditch were caught in 0.2% of traps immediately after fox removal compared to none before, and in 1.4% of traps six years later. Quenda were caught in 2.7% of traps immediately after fox removal compared to none before, but they were also absent six years after fox removal. Brushtail possum were caught in 2.3% of traps six years after fox removal, compared to up to 0.5% before. Control of foxes, using poisoned baits, was carried out from 1994 and fox sightings decreased from 15 that year to none in 1999 and 2000. Mined areas were revegetated using various techniques. Mammals were monitored using wire cage traps, large and medium aluminium box traps and pit traps in 1980, 1993, 1997 and 2005.

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  19. A replicated, paired sites, controlled, before-and-after study in 1997–2003 in six forest sites in Australia (Dexter & Murray 2009) found that controlling invasive red foxes Vulpes vulpes increased overall native mammal abundance and abundances of three out of five species. The average number of trapped mammals was higher in fox-control (11.0) than in non-control sites (5.2). Average numbers of individuals trapped/session were higher in fox-control than in non-control sites for long-nosed potoroos Potorous tridactylus (5.1 vs 2.3), southern brown bandicoots Isoodon obesulus (2.3 vs 1.2) and common brushtail possums Trichosurus vulpecula (3.1 vs 1.0), but not for ringtail possums Pseudocheirus peregrinus or long-nosed bandicoots Perameles nasuta (numbers not given). Increases in abundance over time were found for long-nosed potoroos and ringtail possums, but not for southern brown bandicoots, common brushtail possums or long-nosed bandicoot (results from statistical models). In 1999–2003, foxes were controlled in three out of six forest sites (7,000–16,500 ha) and no control was conducted in the remaining three sites. From February 1999, baits (Foxoff Econbaits, containing 3 mg of 1080 poison) were buried at 15 cm depth every four weeks, at 1-km intervals. At each site, native mammals were surveyed over seven nights, along an 18-km transect, using 60 baited traps, set at 300-m intervals. Trapping was conducted twice before fox-control started (1997–1998) and 12 times after control started (July 1999–May 2003).

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  20. A replicated, before-and-after study in 1979–2007 at four sites in Western Australia, Australia (Kinnear et al. 2010) found that controlling non-native red foxes Vulpes vulpes resulted in an increase in the number of rock wallabies Petrogale spp. At all four sites, 10–24 years after fox control began, rock wallaby populations were higher (33–300 animals), than before fox control began (1–32 animals). Starting in 1982, baits containing 1080 poison were laid monthly around four wildlife reserves. At each site, where there were signs of rock wallabies, 30 live traps were baited with apples over a three-day period. Traps were set each evening and checked at dawn, in December–April and February–March of 1979–2007. All rock wallabies caught were tagged, weighed, and released near their capture site.

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  21. A replicated, controlled study in 2005­–2013 in six forest areas in Australia (Robley et al. 2014) found that after using poison bait to control invasive red foxes Vulpes vulpes, occupancy rates of common brushtail possum Trichosurus vulpecula, long-nosed potoroo Potorous tridactylus and southern brown bandicoot Isoodon obesulus increased. The number of sites occupied by common brushtail possum (51), long-nosed potoroo (20) and southern brown bandicoot (25) was higher in areas where foxes were controlled than in other areas (common brushtail possum: 44; long-nosed potoroo: 7; southern brown bandicoot: 13). Six areas with no previous fox control where selected. From October 2005–November 2013, foxes were baited in three areas (4,703–9,750 ha) using FoxOff® (containing 3 mg of 1080 poison). Every 1 km, one bait was buried at a depth of 10 cm and replaced fortnightly. Three other areas (4,659–8,520 ha) were left unbaited. In each of the six areas, mammals were monitored annually at 40 sampling sites using hair tubes. Tubes were set for four days in spring 2005 and 2008–2013 and winter 2006 and 2007, and species were identified from hairs.

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  22. A replicated, controlled, before-and-after study in 1980–2012 in four mixed eucalyptus woodland and shrubland in southern Australia (Sharp et al. 2014) found that after control of invasive red foxes Vulpes vulpes, population growth rates of yellow-footed rock-wallabies Petrogale xanthopus increased. In the two populations exposed to fox control, rock-wallaby population growth rates were higher after fox control commenced than before (data presented as statistical model outputs). Over the same time periods, rock-wallaby population growth rates were similar in colonies where foxes were not controlled (data presented as statistical model outputs). In New South Wales, the number of rock-wallabies counted increased two years after fox control began (at start of fox control: 7; after: 16 animals), while in the site without fox control numbers remained similar. Two sites in New South Wales and two in South Australia were studied. In each state, foxes were controlled in one site and not controlled in the other site. Baiting strategy differed by location (see original paper for details). Bait stations (219 in New South Wales and 100 in South Australia) were baited using Foxoff Econobaits® or fresh or dried meat laced with 1080 poison. Baits were deployed from June 1995 in New South Wales and from June 2004 in South Australia. Wallabies were surveyed annually, over three mornings in the winter months, from a helicopter. Surveys were conducted in 1980–2001 (New South Wales) and 2000–2012 (South Australia).

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  23. A replicated, before-and-after study in 1970–2009 in two forest sites in Western Australia, Australia (Marlow et al. 2015) found that controlling invasive red foxes Vulpes vulpes initially increased the abundance of woylies Bettongia penicillata, but woylie numbers returned to pre-control levels after about 25 years. Results were not tested for statistical significance. After 25 years of fox control, the trapping success of woylies (caught in 3–8% of traps from 2002–2006) was only marginally higher than pre-control levels (2–3% from 1970–1975). However, trapping success had increased up to 28–65% during the first 20 years after the start of fox control. Between April 2006 and October 2009, more woylies were killed by cats Felis catus (65%) than by foxes (21%). Foxes were controlled from the mid-1970s at two reserves (2–6,800 ha) by baiting (either dry meat with 3 mg of 1080 poison or Pro-baits) with 5 baits/km2 every four weeks. No details about long-term woylie trapping are provided. Between April 2006 and October 2009, 146 woylies were radio-collared, of which 89 died. Cause of death was determined by DNA analysis and predation characteristics.

    Study and other actions tested
  24. A before-and-after study in 1970–2014 in an arid region in South Australia, Australia (Pedlar et al. 2016) found that control of invasive European rabbits Oryctolagus cuniculus, using rabbit hemorrhagic disease virus, increased the area occupied by four native small mammal species. The extent of occurrence and area of occupancy (both expressed in thousands of km2) was greater after outbreaks of rabbit hemorrhagic disease than before for spinifex hopping mouse Notomys alexis (extent: 276–356 vs 180; area: 7–8 vs 3), dusky hopping mouse Notomys fuscus (extent: 105–130 vs 23; area: 6–11 vs 2), plains mouse Pseudomys australis (extent: 217–252 vs 63; area: 4–6 vs 2) and crest-tailed mulgara Dasycercus cristicauda (extent: 98–133 vs 1; area: 12–13 vs 1). After the first virus outbreak, rabbit abundance decreased by 85% (raw data not provided) in one site and from 139 to 22 rabbits/km2 in the other site. Cat Felis catus and fox Vulpes vulpes numbers followed rabbit population trends. Occurrence records over a 615,000 km2 region were compiled from published sources and divided into periods covering before the outbreak (1970–1995) and after first and second outbreaks (1996–2009 and 2010–2014). Area of occupancy was calculated from occupied 10 × 10 km grid squares. Extent of occurrence was calculated from minimum convex polygons around species records. Rabbit abundance was monitored in two long-term study sites using spotlight transects.

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  25. A before-and-after study in 2006–2012 of scrubland on an island in California, USA (Cyper et al. 2017) found that following removal of feral cats Felis catus, vertebrate prey increased as a proportion of the diet of island foxes Urocyon littoralis. The frequency of deer mice Peromyscus maniculatus in fox scats was higher after cat removal (40%) than before (11%). The same pattern held for birds (after: 12% of scats; before: 6% of scats). Lizard frequency in fox scats was not significantly higher after cat removal (10%) than before (5%) and there were not significant changes in frequencies of arthropods, snails or fruit. Authors indicated that increased deer mouse and bird frequency suggests that foxes and cats had been competing for prey. However, fox abundance was more linked to precipitation levels, and declined over the study period. On a 5,896-ha island, feral cats were eradicated in 2009–2010. Fox scats collected before cat removal (1,180 scats, autumn 2006–summer 2009) and after removal (508 scats, autumn 2010–summer 2012) were analysed for food remains.

    Study and other actions tested
Please cite as:

Littlewood, N.A., Rocha, R., Smith, R.K., Martin, P.A., Lockhart, S.L., Schoonover, R.F., Wilman, E., Bladon, A.J., Sainsbury, K.A., Pimm S. and Sutherland, W.J. (2020) Terrestrial Mammal Conservation: Global Evidence for the Effects of Interventions for terrestrial mammals excluding bats and primates. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.

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Terrestrial Mammal Conservation

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Terrestrial Mammal Conservation
Terrestrial Mammal Conservation

Terrestrial Mammal Conservation - Published 2020

Terrestrial Mammal Conservation

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