Protect habitat: All reptiles (excluding sea turtles)

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

Study locations

Key messages


  • Richness/diversity (5 studies): Three of five studies (including two replicated, site comparison studies) in the USA, South Africa, Australia, Pakistan and Mexico found mixed effects of protected areas on reptile species richness and combined reptile and amphibian species richness. The other two studies found that protected areas had higher reptile species richness than unprotected farmland.


  • Abundance (13 studies): Six of 11 studies (including five replicated, site comparison studies) in the USA, Canada, Hong Kong, Mexico, Australia, South Africa, Argentina, the border of Zambia and Zimbabwe and Pakistan found that protected areas had a higher abundance of reptiles, tortoises, Nile crocodiles and combined reptiles and amphibians than areas with less or no protection. Four studies found mixed effects of protection on the abundance of reptiles and big-headed turtles. The other study found that water bodies in protected areas had fewer eastern long-necked turtles than those in suburban areas. One site comparison study in Brazil found that areas with community-based management of fishing practices, which included protecting river turtle nesting beaches, had more river turtles than areas that did not manage fishing practices. One site comparison study in Madagascar found that the abundance of different sized radiated tortoises in a protected area was more similar to that of an exploited population than to an unexploited population.
  • Occupancy/range (2 studies): One replicated, site comparison study in Argentina found that Argentine tortoises were found in one of two protected areas and two of three unprotected areas. One before-and-after study in Brazil found that most reptile species were still present 20 years after an area was protected.
  • Survival (2 studies): One replicated, randomized, site comparison study in the USA found that in areas with greater protections, survival of Agassiz’s desert tortoises was higher than in areas with less protections. One replicated, site comparison study in Spain found that roads running through protected areas had more reptile road deaths than roads in unprotected areas.
  • Condition (4 studies): Two of three site comparison studies (including one replicated study) in the USA, Australia and Hong Kong found that protected areas had larger red-eared sliders and big-headed turtles compared to areas where harvesting was allowed or was thought to be occurring illegally. The other study found that eastern long-necked turtles in protected areas grew slower and were smaller than turtles in suburban areas. One site comparison study in Madagascar found that radiated tortoises in a protected area had similar genetic diversity compared to populations outside of the protected area.


  • Use (1 study): One replicated study in the USA found that a protected area was used by common chuckwallas.

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, site comparison study in 1990–1991 in eight swamps and wetlands in southern Louisiana and western Mississippi, USA (Close & Seigel 1997) found that sites protected from turtle harvesting and human disturbance had larger red-eared sliders Trachemys scripta elegans compared to harvested sites. Both male and female sliders in unharvested sites were larger (male: 19 cm carapace length; female: 23) than in harvested sites (17, 18). While 24–28% of female turtles in unharvested sites were 24–28 cm long, there were no female turtles >22 cm long in harvested sites. In 1990–1991, turtles were captured from three protected (no public access or turtle harvesting), three public access (public access and no commercial harvesting) and two harvested sites (active commercial harvest). Turtles in protected and public access sites were trapped in baited hoop nets. Turtles in harvested sites were trapped by local hunters or purchased from local fish markets.

    Study and other actions tested
  2. A replicated, site comparison study in 1994–1996 in desert shrub and grassland in south-central California, USA (Brooks 1999) found that lizard abundance and species richness was higher or similar inside a fenced protected area compared to outside depending on survey month and site. Lizard abundance was higher in three of six survey comparisons in a fenced protected area (4–10 lizards/transect) compared to outside of it (2–4 lizards/transect) but similar in the remaining three comparisons (inside: 2–5 lizards/transect; outside: 1–3 lizards/transect; see original paper for details). Lizard species richness was higher in one of six comparisons inside the protected area (2 species/transect) compared to outside of it (1 species/transect) but similar in the remaining five comparisons (inside: 2–3 species/transect; outside: 1–3 species/transect; see original paper for details). In 1994, two sites were selected near the north-eastern and southern boundary of the Desert Tortoise Research Natural Area (where off-road vehicles were prohibited from 1973, sheep grazing prohibited from 1978 and the boundary was fenced in 1980). Two 2.25 ha plots were established/site: one ≥400m inside the boundary and one outside the boundary (used by off-road vehicles until 1980 and grazed by sheep until 1994). In each plot, lizards were surveyed using 1.25 km transects in July 1994 and May and July 1995 (six surveys/site).

    Study and other actions tested
  3. A replicated, before-and-after study in 1972–1973 and 2001–2002 in forest and wetlands in Ontario, Canada (Browne & Hecnar 2007) found that decades of habitat protection had mixed effects on capture rates of native species and one introduced species was newly recorded. Results were not statistically tested. Thirty years after a first survey, capture rates tended to be higher for northern map Graptemys geographica (2002–2003: 0.004 individuals/hoop net night vs. 1972: 0.002) and stinkpot Sternotherus odoratus turtles (0.005 vs. 0.004). However, captures tended to be lower in 2002–2003 for painted Chrysemys picta (0.143 vs. 0.192), Blanding’s Emydoidea blandingii (0.01 vs. 0.054), snapping turtles Chelydra serpentina (0.1 vs. 0.174) and spotted turtles Clemmys guttata (0 vs. 1 individual). Two spiny softshell Apalone spinifera and three introduced pond slider turtles Trachemys scripta were observed for the first time in 2002–2003. Turtle abundances were monitored in a 16 km2 heavily trafficked National Park (gazetted in 1918, designated a Ramsar site in 1987, up to 500,000 visitors/year) in 1972–1973 and 2002–2003 using similar methods. Turtles were trapped using hoop (2002–2003: 3,237 hoop net trap nights; 1972: 522), basking and wire cage live traps as well as hand captures for two months in spring each year. In 2001–2002, all turtles were weighed, measured, sexed, and individually marked before release. Reported catch/trap nights above are for hoop net captures only.

    Study and other actions tested
  4. A site comparison study in 2007 in dry tropical forest in southeast Madagascar (Rioux et al. 2009) found that within a protected area, a population of radiated tortoises Astrochelys radiata had similar levels of genetic diversity as populations outside the protected area, but a size class distribution more similar to that of an exploited than unexploited population. Genetic diversity of the population within the protected area was similar to populations outside the protected area in 17 of 20 comparisons across four measures (data reported as diversity indices). The number of individuals of different size classes was similar in the protected area and exploited populations (>50% of population 0–4 kg in both), but different in the protected area compared to unexploited populations (>50% of population 4–8 kg or more in unexploited populations). In 2007, the protected area was searched by 5–7 people for a total of 10 days, and tortoises weighed, and a blood sample was taken. Genetic and size class data were compared with data from 12 other previously sampled populations, some that were exploited and some that were unexploited (numbers not provided).

    Study and other actions tested
  5. A replicated study in 2009 in eight rock and shrub sites in a desert mountain preserve, Arizona, USA (Sullivan & Williams 2010) found that a protected area surrounded by urban development contained signs of common chuckwalla Sauromalus ater. Common chuckwalla droppings were present in eight rock and shrub sites in a protected area (4–42 droppings/site). The authors report that dropping counts were correlated with plant diversity and the density of six plant species favoured by chuckwallas (see original paper for details). The eight sites in the protected area were rocky outcrops on ridges surrounded by urban development and had been protected for ~50 years prior to urban expansion. In the spring and autumn of 2009, faecal counts (used as an indicator of population size) at basking sites in a 1–2ha area within each reserve were obtained by a single observer over a 1 h period. Belt transects (1x10m) were used to assess crevice numbers, plant diversity and abundance.

    Study and other actions tested
  6. A replicated, site comparison study in 2006–2007 in 15 wetlands in Australian Capital Territory, Australia (Roe et al. 2011) found that waterbodies in nature reserves had lower abundances of eastern long-necked turtles Chelodina longicollis compared to suburban areas and that adult turtles found in nature reserves grew slower and were more likely to be smaller than those in suburban areas. Eastern long-necked turtle abundance was 3 times lower in nature reserve waterbodies (15 turtles/wetland) compared to suburban waterbodies (44 turtles/wetland). Adult growth rates were more than five times lower in nature reserve waterbodies (0.2–0.3 mm/year) than in suburban waterbodies (1.3 mm/year). Smaller adult turtles (120–135 mm long) were found more often in nature reserves, whereas larger adult turtles (135–195 mm long) were found more often in suburban areas (see original paper for details). Turtles were monitored in seven waterbodies in nature reserves and eight in suburban areas within a 55 km2 rural to urban gradient using baited crab traps. Traps were set in September and November 2006 and January and October 2007 (see original paper for details). Turtles were individually marked and measured prior to release.

    Study and other actions tested
  7. A site comparison study in 2006–2007 in semiarid savanna with sparse woody vegetation in the southern Kalahari, South Africa (Wasiolka & Blaum 2011) found that reptile species richness and abundance in protected areas was higher than in nearby unprotected farmland. Reptile species richness and abundance were higher in protected areas (richness: 3 species/transect, abundance: 6 individuals/transect) compared to unprotected farmland (richness: 1 species/transect, abundance: 2 individuals/transect). Ten of 11 reptile species were observed in the protected area compared to eight of 11 in unprotected farmland (see paper for details of individual species abundances). Reptiles were monitored in the Kgalagadi Transfrontier Park (38,000 km2 formed from grasslands protected from 1931–1938) and 11 nearby commercial livestock farms (total unprotected area 10,000 km2) in March–May 2006 and 2007. Reptile abundances and species richness was estimated along 500 x 5m transects (55 transects each in the protected and unprotected study areas) using visual encounter surveys with no movement of logs or leaf litter.

    Study and other actions tested
  8. A replicated, site comparison study in 2002 in four regions of Catalonia, Spain (Garriga et al. 2012) found that the roads in areas with high protection were more likely to have reptile roadkill than in areas with low or no protection. Results were presented as statistical model outputs (see original paper for details). In total, 127 reptiles were collected in spring and 118 reptiles were collected in autumn, the majority of which were Montpellier snakes Malpolon monspessulanus. Roads were surveyed for roadkill in 2002 fortnightly by car in spring (3 times between 14 April and 20 May) and autumn (3 times between 10 October and 15 November) along a randomly selected 20 km stretch of secondary road in each of 41 counties (246 surveys over 4,900 km). The protection status of the area around the road was categorised as high (Natural Park or National Park: 5 roads), low (areas of natural interest: 7 roads) or not protected (29 roads).

    Study and other actions tested
  9. A replicated, site comparison study in 2007–2008 in two areas of mallee woodland in South Australia, Australia (Williams et al. 2012) found that reptile species richness and abundance was higher in conservation parks than in adjacent farmland. Reptile species richness and abundance were both higher within conservation parks (7 species/site; 18 individuals/site) than in adjacent farmland (4 species/site; 11 individuals/site), and on farmland, both richness and abundance declined with increasing distance from the conservation parks (results reported as statistical model outputs, see original paper for details and individual species abundances). In total, 431 reptiles of 31 species were counted. Reptiles were surveyed in mallee woodland (Melaleuca uncinata and Eucalyptus spp.) in two areas in the Eyre Peninsula in December 2007 and January–February 2008. Three replicated sampling blocks were surveyed/area and each block contained two sampling sites within the conservation park (50–750 m from the park boundary) and three sites in adjacent farmland (in remnant habitat in sand dunes or roadside verges, 7–12 km from the park boundary). Reptiles were sampled using 10 pitfall traps and drift fences spaced 25 m apart along a 225 m linear transect in each sampling site. Traps were open for six consecutive 24 hour periods/month.

    Study and other actions tested
  10. A site comparison study in 2009 on a flood plain with lakes and channels in Pará, Brazil (Miorando et al. 2013) found that areas with community-based management (CBM) of fishing practices, that included protecting turtle nesting beaches, limiting use of gill-nets, seasonal fishing restrictions, and a ban on turtle trading had more river turtles (Podocnemis sextuberculata, Podocnemis unifilis and Podocnemis expansa) than areas without CBM. The effect of different aspects of the management programme cannot be separated. Turtles were more abundant in areas with CBM (321 individuals) than in areas without CBM (33 individuals). For Podocnemis sextuberculata, abundance was higher in areas with CBM (14 individuals/1,000 m2 netting/12 hours) than in areas without (2 individuals/1,000 m2 netting/12 hours). Turtle biomass was also greater with CBM (20 kg/1,000 m2 netting/12 hours) than without CBM (3 kg/1,000 m2 netting/12 hours). The fishing agreement that formed the CBM programme had been in place for 20–30 years to protect nesting beaches and reduce illegal trade; though consumption of turtles was still permitted. While 13 communities in the area were a part of the fishing agreement, only two implemented the agreement. Turtle numbers were sampled at 14 sites (7 with CBM; 7 without CBM) in August–October 2009 using gill nets (15 nets/site; 215 m2 nets; 3 each of 5 mesh sizes) with help from local fishers.

    Study and other actions tested
  11. A site comparison study in 2009–2011 in freshwater lakes, rivers and streams in Hong Kong (Sung et al. 2013) found that big-headed turtles Platysternon megacephalum were larger in a stream inside a fenced, patrolled, protected area without turtle harvesting compared to turtles in four national park sites where illegal harvesting is believed to take place. Male and female big-headed turtles captured in the unharvested stream were larger (male: 123 mm long, female: 105 mm long) than male and female turtles in harvested streams (male: 91–104, female: 92–97). Male turtles in the unharvested site were significantly larger than females at the same site, whereas male turtles in harvested sites were of similar size to females in unharvested and harvested sites. In the unharvested site, male turtle density was higher (unharvested: 46 individuals/km; harvested: 3–35 turtles/km), female turtle density was similar (unharvested: 34; harvested: 3–35) and juvenile density was lower (unharvested: 38; harvested: 55–128) compared to harvested streams (results were not statistically tested). Turtles were surveyed in one unharvested stream in a fenced, patrolled conservation area and four streams in national parks where illegal harvesting was believed to take place. Between September 2009 and June 2011, visual encounter surveys (51 total surveys totalling 263 hours) and baited hoop trapping (10–20 traps/site, 5,124 total trapping hours) were carried out.

    Study and other actions tested
  12. A replicated, randomized, site comparison study in 2011 in desert shrub and grassland in the western Mojave Desert, California, USA (Berry et al. 2014) found that in an area with the most human restrictions Agassiz’s desert tortoises Gopherus agassizii were more abundant and had a lower mortality rate. Desert tortoise densities were approximately six-times higher in the most protected area, the Tortoise Natural Area (15 tortoises/km2) than in designated tortoise critical habitat (2 tortoises/km2) and four-times higher than on private lands (4 tortoises/km2). Tortoise annual death rates over the preceding four years were estimated as lowest in the Tortoise Natural Area (3% mortality/year) compared to private lands (6%) and in critical habitat (20%, results were not statistically tested). Tortoises were surveyed in 240 1 ha plots across three different management areas (80 plots/area): Tortoise Natural Area (1973: closed to recreational vehicles; 1980: fully enclosed and closed to mining and livestock grazing, 2010: 12 km of fencing extended to prevent tortoises leaving), critical habitat areas (1994: recreational vehicle use restricted but not enforced with some annual closures, 1990: closed to sheep grazing) and private lands (unregulated sheep grazing, intensive recreational vehicle use, hunting and rubbish dumping). In April–May 2011 plots were surveyed on foot twice/day for live or dead tortoises and field signs.

    Study and other actions tested
  13. A replicated, site comparison study in 2011–2012 in five sites of dry forest, brush and grassland or agricultural lands in La Pampa, Catamarca and Santiago del Estero, Argentina (Sanchez  et al. 2014) found that Argentine tortoises Chelonoidis chilensis were present in one of two protected areas and two of three unprotected sites surveyed. Fourteen tortoises were present in one protected area and none in the second protected area. Three tortoises were counted in two unprotected sites surveyed (1 or 2 tortoises/site) and none in a third unprotected site. In November 2011–March 2012, Argentine tortoises were surveyed in two protected areas and three unprotected sites. Visual encounter surveys were carried out on foot using line transects (100 m long, 30 m wide) and covered 171,000 m2 in each area or site (8–15 hours survey time/site).

    Study and other actions tested
  14. A study in 2007 along a river on the borders of Zambia and Zimbabwe (Nyirenda 2015) found that abundance of Nile crocodiles Crocodylus niloticus was highest in river areas on the edge of national parks. Abundance of Nile crocodiles was higher in river reaches on the edge of national parks (21 crocodiles/km river) compared to areas with less protection (7 crocodiles/km river). In October 2007, Nile crocodiles were surveyed at night by boat using spotlights along a 262 km stretch of the Zambezi river. Two boats with three people (a navigator, recorder and observer) each surveyed a stretch at a time. The river edge bordered national parks (with 75 km2/scout protection levels, use limited to ecotourism and mineral extraction), and other areas with less protection, including game management areas (with 122–123 km2/scout protection levels and multiple legal natural resource uses) and open areas (>200 km2/scout protection and uncontrolled natural resource use).

    Study and other actions tested
  15. A replicated study in 2011–2013 in 22 sites of wetland, cropland, open scrub and forest in Punjab, Pakistan (Rais et al. 2015) found that protected sites overall tended to have higher numbers of reptiles and amphibians combined than unprotected sites, but that protected wetlands tended to have lower diversity of reptile and amphibian species combined compared to unprotected wetlands. Results were not statistically tested. Of 33 species that were observed overall, 19 were present in protected wetlands (total of 2,486 individuals), whereas 27 were present in unprotected wetlands (1,766 individuals). Nineteen species (6,586 individuals) were present in protected areas of mixed open habitat, whereas 15–21 species (154–2,092 individuals) were present in unprotected forest and croplands. Reptiles and amphibians were surveyed using visual encounter methods in 22 sites designated as: protected wetlands, unprotected wetlands, mixed open scrub and cultivated farmland protected as wildlife sanctuaries, and unprotected cropland and tropical thorny forest (number of sites/designation not provided). Surveys were carried out in each site in March–April, July–August, September–October and November–February from March 2011 to July 2013 (6 survey hours/day for 1–3 days at a time).

    Study and other actions tested
  16. A site comparison study in 2012–2015 in semi-deciduous tropical forest and cultivated land in Nayarit, Mexico (Luja et al. 2017) found that inside a protected area the numbers of lizards counted was higher, but snakes and turtles lower than outside the protected area, and the number of species found was similar for lizards and turtles, but lower inside the protected area for snakes. Results were not statistically tested. Eleven lizard species were found both inside and outside of the protected area, and more individual lizards were counted inside (937 individuals) than outside (834 individuals) the protected area. Less snake species and less individual snakes were counted inside the protected area (species: 14; individuals: 30) compared to outside of it (species: 20; individuals: 64). Two turtle species were found both inside and outside of the protected area, but less individual turtles were counted inside (4 individuals) than outside (8 individuals) of the protected area. Reptiles were surveyed inside and outside of a natural protected area using visual encounter surveys on 39 occasions in June 2012–August 2015 (760 survey hours both inside and outside the park).

    Study and other actions tested
  17. A before-and-after study in 2007–2015 in urban parkland with remnant forest in Pará state, Brazil (Avila-Pires et al. 2018) found that most lizard species and one of two amphisbaenian species recorded were still present 20 years after a park was protected. Twenty-two of 25 lizard species and one of two amphisbaenian species found in the park before 1985 were still present after 1990. Two lizard and two amphisbaenian species were recorded in the park after 1990 but not before 1985. A state park was protected from unsustainable resource use in 1993. The park (1,393 ha) included two lakes and remnant woodland and was an important recreational area for neighbouring urban areas. Reptiles were surveyed between March 2007 and January 2009 (81 total days of collecting and 48 days of pitfall trapping) and June 2014 and March 2015 (39 total days of collecting and pitfall trapping combined). Results were combined with herpetological collection records and historical survey data from 1990 onwards and compared with historical records and surveys undertaken before 1985.

    Study and other actions tested
Please cite as:

Sainsbury K.A., Morgan W.H., Watson M., Rotem G., Bouskila A., Smith R.K. & Sutherland W.J. (2021) Reptile Conservation: Global Evidence for the Effects of Interventions for reptiles. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

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