Create artificial refuges, hibernacula and aestivation sites
Overall effectiveness category Awaiting assessment
Number of studies: 11
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Background information and definitions
Reptiles need shelter for overwintering or aestivating during hot arid summers. Artificial overwintering or aestivating sites, or ‘hibernacula’, can be created for reptiles where natural sites are limited or where these habitats have been lost, for example at newly restored sites or in gardens.
Other studies investigating the creation of shelter habitat are discussed in Add woody debris to landscapes; Create artificial burrows; Create or restore rock outcrops; Threat: Biological resource use – Leave woody debris in forests after logging and Leave standing/deadwood snags in forests.
Supporting evidence from individual studies
A replicated, controlled study in 1977–1979 in three riverine forest sites in Louisiana and Mississippi, USA (McComb & Noble 1981) found that artificial nest boxes were used by six reptile species. In total six reptile species were found in nest boxes and occurred in 0.3–11.3% of large boxes, 0.4–5.9% of medium boxes and 1.3–5.4% of small boxes compared to 1.2–2.0% of natural tree cavities (reptile numbers and species not provided). Boxes were erected in hardwood and hardwood/pine forests and were of three sizes: large (60 x 30 x 30 cm, 13 cm diameter entrance), medium (45 x 20 x 20 cm, 7.5 cm diameter entrance) and small (30 x 15 x 15 cm, 5 x 7 rectangle entrance). Fifty boxes were installed at two sites and 90 at the other. All boxes had 5–10 cm of pine shavings in the bottom. Boxes and natural cavities were inspected every month from April 1977 to February 1979.Study and other actions tested
A study in 1999 on a heathland site in Berkshire, southern England, UK (Stebbings 2000) found that an artificial hibernaculum was used by common lizards Zootoca vivipara and adders Vipera berus. Following construction, three adult lizards were observed basking near entrance holes and three adder skins were discovered. An artificial hibernaculum was constructed 40 m away from a bank that was to be destroyed as part of a road development. A ditch was dug (20 x 1 x 1 m) and hollow concrete building blocks were used to create underground chambers, with plastic piping (5 cm diameter) providing entrance tunnels. Bark mulch was added to any gaps and the structure was backfilled and covered with turf and native shrubs. Observations of reptiles at the hibernaculum were conducted on one day in April 1999.Study and other actions tested
A replicated, site comparison study in 2000–2001 in a site of grassland with wooded patches in Victoria, Australia (Michael et al. 2004) found that more reptiles tended to use old log refuges compared with new log refuges. Three species were found more commonly under old logs compared to new logs (tessellated gecko Diplodactylus tessellatus: 6 individuals in old logs vs 2 in new logs, Boulenger’s skink Morethia boulengeri: 12 vs 6; curl snake Suta suta: 38 vs 7). Three species were found in similar numbers under old and new logs (striped legless lizard Delma impar: 1 in old logs vs 2 in new; olive legless lizard Delma inornate: 6 vs 9; Grey’s skink Menetia greyii: 23 vs 9) and two species were found under only one log type (bearded dragon Pogona barbata: 1 under new log; eastern brown snake Pseudonaja textilis: 2 under old log). An area of 3,780 ha was marked into 91 quadrats and in May 2000, and 12–20 logs (old fence posts) were placed in every quadrat (total of 1,131 log refuges). An additional 271 fallen fence posts that had lain in situ for 15 years were also monitored. Monthly surveys took place between June 2000 and January 2001.Study and other actions tested
A study in 2004–2005 in scrub and grassland in Suffolk, UK (Showler et al. 2005) found that artificial hibernacula were used by translocated common lizards Lacerta zootoca vivipara. Six months after lizards were first translocated to the hibernacula, both adult and juvenile lizards were observed basking around each hibernaculum. Three hibernacula were constructed (east-west ditches 20 m long, 1 m deep and 1.5 m wide with approximately 70° sloping edges) and filled with a mixture of drainage pipes, bricks, gravel, rubble, vegetation cuttings, logs and soil in autumn 2004. Plastic piping was added to facilitate lizards entering and entrances restricted in size to limit access by predators such as weasels Mustela nivalis and brown rats Rattus norvegicus (see original paper for details). Approximately 70 lizards were caught and translocated in autumn 2004 and spring 2005. Lizard use of the hibernacula was monitored from March 2005.Study and other actions tested
A replicated study in 2003–2004 in two grazed farmland sites near Canterbury, New Zealand (Lettink & Cree 2007) found that artificial refuge design was important for common geckos Hoplodactylus maculatus but not McCann’s skinks Oligosoma maccanni or common skinks Oligosoma nigriplantare polychroma. Common geckos preferred artificial refuges made from Onduline (a corrugated roofing product made of organic fibers: 602 total captures) compared to corrugated iron (109 total captures) or concrete roofing tiles (27 total captures). Similar numbers of McCann’s skinks and common skinks were captured under each artificial refuge material (McCann’s Onduline: 28 total captures vs. iron: 22 vs. concrete: 36; common skink 21 vs. 23 vs. 30). The refuges were triple-layered and common geckos were captured 344 times in the top spaces, 316 times in the middle spaces and 51 times in the bottom spaces. At each site, a 5 x 6 grid of ‘refuge stations’ spaced 5 m apart was installed. Each station consisted of three triple-layered artificial refuges made of different materials: Onduline, iron and concrete roofing tiles. All refuges were checked monthly from December 2003 until November 2004.Study and other actions tested
A replicated study in 2004–2005 in fenced sand and grass enclosures in South Australia, Australia (Mensforth & Bull 2008) found that gidgee skinks Egernia stokesii zellingi preferred artificial refuge structures with more crevices than those with fewer. Skinks spent more time on artificial refuge structures with more crevices (41 minutes/skink) than on those with fewer crevices (16 minutes/skink). Skinks spent more time taking refuge in the crevices of artificial refuges with more crevices (25 minutes/skink) than in those with fewer crevices (5 minutes/skink). Artificial refugia were created from 3 cm thick concrete slabs (40 x 40 cm or 60 x 60 cm) and placed in four outside pens (3 x 1.4 m) with a sand and grass substrate. For each trial, two refugia were provided at each end of the pen (60 cm apart). Each refuge had a base (1.2 x 1.2 m) made of four slabs. One, four or eight crevices were added to each structure using timber or slabs (see original paper for details). Skinks used in the trials were from a captive colony. Skinks were individually marked with paint prior to being placed in a pen (1 or 4 individuals at a time) and left undisturbed for 20 minutes. Skink behaviour was monitored by video camera for the following 60 minutes. Thirty trials were carried out in September 2004–March 2005.Study and other actions tested
A controlled, before-and-after study in 2000–2006 of a riparian site of Mediterranean shrubs in southwestern Spain (Márquez‐Ferrando et al. 2009) found that restoration sites with refuge logs had higher abundance and species richness of reptiles than sites without logs. After 2–4 years, the site with refuges hosted more reptiles than the site with no refuges (refuges: 4–7 individuals/hour; no refuges: 1–3 individuals/hour) and the number of species seen/hour was also higher (refuges: 1.4–1.7 species/hour; no refuges: 0.8–1.3 species/hour). Overall species richness after 2–4 years was similar for the site with refuges (6 species) and a nearby intact site (7 species), and lower for the site with no refuges (5 species) compared to the intact site. Large scale restoration of a riparian corridor (4,200 ha) began following a mining accident in 1998. In 2002, one 24 ha site was provided with 120 reptile refuges: two logs (1.2 m long) placed side by, distributed evenly across the site. Another site (24 ha) received no logs. An additional site outside the affected corridor was also sampled. Reptile surveys began in 2000, and in 2002–2006, at least three surveys were carried out each year, each lasting 4–5 hours.Study and other actions tested
A randomized, controlled, before-and-after study in 2004–2006 on a coastal duneland site on South Island, New Zealand (Lettink et al. 2010) found that providing artificial refuges for McCann’s skink Oligosoma maccanni did not lead to an increase in survival compared to when no refuges were provided. Average change in skink survival before and after refuges were provided did not differ from zero. Change in survival was also no different from zero when artificial refuges and exclosure fencing were provided together. Four sites each were assigned to one of four treatments: artificial refuges (32 refuges/site, 16 each of two designs); artificial refuges and exclosure fences (25 x 25 m area, 1 m high chicken wire fence, bird netting on top); exclosure fences only; and no treatment. Refuges were made of corrugated roofing and cladding. Skinks were sampled annually using a 4-day pitfall trapping session in February and March 2004–2006 with fencing and refuges placed into randomly allocated sites immediately before the second year.Study and other actions tested
A study in 2009–2011 in grazed marsh in Norfolk, UK (Whiting & Booth 2012) found that some translocated adders Vipera berus released onto man-made hibernacula bred, returned to the hibernacula to overwinter and survived for at least 18 months. Six months after translocation, up to 22 adders/day were recorded on the man-made hibernacula, including one newborn adder, indicating breeding success. Eighteen months after translocation, 21 of 119 translocated adders were sighted on or near the hibernacula. In addition, 19 new adders were observed in the vicinity. Viviparous lizards (including juveniles) and grass snakes Natrix helvetica were also recorded on and near the hibernacula 12–18 months after they were built. In September 2009, three hibernacula (100 m approximate length; 1.5 m high, 3 m wide with 45° front and rear slopes) were constructed from natural materials on grazing marshes separated by drainage ditches. Each hibernacula and some adjacent grazed land (1 ha total) were enclosed by semi-permanent fencing (plastic sheeting and wooden posts). In March 2010, a total of 119 adders were translocated from nearby flood banks that were subject to flood defence works (which took place May-October 2010). The fencing was opened from mid-May 2010. Adders were monitored in September–October 2010, March–May and July–September 2011.Study and other actions tested
A replicated study in 2013–2015 in an area of Mediterranean shrubland in Savona Province, Italy (Ghiglione et al. 2016) found that one of six artificial shelters consisting of a concrete block was used by a female ocellated lizard Timon Lepidus to lay a clutch of eggs. Two years after six artificial shelters were installed, a single female lizard laid a clutch of nine eggs in one of the shelters. Two months later the shelter was found to have been destroyed and the fate of the eggs was unknown. In 2013, six artificial shelters were installed that consisted of a hollow concrete brick (12 x 7 cm opening and 40 cm deep) camouflaged by stones and branches. Shelters were monitored in March–October: seven times in 2013, once in 2014 and twice in 2015.Study and other actions tested
A randomized, controlled study (years not provided) of artificial refugia in Australia (Bourke et al. 2017) found that Boulenger’s skinks Morethia boulengeri preferred timber refuge material compared to cement tiles or corrugated iron, but that this preference was affected by the size of the gap between the refuge and the ground. Skinks selected timber refuges over corrugated iron refuges (timber: 21 skinks; iron: 6 skinks) and timber over cement tiles (timber: 19 skinks; cement: 9 skinks), but showed no preference for corrugated iron or cement tiles (iron: 14 skinks; cement: 14 skinks). When the preferred timber refuges were raised from 1 cm to 2.5 cm above ground, all skinks (10 of 10) preferred corrugated iron with gaps of 2 cm, but preference for standard timber (2.5 cm gaps) and flattened iron (<=1 cm gaps) was equal (5 skinks selected each). Twenty-eight skinks collected from two different areas were presented with choices between two different refuge materials (either timber, corrugated iron or cement tile). Twenty of those skinks were then given the choice of a timber refuge or corrugated iron refuge raised to different heights above the ground (timber: height changed from 1 cm to 2.5 cm above ground; corrugated iron was flattened from 2 cm gaps to <=1 cm). Experiments were carried out in laboratory conditions.Study and other actions tested
Where has this evidence come from?
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This Action forms part of the Action Synopsis:Reptile Conservation
Reptile Conservation - Published 2021