Action: Create artificial hibernacula or aestivation sites
- One replicated, before-and-after study in the UK found that providing artificial hibernacula, along with other terrestrial habitat management, maintained populations of great crested newts.
- One replicated study in the UK found that created hibernacula were used by common frog and smooth newts, but not great crested newts. One replicated study in the UK found four amphibian species close to hibernacula at two of three sites.
Amphibians need damp sheltered places for overwintering or aestivating during hot arid summers. Overwintering or aestivating sites, or ‘hibernacula’, can be created for amphibians where natural sites are limited or where these habitats have been lost, for example at newly restored sites or in gardens.
Supporting evidence from individual studies
A replicated, before-and-after study in 2005 of four mitigation projects in England, UK (Lewis, Griffiths & Barrios 2007) found that providing artificial hibernacula and refugia for great crested newts Triturus cristatus helped to maintain populations (see also Lewis 2012). Populations persisted at all four sites following development, although numbers were lower than pre-development at two sites. After three or more years, three of the populations were classified as ‘medium’ sized (peak count: 19–86) and the other as ‘large’ (167). Mitigation projects during development work had been carried out at least three years previously. Artificial hibernacula and refugia were created at sites in 1992–1999. Terrestrial habitat management was also undertaken at the sites and two sites received 37–73 translocated newts. Monitoring was undertaken in March–May 2005 using egg searches, torch surveys, bottle trapping and mark-recapture.
A replicated study in 2004–2005 of three created hibernacula in parkland in Lancashire, UK (Neave & Moffat 2007) found that they were used by common frogs Rana temporaria and smooth newts Triturus vulgaris. Thirty-one frogs and nine smooth newts were captured leaving the hibernacula. Although great crested newt Triturus cristatus were recorded breeding in the adjacent pond, none were found to use the three hibernacula. Six hibernacula were created around a pond in 2002. Drift-fencing with four pitfalls were installed around three of the hibernacula in December 2004. Traps were checked in January–March 2005.
A replicated study in 2007–2008 of 10 created hibernacula at three sites in Tyne and Wear, UK (Latham & Knowles 2008) found four amphibian species near hibernacula at two of the sites. In autumn six common frogs Rana temporaria and nine common toads Bufo bufo were found under tiles at two of the sites (with six hibernacula). In spring six great crested newts Triturus cristatus, six smooth newts Triturus vulgaris, seven common toads and two common frogs were caught in pitfall traps near the two hibernacula at one of those sites. Hibernacula were constructed in 2005–2007 by excavating an area 2 x 1 m and 0.5 m deep. This was filled with rubble and covered with tree cuttings and leaves, a permeable geotextile fabric and then soil and grass turf (total height 1 m). In autumn, amphibians were surveyed using six roofing felt tiles (0.5 x 0.5 m) around each hibernaculum. At one site a combination of drift-fencing and pitfall trapping was used to monitor species in spring.
A continuation of a study (Lewis, Griffiths & Barrios 2007) in 2005–2010 of four mitigation projects in England, UK (Lewis 2012) found that providing artificial hibernacula and refugia, along with other management for great crested newts Triturus cristatus helped to maintain populations. Numbers initially decreased at two sites (2005: over 100 to 19; 42 to 31), but increased to 60 newts at both sites by 2009 and 2010 respectively. Populations decreased from 2005 to 2010 at the other two sites (167 to 10; 86 to 40). Artificial hibernacula and refugia were created at sites in 1992–1999. Terrestrial habitat management was also undertaken at the sites and one site received 73 translocated newts. Monitoring was undertaken in March–May using egg searches, torch surveys, bottle trapping and mark-recapture.
- Lewis B., Griffiths R.A. & Barrios Y. (2007) Field assessment of great crested newt Triturus cristatus mitigation projects in England. Natural England report. Natural England Research Report NERR001.
- Neave D.W. & Moffat C. (2007) Evidence of amphibian occupation of artificial hibernacula. Herpetological Bulletin, 99, 20-22
- Latham D. & Knowles M. (2008) Assessing the use of artificial hibernacula by great crested newts Triturus cristatus and other amphibians for habitat enhancement, Northumberland, England. Conservation Evidence, 5, 74-79
- Lewis B. (2012) An evaluation of mitigation actions for great crested newts at development sites. PhD thesis. The Durrell Institute of Conservation and Ecology, University of Kent.