Recent concerns over declining amphibian populations have prompted renewed international efforts to determine the status and diversity of amphibian assemblages (Griffiths & Beebee 1992).  Comparisons between different studies and different works can only be made if standardised guidelines for survey and monitoring are adhered to.  Heyer et al. (1994) provide a comprehensive review of amphibian surveying methods, and present ten standardised sampling procedures.  Unfortunately, their review has a strong North American bias, and provides inadequate coverage of the techniques widely used in Britain and Europe.  Moreover, most of the methods they recommend require execution by a trained biologist.  Stumpel & Siepel (1993) provide a general summary of the monitoring requirements and natural history of reptiles and amphibians in the Netherlands, but do not propose any standardised methods.

In Britain, the methods available for surveying frogs and newts are well-established (e.g. Griffiths 1985; British Herpetological Society 1990; Swan & Oldham 1993).  Cooke (1995) recently compared three methods for surveying for crested newts at a single site in Cambridgeshire.  Overall counts by torch light were positively related to the numbers trapped and netted during the season.  However, Griffiths & Raper (1994) have highlighted the diversity of opinions regarding the effectiveness of the various techniques.  A highly effective method may not necessarily be either the most practical or the most popular.  With field surveys relying heavily on the voluntary sector, any standardisation of survey methods must be a compromise between those techniques which are most effective for a given species and those with which surveyors feel most comfortable.  Rather than recommend that records adhere to using a single method, it is more practical to retain a range of available methods and attempt calibration between them.  Before such a calibration can be made, however, it is important that different methods of data collection are standardised.

This report provides a comparison and calibration of those methods used for surveying common frogs and newts.  The procedure described should allow populations which have been surveyed by different methods to be compared with a degree of confidence.  Using the data gathered from a random sample of ponds, objective criteria have been developed for assessing the status of newt populations for conservation purposes.