Environmental Statement volume 4 - Chiltern Evergreen3

F4-2.4.5Egg searchThe leaves of submerged vegetation were carefully searched for presence ofgreat crested newt eggs. Once presence of great crested newts was confirmedfor a particular waterbody eg from the torch or bottle trapping, this surveywas no longer necessary.F4-2.4.6TimingAll surveys were carried out during the optimum great crested newt adultbreeding, emergence and migration period, April to June inclusive, with atleast two visits undertaken between mid-April to mid-May.F4-2.4.7Weather ConditionsThe surveys were carried out when the temperature was consistently abovefive degrees Celsius and the torch searches were conducted when the nighttime weather was suitable, ie little or no rain.F4-2.4.8PersonnelAll surveys were carried by two teams, the first led by Beth Seldon of ERM(licence numbers 20081213 and 20091195) and the second by KeystoneEnvironmental staff led by Mark Satinet (licence number 20083106).F4-2.5F4-2.5.1ASSESSMENT METHODOLGYHabitat Suitability Index Assessment (HSIA)The final HSIA score gained for each pond can be used to predict thesuitability of the habitat to support great crested newt. The Great CrestedNewt Habitat Suitability Index Guidelines ( 1 ) indicate that a HSIA score of lessthan 0.5 indicates a pond of poor suitability for great crested newt, a score ofbetween 0.5 and 0.59 indicated a pond of below average suitability, a score ofbetween 0.6 and 0.69 indicated a pond of average suitability, a score of 0.7 to0.79 indicates a pond of good suitability and a score of above 0.8 indicates apond of excellent suitability. The final HSIA score, however, should not beused to prove that great crested newts are absent from ponds.F4-2.5.2Great Crested Newt Population Size Class Assessment – Estimate from FourSurveysFrom the results of the four Presence/Absence surveys, an estimate was madeof population size which is purely for information at this stage. Themaximum adult catches per pond per night for either torch survey or bottletrapping (whichever achieved the highest count) was used to categorise the(1) Amphibian and Reptile Group UK (Regional advice), 2008.ENVIRONMENTAL RESOURCES MANAGEMENTF4-6CHILTERN RAILWAYS