Appendix 10F Appendix 10F - Ecology and Nature Conservation A 10F 1
1 Introduction 1.1 Background 1.1.1 This appendix details the findings of studies and surveys that have been undertaken to determine the potential presence of great crested newts (GCN) in the vicinity of the proposed Croxley Rail Link. 1.2 Scope of the Studies and Surveys 1.2.1 The following studies and surveys have been undertaken: A desk-based review of existing records relative to the species within a 1km study area centred on the proposed link; a review of existing OS mapping to establish the presence of waterbodies with the potential to support the species; Habitat Suitability Index (HSI) surveys to determine the potential of identified waterbodies relative to the species; and presence or likely absence surveys for waterbodies where the HSI surveys confirmed potential. 1.3 Statutory Context 1.3.1 GCN are fully protected through their inclusion within the Conservation of Habitats and Species Regulations 2010 as a European Protected Species (EPS). Under the legislation, it is an offence to deliberately capture, injure or kill a great crested newt or deliberately take or destroy the eggs of a great crested newt. It is also an offence to damage or destroy a breeding site or resting place of a great crested newt. The great crested newt is also protected from deliberate disturbance. 1.3.2 GCN also receive some protection through inclusion in Schedule 5 of the Wildlife and Countryside Act 1981 (as amended). This legislation protects a great crested newt from intentional or reckless disturbance when using places or structures that are used for protection or shelter and also protects the animals from being obstructed from entering such places. 1.4 Conservation Status 1.4.1 GCN are listed as a UK and Hertfordshire Biodiversity Action Plan (BAP) priority species. 1.4.2 By virtue of Section 74 CROW Act 2000 and Section 40 NERC Act 2006, all public authorities are obliged to take steps to further the conservation status of species of conservation concern in England. These species of conservation concern are taken as priority BAP species (section 74(4) CROW Act 2000). Appendix 10F - Ecology and Nature Conservation A 10F 2
2 Data Sources and Survey Methods 2.1 Data Sources 2.1.1 The following data sources and organisations were referenced and contacted to establish current records relating to the presence of the species as part of the 1km desk-based review: Hertfordshire Biological Records Centre (HBRC); London, Essex and Hertfordshire Amphibians and Reptiles Trust (LEHART); and National Biodiversity Network (NBN) website - http://www.nbn.org.uk 2.2 Identification of Waterbodies 2.2.1 GCN inhabit both aquatic and terrestrial habitats. They breed in water and their range is within 500m of the breeding waterbody (English Nature, 2001). However, 250m is the distance over which they are most active and forms the majority of their terrestrial habitat (Baker J.M.R., 1999). Therefore, all waterbodies within 250m of the proposed scheme were identified from 1:25000 Ordnance Survey maps and aerial photography, as well as those incidentally identified during other surveys. Waterbodies that have an obvious flow are not considered suitable habitat for great crested newts (Oldham et al., 2000). 2.3 Habitat Suitability Index (HSI) Survey 2.3.1 All ponds identified during the desk-based study were assessed for their suitability to support great crested newts on the 4 August 2009. The standard Habitat Suitability Index (HSI) devised by Oldham et al. (2000) following the HSI guidance issued by the National Amphibian and Reptile Recording Scheme (NARRS, 2007) was used. The HSI for great crested newts incorporates ten suitability indices (SI) which are factors that affect the species. The HSI is a numerical index, between 0 and 1, with the scores categorized as follows: <0.5 Poor suitability for great crested newts; 0.5 0.59 Below average; 0.6 0.69 Average; 0.7 0.79 Good; and > 0.8 Excellent. 2.3.2 Natural England recommends a threshold HSI score of 0.5 as an indication that a pond is of very low value to great crested newts and is unlikely to support them. Presence / likely absence surveys were accordingly only undertaken at waterbodies scoring greater than 0.5. 2.3.3 HSI assessment is only suitable for use on ponds. Streams with no visible flow or ditches with standing water were subject to professional judgement on their suitability to support great crested newts. Appendix 10F - Ecology and Nature Conservation A 10F 3
2.4 Presence or Likely Absence Survey 2.4.1 GCN presence or likely absence surveys were undertaken in accordance with the Herpetofauna Worker s Manual (Gent & Gibson, 1998), with a range of survey methods employed by licensed ecologists during suitable weather conditions. To determine presence or likely absence, at least three methods were employed per visit on at least four different occasions (suitable weather conditions between mid-march and mid-june), with at least two surveys at each waterbody completed between mid April and mid May. The surveys were undertaken on the 8, 15, 26 and 27 April 2010. The following survey methods were employed at suitable ponds: egg searching, torch surveys and bottle-trapping. Appendix 10F - Ecology and Nature Conservation A 10F 4
3 Findings 3.1 Desk Study 3.1.1 The desk based review established that the data sources and consultees hold no current evidence of the species within the 1km study area. 3.1.2 The review of the OS mapping did, however identify two waterbodies within the 250m site survey area which warranted further investigation. The two waterbodies comprise a section of stream which crosses the alignment of the proposed link in the vicinity of Ascot Road and a pond located south of the proposed alignment within the Holywell Allotments. 3.1.3 The stream comprises a short section of watercourse with no visible flow, which is isolated by the A412 to the north, Ascot Road to the east, the River Gade to the west and an industrial estate to the south. It has become overgrown and choked with vegetation and is heavily shaded by enclosing wet woodland. Water quality appeared poor. There was also substantial pollution in the form of litter along and within the watercourse. Part of the drain runs underneath the A412. Taking these factors into account, it was concluded that the stream is unlikely to support great crested newts. 3.1.4 The pond located within the Holywell Allotments is surrounded by terrestrial habitat which appeared particularly suitable for great crested newts, however the pond is isolated and the only other pond on the allotment had dried out. 3.1.5 The results of the HSI surveys for the stream and pond are scheduled in Table 10F-1. Table 10F-1: HIS Data Waterbody Stream 1 Pond 2 Parameter Score SI Score Score SI Score 1. Pond Location A n/a A 1 2. Pond area (m3) 100 n/a 120 0.2 3. Pond drying (years) Rarely n/a Rarely 1 4. Water quality Poor n/a Good 1 5. Shade (%) 95 n/a 0 1 6. Waterfowl Absent n/a Absent 1 Appendix 10F - Ecology and Nature Conservation A 10F 5
7. Fish Possible n/a Possible 0.67 8. Pond count None n/a None 0.1 9. Terrestrial habitat Moderate n/a Good 1 10. Macrophytes (%) 30 n/a 60 0.9 HSI Score n/a as it is a stream 0.64 Presence or Likely Absence Surveys 3.1.6 No evidence of great crested newts, including adults, larvae or eggs, was recorded in the pond during the four survey visits. 3.1.7 The surveys did, however, establish the presence of a breeding population of smooth newts Triturus vulgaris. The results are summarised in Table 10F-2. Table 10F-2: Summary of Presence or Likely Absence Surveys in Pond Date Amphibian Presence / Absence Species Recorded Number GCN Eggs GCN Larvae Smooth Newt Eggs 08/04/10 Smooth newt 16 No No Yes Triturus 15/04/10 vulgaris 1 No No Yes 26/04/10 3 No No Yes 27/04/10 7 No No No Appendix 10F - Ecology and Nature Conservation A 10F 6
References Baker J.M.R. (1999). Abundance and Survival of Great Crested Newts (Triturus cristatus) at a Pond in Central England: Monitoring Individuals. Herpetological Journal 9; 1-8. English Nature (2001). Great Crested Newt Mitigation Guidelines. English Nature. Froglife (2003). Surveying for (Great Crested) Newt Conservation. Froglife Advice Sheet 11. Froglife. Gent, T. & S. Gibson (2003). Herpetofauna Workers Manual. Joint Nature Conservancy Council. Government Office for the East of England. (2008). East of England Plan. The Stationary Office. IEEM, (2006). Guidelines for Ecological Impact Assessment, Institute of Ecology and Environmental Management, http://www.ieem.org.uk/ecia/index.html. Joint Nature Conservation Committee (JNCC). (2003). Great Crested Newt Species Action Plan. JNCC. Langton, T.E.S., C.L. Beckett, & J.P. Foster (2001). Great Crested Newt Conservation Handbook. Froglife. Oldham R., J. Keeble, M. Swan & M. Jeffcote (2000). Evaluating the Suitability of Habitat for the Great Crested Newt (Triturus cristatus). Herpetological Journal 10:143-156. Appendix 10F - Ecology and Nature Conservation A 10F 7