Appendix 11T Smooth Newt Lissotriton vulgaris

Transcription

1 Appendix 11T Populations of smooth newt and their habitats are considered potentially significant nature conservation receptors for the Proposed Scheme for the following reasons: The smooth newt and its habitats are fully protected in Northern Ireland under The Wildlife (Northern Ireland) Order 1985 (as amended); and There has been a significant decline in smooth newt habitat across Northern Ireland (O Neill et al., 2004). Legislation The smooth newt is listed within Schedule 5 to The Wildlife (Northern Ireland) Order 1985 (as amended). Therefore the smooth newt receives full protection in NI from the following offences: (i) intentional killing, injuring, taking or possession; (ii) intentional damage, destruction or obstruction of access to any structure or place used for shelter or protection; and, (iii) intentional disturbance while occupying structures or places used for shelter or protection. This legislation applies to all life-stages, including eggs. The smooth newt is also listed on Annex III to the Bern Convention on the Conservation of European Wildlife and Natural Habitats. Mouchel 2010 A.11T-1

2 Conservation Status The smooth newt is widespread throughout NI (O Neill et al., 2004) and is not currently threatened or rare enough to warrant listing as a UK or Northern Irish Species of Conservation Concern (SoCC) or Biodiversity Action Plan (BAP) species. It is also not listed within the Londonderry or Omagh local BAPS. Therefore, the conservation status of the smooth newt in NI is currently considered favourable, although, due to anthropogenic encroachment, habitats used for the purpose of breeding and shelter by the species have undergone a significant decline and the species is likely to become threaten in the near future (O Neill et al., 2004). Mouchel 2010 A.11T-2

3 Policy Framework and Guidance Notes The following policies and guidance documents aim to help conserve and protect the smooth newt within NI and the study area: Planning Policy Statement (PPS) 2 - Planning and Nature Conservation; ENV1.1 in The Regional Development Strategy for Northern Ireland 2025: Shaping Our Future, Chapter 12, Caring for the Environment; Northern Ireland Biodiversity Strategy and associated Plans; and Roads Service Biodiversity Implementation Plan. There are no local planning policies that offer specific protection for the smooth newt. Mouchel 2010 A.11T-3

4 Baseline Data Collection The methods used to collect information regarding smooth newt included: Obtaining up-to-date details of the location and nature of all statutory and non-statutory designated sites, notified for their value to smooth newt, within the study area from (the Northern Ireland Environment Agency (NIEA)); Collation of information from desk-based sources relating to the presence of smooth newt in NI and potential distribution and habitat preference; Completion of detailed field surveys to identify the presence/likely absence of smooth newt within the vicinity of the Preferred Route; and Completion of detailed field surveys to inform the population class size of smooth newts when found to be present. Selection of Field Survey Sites Standing water bodies were identified from desk study data, phase 1 habitat surveys, ordinance survey maps and aerial photography. Flowing water habitats (rivers, streams and drainage ditches with obvious water movement) were not considered. The water bodies were then visited in February 2009 by senior ecologists who completed a screening assessment of each waterbody s suitability to support significant populations of smooth newt. The method for the screening assessment was a system of classification where water bodies were designated as having either high or low potential to support breeding smooth newts. The classification was based on the habitat variables, identified from the literature, that were reported to have the greatest influence on the presence of smooth newts in a pond i.e. those features that are most likely to encourage newt colonisation. Recent (O Neill et al., 2004; Marnell, 1998) and classic (Beebee, 1983) studies identified three habitat variables as exerting the greatest influence on the presence of smooth newts in a pond, including: 1) pond shape (or linearity; effectively if the waterbody in question is pond-like or ditch-like); 2) structure of emergent vegetation (covering all the water body, not present or a mosaic of vegetation and open water); and, 3) type of surrounding habitat (scrub, grassland, bog etc). Beebee (1983) studied water bodies (specifically ponds) in south-eastern England along an agricultural land-heathland transect, and found smooth newts preferentially colonised ponds in agricultural areas and avoided heathland areas due to the acidic character of the landscape and ponds there. Working in NI, Marnell (1998) also found smooth newts avoided acidic habitats including bogs, but determined that the vegetation within and surrounding water bodies played a role in making them suitable; with water bodies of relatively high value possessing emergent vegetation and open water in a mosaic (i.e. rather than the pond being choked with or devoid of vegetation), and surrounding vegetation composed predominantly of scrub or woodland with large amounts of deadwood available as refugia. In a follow-up study using some of the sites included in Marnell (1998), O Neill et al. (2004) confirmed that emergent and surrounding vegetation type was important in determining likely colonisation of water bodies by smooth newts, but also showed that Mouchel 2010 A.11T-4

5 a water body s shape, whether ditch-like or pond-like, was key in NI, with smooth newts selecting against ditch-like waterbodies. Additional variables have been identified by several other studies that either were from other countries in Europe (with markedly different habitats) or have shown weak correlations. Laan (1990) found water body age to be an important factor in determining smooth newt colonisation in the Netherlands, in agreement with Pavignano et al., (1990) who studied water bodies in northern Italy and found that, in addition to age and the factors used in our classification system, the degree of human interference was also important. As age and physical interference are likely to be linked to the cover of emergent vegetation present (i.e. disturbed ponds are likely to lack emergent vegetation, as are young ponds), and we omitted these additional variables. Using this information the defining characters of low and high value water bodies were determined. For each of the three variables a number of possible responses were identified and scored as having either a positive (+) or negative (-) impact on smooth newt colonisation. A high value water body was defined as those scoring three positive responses, with low value water bodies scoring between zero and two positive responses. Table 11T.1 details the scoring of the possible responses. Table11T.1 Classification of Possible Responses for Each Habitat Variable Identified as Influencing Colonisation of Water Bodies by Smooth Newts. 1. Water body shape 2. Structure of emergent vegetation 3. Type of surrounding vegetation Pond (+) Ditch (-) Choked with vegetation (-) No emergent vegetation (-) Vegetation/open water mosaic (+) Bog/mire (-) Open grassland, little dead wood (-) Heathland (-) Scrub (+) Scrub/grassland mosaic (+) Woodland (+) Woodland/grassland mosaic (+) Mouchel 2010 A.11T-5

6 A total of 17 ponds located within 250m of each route option received a high score. All these ponds were selected for smooth newt field census. In addition, all other ponds (those with a low score) were numbered and a total of 14 were selected for field census at random, using the random number generator tool in Microsoft excel. The identity of the ponds, with respect to their score (high or low), was not revealed to the field surveyors until after the all field census was complete. Field Survey The sub-sample of ponds chosen during the selection and classification process detailed above were subjected to surveys to confirm the presence/likely absence of smooth newt and, where appropriate, any relative population size class. All surveys were carried out by experienced and licenced surveyors in accordance with the methodologies provided in Design Manual for Roads and Bridges (DMRB) Volume 10 Section 4 Part 6 HA 98/01 Nature Conservation Management Advice in Relation to Amphibians and by NIEA ( Volume 10, Section 4, Part 6 makes reference to the need to adhere to methods provided by Joint Nature Conservation Committee (JNCC) (Gent and Gibson, 2003). Consequently, the field surveys were all completed in reasonable accordance with the methods for smooth newt census outlined in that document. All surveys were undertaken under suitable climatic conditions (air temperature >5ºC) between mid-march and end-may 2009 (optimal months for the completion of newt surveying). Each survey site visited on at least four separate occasions and if smooth newts were recorded during any of these visits then a further two census visits were completed. Any newts recorded were classified, where possible, as to sex and age class. The field surveys were completed using three main search methods; egg searches, searches by torchlight and dip netting. The use of bottle trapping is not permitted in NI. The methods used are detailed below. Egg Searches The method involved searching both live and dead submerged pond vegetation for newt embryos during daylight hours. The searches were conducted with care not to damage the eggs or the marginal vegetation. Once an egg was found and confirmed as that of a smooth newt, the search for that pond was terminated to ensure that no further disturbance to eggs occurred. It is important to note that numbers of eggs present are not indicative of population sizes. Net searches This method involved using a standard dip net to sample areas around pond margins. In an effort to standardise the surveys, the survey protocol consisted of a perimeter walk around the pond with a survey effort of 15 minutes of netting for every 50 meters of shoreline. All netting bouts were completed during the daylight hours. Due to the intrusive nature of net searches, they were used solely to help determine presence/likely absence and ceased if the presence of smooth newt was confirmed in a pond. Mouchel 2010 A.11T-6

7 Torch Surveys Torch surveys were used to help confirm both presence/ likely absence and to determine relative population class size estimates. Once a positive record of smooth newt in a pond had been made, torch surveys were the sole method used to complete census until all six visits were concluded. All torch surveys were completed at night and several hours after any dip net surveys, so that enough time had elapsed for any disturbed sediments that may have otherwise affected water clarity and limited visibility to have resettled. The torch surveys involved shining a high powered torch (1,000,000 candle power) around the margins of the waterbody and recording any newts observed. The margins of each pond were walked around once and the start time and end time of the survey was recorded to ensure consistency in survey effort and duration. Areas of the pond that were not accessible were identified during the first visit and were excluded from all further survey visits. This survey method was always undertaken when there was little or no wind or rain. Statistical analysis The Mann-Whitney U test was used to assess the differences in smooth newt numbers recorded from the low and high ponds. Mouchel 2010 A.11T-7

8 Limitations The preliminary selection and classification process identified 33 ponds that were to be surveyed. However, two of these ponds did not receive a full survey effort due to the refusal of access from landowners ( high ponds 46 and 47). Pond 77 was not subject to a full survey due to poor time restrictions. Whilst this reduced the number of ponds available census the scope of the surveys across the study area was otherwise comprehensive and sound conclusions can be drawn from the data gathered on the likely value of the smooth newt populations of relvance to the scheme. Mouchel 2010 A.11T-8

9 Designated Sites There are no sites within the study area that are designated specifically for the presence of smooth newt. Mouchel 2010 A.11T-9

10 Existing Species Records Although some records of smooth newt exist for County Londonderry and County Tyrone, none of these records fall within the study area. Mouchel 2010 A.11T-10

11 Field Survey Table 11T.2 provides a summary of the raw field survey dataset that is available on request. It also provides the population class size estimates. It shows that smooth newts were recorded from a total of 18 ponds, including 14 of the 16 high ponds (87%). Smooth newts were found to be absent from a total of 11 ponds, including 9 of the 14 low ponds (64%). Smooth newts were recorded in 6 low ponds; however with exception to pond 10, whenever smooth newts were recorded in low ponds the peak counts never exceeded 8 animals and therefore the ponds supported low sized populations. All ponds that supported good populations were high ponds (100%). In summary, significantly more smooth newts were recorded from high ponds than from low ponds (U = 32; p < 0.05). Figure 11T.1 Comparison of The Number of Smooth Newts Recorded from Low Ponds (Sample 1) and High Ponds (Sample 2) Within the A5WTC Study Area. Significantly More Newts were Recorded from High Ponds (U = 32; N = 15; P < 0.05). 35 No. smooth newts Sample1 Sample2 Pond Category Mouchel 2010 A.11T-11

12 Table 11T.2 (1989) Summary of Survey Results and Population Class Size Estimate, Calculated Using NCC Pond Reference Screening Score Smooth Newt Peak Counts Population Class Size 4 LOW No 0 n/a 10 HIGH Yes 33 Good 14 LOW No 0 n/a 17 HIGH Yes 30 Good 18 HIGH Yes 7 Low 23 LOW No 0 n/a 25 LOW Yes 4 Low 26 LOW No 0 n/a 28 LOW No 0 n/a 31 LOW Yes 1 Low 33 LOW Yes 4 Low 34 HIGH Yes 29 Good 35 HIGH No 0 n/a 36 LOW No 0 n/a 37 LOW Yes 8 Low 38 LOW No 0 n/a 49 HIGH Yes 32 Good 50 HIGH No 0 n/a 52 HIGH Yes 13 Good 53 LOW Yes 4 Low 54 LOW No 0 n/a 58 HIGH Yes 15 Good 61 HIGH Yes 1 Low 62 HIGH Yes 4 Low 64 HIGH Yes 29 Good 65 LOW No 0 n/a 69 LOW No 0 n/a 70 HIGH Yes 1 Low 71 HIGH Yes 8 Low 72 HIGH Yes 16 Good 77 HIGH Yes >10 Good 1 1 Pond 77 was only subject to torch surveys and so the population esiatme follows a precautionary principal and assigns a high value. Mouchel 2010 A.11T-12

13 Evaluation Analysis of results The field survey data supports the screening assessment work: significantly more smooth newts, and 100% of the ecologically significant smooth newt populations ( good populations), were recorded in ponds that were classified as being of high suitability for smooth newt. It is therefore reasonable to assume that the ponds within the study area that have potential to support significant populations of smooth newt have been identified and surveyed. Although smooth newts have been recorded in ponds that were classified as being of low suitability, when present they were only found in low populations, meaning such ponds are likely to be below the threshold classification for what warrants a significant biodiversity feature. Therefore, it is reasonable to assume that the smooth newt survey and assessment work that has been completed has successfully identified all smooth newt ponds within the study area that are likely to represent significant biodiversity features for consideration within the ES. Biodiversity value Although the smooth newt receives full legal protection in NI, it is currently not considered to be a rare or threatened species (O Neill et al., 2004). Therefore, in accordance with IEEM (2006), it is important to separate this legal status from any evaluation of the biodiversity value of the newt populations located within the study area. As no exceptional populations of smooth newt were recorded on site, it is unlikely that any of the smooth newt populations identified will be of national biodiversity value, despite the existence of national legislation that affords protection to all members of this species. It is also reasonable to conclude that as the smooth newt is a widespread species and is not currently rare or threatened, that low populations of this species are common occurrences and of no more than local biodiversity value. In contrast, good populations are likely to occur less frequently, and although such populations are unlikely to be features of national note, they are likely to be of note for the districts or counties in which they occur. It is suggested that as the peak count range of a good population of smooth newts is between 10 and 100, that those sites with greater than 50 newts recorded in a night are likely to be rarer and of biodiversity value at a county scale; while those ponds with between 10 and 50 newts observed are likely to be less valuable and of no more than district biodiversity value. Table 11T.3 and Figures in Volume 2, provide a summary of the likely biodiversity value attributed to the smooth newt ponds within the study area. It is reasonable to assume, with consideration of the field data findings, that smooth newts will either be absent from all low ponds that from were not selected for field survey or, if present, will only be found in low populations of no more than local biodiversity value. The ponds where newts were absent are of negligible value. Mouchel 2010 A.11T-13

14 Table 11T.3 Summary of the Likely Biodiversity Value of the Surveyed Ponds to Smooth Newt Pond Population Class Size Biodiversity Value 4 n/a Negligible 10 Good District 14 n/a Negligible 17 Good District 18 Low Local 23 n/a Negligible 25 Low Local 26 n/a Negligible 28 n/a Negligible 31 Low Local 33 Low Local 34 Good District 35 n/a Negligible 36 n/a Negligible 37 Low Local 38 n/a Negligible 49 Good District 50 n/a Negligible 52 Good District 53 Low Local 54 n/a Negligible 58 Good District 61 Low Local 62 Low Local 64 Good District 65 Low Negligible 69 n/a Negligible 70 Low Local 71 Low Local 72 Good District 77 Good District Mouchel 2010 A.11T-14