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M4 Corridor around Newport
PUBLIC INQUIRY QUESTION
REFERENCE NO. : PIQ /083
RAISED BY: The Inspectors DATE: 20/03/17
RESPONDED BY: Matthew Jones DATE: 03/05/17
SUBJECT: Bats Proof of Evidence Clarification
The attached document provides responses to questions of elucidation raised by Mr Wadrup in
correspondence dated 20 February 2017.
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Bats Proof of Evidence Clarification Richard Green BSc (Hons) CEnv MCIEEM
Contents
1. Introduction ....................................................................................... 2
2. Clarifications ..................................................................................... 2
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1. Introduction
1.1 This document provides a response to points of elucidation raised by Mr
Wadrup in correspondence dated 20 February 2017.
2. Clarifications
2.1. Evidence paras 7.8.13-16 Question: It would be helpful to have a map
showing where the bats are identified in numbers now (Magor lesser
horseshoe and Berry Hill common pippestrelle) and where, now, they fly
or commute to eg Wye Valley and Forest of Dean Sites , so the “barrier”
of the proposed road can be put into geographical context relative to
current hazards and alternatives to the published line.
2.2. Evidence paras 7.8.13-16 Response: Lesser horseshoe bats around
Magor. The figures below, taken from ES documents and edited for
clarity, seek to answer question 1. The following text explains the current
knowledge of bat movement in these areas. Figure 1 of the Statement to
Inform Appropriate Assessment (SIAA) show the location of the Wye
Valley and Forest of Dean SAC constituent sites in relation to the
Scheme and all lesser horseshoe bat survey records. Figure 3e of the
Statement to Inform Appropriate Assessment shows where the majority
of lesser horseshoe bat activity was recorded around Magor. It must be
noted that the number of bat passes does not necessarily equate with
number of bats but is simply a measure of activity.
2.3. We do not know if, how many, and along what route lesser horseshoe
bats from the Wye Valley and Forest of Dean Bat Sites SAC travel to the
Scheme area. We do know that lesser horseshoe bats fly under the
existing M4 using Mill Reen Underpass.
2.4. No lesser horseshoe bats were recorded during bat activity transects
during 2014. Static bat detector surveys in 2014/2015 were located
along the Scheme route and it is extremely likely that lesser horseshoe
bats also forage in the area away from the Scheme. The existing A4810,
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which is lit from the Magor interchange/Junction 23A to the South Wales
Mainline Railway and lies adjacent to the proposed line of the Scheme in
this area, provides a potential barrier to bats in this area. If crossing the
existing A4810 presently, bats are likely to be using the existing South
Wales Mainline Railway underpass on the A4810.
2.5. There are no known lesser horseshoe bat maternity roosts around
Magor. The only known lesser horseshoe bat roost is a ‘low-use’ day or
night roost that was found in February 2017, when internal access to the
coach house at Woodland House, Magor was arranged (a report will be
provided for the listed building inquiry in due course). Approximately 200
mixed age bat droppings were present in the building. Whilst this might
sound like a lot of droppings, it is indicative of occasional use over
several years by one or a small number of bats. Further survey on this
building is planned in summer 2017 to determine levels of use.
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2.6. Evidence paras 7.8.13-16 Response: Common pipistrelle bats
around Berryhill Farm. Figure 2e of ES Appendix 10.23 (on page 12 of
this document) shows relative levels of bat activity around Berryhill Farm
from static bat detectors in 2014 and 2015. Most this activity is from
pipistrelle bats. Pipistrelle bat activity has been summarised on the
Figure for this document.
2.7. The following italicised text is an extract from ES Appendix 10.7 at
paragraph 3.3.1, summarising bat survey findings for Transect 1 (2014;
refer to figures on page 13).
2.8. “Common and soprano pipistrelle were the most frequently recorded
species on Transect 1, although Myotis bats were also regularly
recorded on the Transect. Occasional passes of noctule (Nyctalus
noctula), Leisler’s bat (Nyctalus leislerii) and Nathusius’ pipistrelle
(Pipistrellus nathusii) were also recorded. Bats were recorded on all
parts of the transect with the main areas of highest bat activity around
Berry Hill Farm and the woodlands to the south of the farm and in the
fields to the west. Relatively high levels of activity were also recorded
along the A48 corridor in May and August although in other months the
levels were lower. Given the proximity of a known roost at Berry Hill
Farm the relatively high levels of pipistrelle bats is to be expected.”
2.9. It is not possible to know exactly where pipistrelle bats from Berry Hill
Farm and The Conifers maternity roosts fly to and along which routes.
However, it is reasonable to assume that bats will fan out from the roost
along hedgerows/tree-lined field boundaries and woodland, with bat
numbers diverging as distance from the roosts increases.
2.10. The main corridors and foraging areas are considered likely to be the
woodland and tree-lines to the south and east of Berryhill Farm, along
with the tree-lined A48 to the west. Similar behaviour is expected from
brown long-eared bats breeding at Berryhill Farm, although this species
is more associated with woodland and trees and tends to range over
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less distance from a maternity roost (most foraging activity observed
within 2 km of maternity roosts).
2.11. No bats were observed flying over the existing M4 using Pound Hill
Bridge during three surveys in September 2015. However, there is an
underpass under the existing M4 at Grid Reference ST 27233 84620
that has not been surveyed (refer to aerial photograph and Google
Street View below). The height marker on the underpass reads 14-0’, so
it is estimated that the underpass is approx. 5m w x 4.2 h. This could be
used by bats, including pipistrelles and brown long-eared bats from
Berryhill Farm to access woodland foraging habitat to the north of the
existing M4. Bat survey at the culvert could be undertaken this season
(from April 2017) to confirm bat use.
Location of underpass (Point B) under existing M4 in relation to Berryhill Farm
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View of underpass from the south
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2.12. Para 7.8.12 Question: What evidence substantiates your claim of “over
evaluation”?
2.13. Para 7.8.12 Response: As stated in 3.4.2 & 3.4.3 of my proof, Wray et al. state
that their approach should be used as a framework rather than a rulebook.
Their approach was the first attempt in the UK to assign values for bat in EcIA,
and although not strictly a recognised standard, it has been adopted by
ecologists, as published in the CIEEM journal ‘In Practice’ (December 2010), in
the absence of any alternative.
2.14. The method of evaluation relies heavily on knowing the approximate number of
bats (individuals, small number or large number) using a commuting route or
foraging area. Unfortunately, without direct observation, it is impossible to
determine the number of bats foraging in an area. Even with direct observation,
if an individual bat flies out of sight and then returns, it is not possible to be
certain if this is one or two bats. It is also impossible to observe bats effectively
after dusk and before dawn, when it is too dark to see them. Static bat
detectors are therefore a suitable alternative for measuring bat activity.
However, activity level is all that can be deduced from their recordings. They
cannot count individual bats. Where high levels of bat activity are recorded, it is
impossible to say whether this is due to a high number of bats flying past or one
bat foraging for a prolonged period in the same area, repeatedly flying past the
bat detector, which records each pass.
2.15. Pipistrelle bats have relatively loud calls and are readily recorded by bat
detectors. They also have a habit of foraging in the same location for prolonged
periods, particularly along the edge of tree canopies and tall hedges, and
around street lights, as they feed on the insects attracted to them. In my
experience of undertaking an extensive amount of bat activity survey, other
species that forage for prolonged periods in an area include Myotis and
serotine bats and to a lesser extent, barbastelle, noctule and Leisler’s bats,
particularly when foraging along hedgerows. In my experience, long-eared and
horseshoe bats tend to be more wandering species, not repeatedly flying up
and down the same hedgerow for extensive periods. Some bat species, e.g.,
long-eared, have very quiet calls and therefore may be under-recorded.
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2.16. Therefore, it is very difficult to determine even an approximate number of bats
commuting or foraging, e.g., along a hedgerow/reen. The following activity
levels were used to assign ‘number of bats’ in the valuation for bats in the ES.
Over, on average, 100 passes per night = large number; on average, between
10 and 100 passes per night = small number; and on average, less than 10
passes per night = individuals. This is a reasonable conversion but as there is
no way of confirming numbers, the valuation could be grossly affected by an
over (or under) estimation. It would not take long for one bat to generate 100
bat passes when foraging up and down the same hedge repeatedly. One pass
does not even equate to one actual pass of the detector, as it is possible for the
detector to record two or more passes as the bat approaches and passes the
detector.
2.17. Therefore, the assessment based on bat activity alone could be misleading and
the landscape is an important consideration in valuing the area for bats. As
discussed in paragraph 3.4.3 of my proof of evidence [WG 1.20.1] the fields
between the hedges and reens over the levels are unlikely to provide valuable
bat foraging habitats. It is acknowledged that the hedges/tree lines and reens
do provide a valuable habitat network but when one considers the results of the
walked transect surveys, the more open and exposed areas over the levels
tended to have less bat activity. The highest levels of bat activity tend to be
found where there is more tree cover.
2.18. As the valuation for bats uses a geographical reference, I looked at the area
around Newport and South Wales using aerial photography on Google Earth.
For the most part, excluding cities and large towns, South Wales contains a
relatively high density of woodland compared to the rest of the UK, and also
comprises of a patchwork of many small fields bounded by a network of hedges
and tree lines. There are also many wooded valleys and river systems. These
habitats provide favourable habitats for bats because of a high insect
abundance and diversity and, in particular, more shelter from the wind than
would be present on the levels, meaning that prey availability is likely to be
greater on average, as open habitats provide little available insect prey in windy
conditions. Therefore, if one considers the valuation of bat foraging habitat
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based on habitats available in the region, rather than just basing it on numbers
of bat calls recorded on bat detectors, the Levels are, in my opinion, likely to be
less valuable than other areas in South Wales. Coupled with this, the areas at
each end of the Scheme are currently subject to ‘disturbance’ and habitat
degradation from the existing M4 and A-roads, industrial areas and housing
development, whilst Newport docks provides low value bat habitat.
2.19. I suspect that if similar bat survey was undertaken across the whole of Wales
(excluding urban areas and coastal habitats), the whole of Wales would be
valued (using the Wray et al. method) as of at least regional value. If the
purpose of having a geographical frame of reference for valuation is so that one
can identify the most important areas for bats within a larger area, such as the
‘region’, my suggestion that the Scheme corridor may be of county value seeks
to compare the area with the rest of the ‘region’.
2.20. I have already raised in my proof of evidence [para. 3.4.3 of WG 1.20.1] how
the presence of one greater horseshoe bat over all of the surveys undertaken
assigns a level of regional value for this species. Whilst rare, individual greater
horseshoe bats are wide ranging. For example, an individual bat ringed in
Gloucester was subsequently found in North Wales. Therefore, the greater
horseshoe bat recorded could simply have been ‘passing through’ or exploring
the area, rather than regularly foraging in the area.
2.21. In consideration of barbastelle bats, another species considered in the ‘rarest’
category, whilst rare, this species is found across Wales and southern and
central England and it is not unusual to record this species when undertaking
such extensive bat survey as has been undertaken for this Scheme. Whilst
there are records of barbastelle, particularly at the eastern end of the Scheme,
the activity levels recorded are low (0.03 – 0.4 passes per night on average)
and ignoring the method of assessment proposed by Wray et al., it is hard to
see why such low levels of activity would justify the area being of regional value
for this species alone. The same applies to Nathusius’ pipistrelle.
2.22. Other species listed as ‘rarest’ in Wales include whiskered bat. This is a Myotis
species (Myotis mystacinus). Myotis bat species are very difficult to differentiate
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by bat detector, as there is considerable overlap in call structure. For this
reason, the assessment has not differentiated between Myotis species and this
species group has been collectively considered as within the rarest category.
Whiskered bats are distributed across Wales and England and into Scotland
and it is extremely unusual not to record Myotis bat species when undertaking a
bat survey such as this anywhere in Wales. The same is true of noctule bat.
2.23. Table 1 from Wray et al. shows how bat species are categorised, according to
distribution and rarity. This is included below, along with distribution maps of
mentioned species.
2.24. Despite my suggestion that the Scheme corridor may be of county value for
bats, I acknowledge that up to 14 species have been recorded in the area,
including rare species, such as both horseshoes and barbastelle bat, and do
not disagree with the precautionary approach of valuing the Scheme corridor as
of regional value for bats but simply raise the issues of determining value using
the Wray et al. model to demonstrate that a precautionary approach has been
taken to the valuation and impact assessment.
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Barbastelle bat distribution – taken from https://data.nbn.org.uk
Nathusius’ pipistrelle distribution – taken from http://www.nathusius.org.uk
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Whiskered bat distribution – taken from https://data.nbn.org.uk
Noctule bat distribution – taken from https://data.nbn.org.uk