Reptile Mitigation Guidelines 1st Edition
Reptile Mitigation Guidelines 1st Edition
Reptile Mitigation Guidelines 1st Edition
Background
All of our reptile species have suffered declines,
to varying extents across the country. For the
widespread species, most populations of which
occur outside protected sites, development
without adequate mitigation continues to be a
significant reason for this decline.
The emphasis in this guidance is on what are have developed specific guidance, for example
known as the widespread species. Generally the on the survey effort scoring system.
rare species are restricted to protected sites and
therefore developments rarely affect them. We welcome feedback and may update this note
However, where appropriate some advice on the with more detailed information as resources and
rare species is given. evidence allows. Other organisations may also
provide guidance to expand on this document
For ease of reading, development in this and if this happens references will be updated.
document has a broad meaning, referring to any
land use change that might negatively impact on The recommendations should be suitable for the
reptiles, whether subject to planning permission majority of mitigation situations, but this is not a
or not. Typical examples are road widening, set of rigid rules, nor an exhaustive guide.
construction of residential properties and Where other methods and approaches are
improvement of drainage structures along known to work well, please provide details to
railways. help us improve future editions. See Further
information below for contact details.
This document is not intended to provide advice
on impacts caused by conservation Where there are particular local circumstances
management, forestry, farming or other ongoing which require the use of alternative levels of
activities. effort, timing, methods or strategies, a rationale
based on the site circumstances will help to
Reptile mitigation has been practised for around demonstrate that the mitigation plan chosen is
20 years in England, with greatly increasing sound. In some cases it may be necessary to
frequency over the last 5 years. Statutory and show this to meet legal requirements.
non-statutory guides have helped establish
standard methods, though these documents Natural England and others may view
typically focus on particular elements of unfavourably any attempts to use reduced
mitigation. This note draws together existing standards solely for reasons of cost,
guidance, recent research findings and field development time constraints or to
observations, to produce a single set of accommodate a larger development footprint.
standards for good practice. Much of the advice
is derived from recommendations from Advice for planners and local
experienced ecological consultants.
authorities
Natural England has published this guidance It is important that planners and others working
following discussions with a range of people with the planning system appreciate that the
involved in reptile mitigation. It is intentionally legal protection for reptiles is only one element
concise, focusing on mitigation principles and to consider in development control and forward
technical standards. For general background on planning.
reptiles and legislation, please refer to standard
texts and internet resources. Notable references Legislation prohibits certain actions, and
are mentioned in Further reading below. planning decisions must take account of this. In
addition Local Planning Authorities are also
This note aims to provide the high level obliged to take a wider view of reptile
guidance that has been identified as critical. conservation when undertaking their functions.
Consultation has also identified a need for highly This obligation stems from Section 40 of the
prescriptive guidance on methods and effort, but Natural Environment and Rural Communities Act
this demand cannot be met for all topics, partly 2006, and the fact that all native reptiles are now
due to limited resources and partly because the BAP priority species.
evidence base for some areas is sparse, and
setting guidance in such a situation would be
unwise. Where there is reasonable evidence, we
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Government policy is clear that planning assessments and mitigation proposals submitted
decisions must take account of protected with applications. Further advice on considering
species (Planning Policy Statement 9: reptiles in planning is available on Natural
Biodiversity and Geological Conservation; Englands website, notably in relation to
hereafter referred to as PPS9). Standing Advice.
This clearly has further reach than solely Consultants vary in their experience of reptiles,
assessing whether a breach of the legislation and when employing a consultant you should
might occur. Planners would be justified in request evidence of favourable outcomes for
rejecting a mitigation proposal if it would have a reptiles in several recent projects. Other
negative effect on local reptile conservation indicators of a capable consultant include
status, even if the project involved no breach of membership of a professional body, and
the wildlife legislation. This applies to both the demonstrable contribution to reptile conservation
widespread and the rare species. and monitoring projects.
Exceptions for widespread species only To protect reptiles from any harm that might
If the act was the incidental result of a lawful arise during the development work.
operation and could not reasonably have been To ensure that there is no net loss of local
avoided (Section 10(3)(c) Wildlife and reptile conservation status, by providing
Countryside Act 1981 (as amended)). sufficient quality, quantity and connectivity of
habitat to accommodate the reptile population
Exceptions for rare species only in the long term, either on site or at an
If the act is permitted under a licence issued alternative site nearby.
under Regulation 53(2)(e), ie for the purpose of
preserving public health or public safety or other These objectives should be used by consultants
imperative reasons of overriding public interest to frame the mitigation and set specific aims for
including those of a social or economic nature every project, taking into account the particular
and beneficial consequences of primary circumstances of the site and the development
importance for the environment. proposals. Concisely setting out aims will help to
produce an effective mitigation plan. It will also
Key points arising from the legal ensure that the developer and other interested
protection are: parties can rapidly understand the rationale for
the mitigation.
For all species: if a development has potential
to impact reptiles in a way that could cause an Mitigation must be proportionate and pragmatic.
offence, efforts must be made to reduce, and if This must be considered when setting objectives
possible, avoid those impacts. and implementing mitigation plans.
For the widespread species: actions which
could predictably kill or injure reptiles may
result in an offence, even if that outcome is not
the prime purpose of the act. We therefore
advise developers to use this guidance, along
with advice from a consultant, to ensure they
take reasonable measures to avoid harm. No
licence is required for standard mitigation
methods.
For the rare species: the legislation is stricter
than for the widespread species; both the
reptiles themselves and elements of their
habitats are protected, and there is no
statutory defence. Unless direct impacts can
be avoided, a Regulation 53(2)(e) licence from
Natural England will normally be required. See Fencing can prevent reptiles entering areas subject to
earthworks or heavy plant movements
Further information below on European
Protected Species: mitigation licensing. Example mitigation aims
The following works were identified to protect
Penalties for breaches of legislation are up to slow-worms and common lizards at Sauria
5000, and/or up to 6 months imprisonment Common during archaeological investigations
(each per offence). In addition, anything used in
and the construction of a new car park:
committing the offence may be forfeited. The
main legal protection applying to reptiles is
Erect fencing to exclude reptiles from the
outlined in Table 1 on page 22.
working areas and relocate any reptiles in the
working areas to safe areas.
Mitigation objectives The footprint of the new car park to be limited
Overall objectives for all reptile mitigation to areas of low to medium value for reptiles.
projects should be: Create new basking, feeding and hibernation
habitats for reptiles along the northern edge of
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the site where the land is currently of low value For records of the rare species, the NBN
for reptiles. Gateway has good general coverage, and
This new habitat to link to the habitat north of Amphibian and Reptile Conservation can
planned car park (maintain existing link). provide more detailed information.
Create a link from the new habitat to the
Country Park to the east. The main field methods used for reptile surveys
in a mitigation context are summarised in Table
All existing and retained reptile habitat to 2 on page 23. Note, these methods all require
continue to be under favourable management.
an experienced surveyor.
Survey methods Roofing felt in suitable micro-habitats can help to survey for
Desk searches for the results of past surveys at reptiles
or near the site can be very useful. Sources Table 3 on page 24 shows some examples of
include: survey methods that may be used as a
supplementary field survey, alongside one or
The National Biodiversity Network (NBN) both of the methods in table 2. The methods in
Gateway (http://data.nbn.org.uk). table 3 are generally of lower effectiveness and
Local Records Centres (www.alerc.org.uk, prone to false negatives, but may be worth
www.nfbr.org.uk). attempting in many cases.
Amphibian and Reptile Groups
(www.arguk.org). Pitfall trapping is not recommended because it
would require leaving traps open during the day,
Widespread reptiles are under-recorded in most creating an unacceptable risk to reptiles and
parts of England and the lack of a record is not a non-target species.
reliably indication of absence.
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The effectiveness of the survey methods varies within which surveyors should select the
considerably by species. Table 4 on page 25 appropriate timing for their particular survey.
assesses and summarises the two most
effective survey methods. Time of day: 0700 to 1800, on the condition that
date and weather conditions (see below) must
also be suitable throughout the duration of the
survey visit.
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successful in slightly cooler conditions than successful than an identical visit in May.
those indicated above. Therefore surveys early in the year need more
effort (ie more visits) to be reliable.
Choosing a survey protocol
Deciding what type of survey to undertake will Each species has a recommended minimum
depend on a range of considerations. Table 6 on number of standard effort units, ranging from
page 26 should help you decide survey protocol. 25 to 50, as displayed in Table 7 on page 27.
This table also gives the recommended survey
The first step is to assess what broad impact the methods. Table 8 on page 27 gives monthly
development might have on a population, if one effort weightings. Notes on how to use the
were present. Assigning a development impact tables and a worked example are available
category is covered in the Impact assessment below table 8.
section below. The different types of survey,
including HSA (habitat suitability assessment), Population size class assessment
are also covered below. Note that where Determining the size of a reptile population is
different types of survey are indicated (for difficult without substantial effort. However, in
example, presence/absence + population size many cases a precise estimate of population
class), the survey effort can be combined, ie you size is not required for an impact assessment
do not need to conduct two separate sets of and mitigation planning. It can be useful, though,
surveys. to obtain an assessment of the population size in
very broad terms, ie small, medium or large.
In addition to the survey types below, there will Here, this is termed the population size class.
often be a need for a targeted survey to
establish key areas of a site (such as egg-laying Note that this classification and the methods to
or foraging habitat). This helps to assess a site's assess it are based on limited data and will be
value for reptiles, and to design mitigation that refined in future. Table 9 on page 31 gives a
will properly address this. method for categorising population size classes.
There are two methods for determining
Presence/absence survey standards population size class:
The true absence of a reptile species is
extremely difficult to establish with high Method a: peak count: For each species, the
confidence. However, for ease of terminology, a first figure is the peak count of adults obtained
survey to determine presence or likely absence by a thorough survey (by whatever method)
will be termed presence/absence survey here. under good conditions in one day, and at the
optimal time of year for the target species.
For each species possibly present, the survey These figures can be derived from your
may cease once the species has been detected. presence/absence survey or from another recent
Note that the standards for effort given here are survey done to a sound standard.
minimum values. Research shows that detecting
reptiles, especially where they occur in small Method b: habitat suitability assessment:
populations, can require substantial effort. The Establish the presence of the species and then
surveyor should increase the level of effort assign a population size class estimate on the
beyond these minima if, despite zero captures, basis of a habitat suitability assessment.
there are indications of likely presence.
For a given site and species, if there is a
How to calculate minimum effort in terms of the discrepancy between the count-based method
number of days of survey, and visits through the and the habitat suitability-based method, the
season is explained on page 25 and the highest population size class should be chosen.
following pages. This takes into account the fact For instance, if a peak of only 11 slow-worms is
that the chance of detecting reptiles varies found, yet the habitat suitability assessment is
substantially between species and across the exceptional, then you should categorise the
survey season. For example, one visit to detect site as having a large slow-worm population.
slow-worms in March is much less likely to be
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This precautionary approach is advised because this approach and it is strongly discouraged,
of the complex relationship between numbers of unless the surveyor has a detailed
animals detected during surveys and the actual understanding of the ecology of the specific
population size. Whilst not a perfect method of population and can demonstrate that the
assessing population size class, it will give an resulting estimate is sound.
indication of the potential for the species on the
site, which is the main objective of establishing Habitat suitability assessment
the population size when assessing impacts and Making an assessment of habitat suitability can
planning mitigation. be invaluable in interpreting survey data, risk
assessment, impact assessment, planning
Estimating population size capture schedules, and planning habitat
Population size can be estimated by CMR enhancement works.
(Capture-Mark-Recapture) techniques.
For some species, for example the great crested
newt Triturus cristatus, a thoroughly tested,
objective method has been published, using
methods developed by the US Fish & Wildlife
service. As yet, no such method exists for UK
reptiles. The following bulleted list, gives
characters that influence reptile habitat
suitability, and this can be used to develop an
assessment method for a specific situation. It
may help to read guidance on reptile habitat
assessment produced for the National Reptile
Survey, part of the National Amphibian and
Reptile Recording Scheme (see Further
information below for details).
Registering slow-worm head pattern Natural England would value information on any
assessment methods used, to help us publish a
It is generally difficult to obtain a robust estimate
more detailed, thoroughly tested method in
of reptile population size with modest confidence
future.
limits unless the population is small and isolated.
A walk-over survey will allow a competent field
The best results are typically obtained for the
worker to gauge these 12 characters and give a
adder. This species often occurs at rather low
whole-site assessment as poor, good or
population density, can be located seasonally
exceptional for uniform sites. For sites that vary
with confidence, and individual identification is
substantially in nature, and especially for large
feasible using head patterns.
sites, it will be more appropriate to produce a
Deriving a population size estimate by CMR is map subdividing the site into distinct areas on
encouraged wherever feasible on high impact the basis of their suitability. Each area can then
schemes, as it can be very useful for planning be assigned to one of these three categories.
mitigation projects.
A simple habitat suitability assessment should
Exhaustive surveys (say over 20 visits per take as long as it requires to do a slow walk-over
season, with a high density of sampling points) survey, plus a few hours to analyse your
may also help to derive a population estimate. observations.
This method is highly time-consuming and often
a CMR approach would yield a better result.
Reptile habitat characters
location in relation to species range;
Population estimates based on habitat extent vegetation structure;
and theoretical population density are often insolation (sun exposure);
unreliable. There are considerable problems with
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Indirect impacts
Disturbance.
Refuse accumulation.
Fire risk.
Persecution, collection and predation.
Hydrological disruption.
Table 10 on page 32 advises on how to assign a
broad impact level to the proposed development.
Once the potential impact on reptiles has been
identified the sequence of steps should be as
follows.
Grass snake egg laying site
Mitigation strategies Grass snakes are highly mobile and may require
a different approach to slow-worms or sand
Once the possible impacts have been examined, lizards, which move over much shorter
the mitigation strategies should be considered. distances. Sand lizards and adders may be
The main strategy options are in Table 11 on more prone to public disturbance effects than
page 33. As each case is different some options the other species.
may need to be mixed to reach a favourable
outcome. In general, the options become
increasingly undesirable towards the end of Receptor site selection
table 11. Note, the least desirable options, A receptor site is the place where reptiles are
involving non-adjacent relocations, may not be released after capture. This may be adjacent to
agreeable to Natural England and the Local the point of capture (often just outside the
Planning Authority as they involve a greater risk development footprint) or some distance away.
that there will be a negative effect on reptile Choosing and preparing a suitable receptor site
conservation status. There would need to be a is critical to the success of reptile mitigation.
sound justification for why all other options had
been exhausted before these options could be Finding a suitable receptor site is often a lengthy
pursued. process and developers should allow substantial
time for this. Unless a site has already been
Reptiles should only be moved to a non-adjacent lined up, surveys of several sites may be
site (ie one outside the normal home range) required, and this will take time. Often the best
already containing the same species when: approach will be to score each possible receptor
site using the criteria described below, and
there is no viable on-site solution; select the highest-scoring site.
only small numbers are predicted to be moved
(say <50 individuals); Selecting a receptor site well in advance will
make subsequent mitigation efforts proceed
habitat enhancement, creation or restoration more smoothly. Depending on the type of habitat
works at the release site are undertaken which
enhancement or creation required, it will
are likely to substantially increase its carrying
normally take at least months and possibly
capacity; and
several years to bring a receptor site into a
there would be no net loss to local condition suitable for receiving reptiles. Only in
conservation status. limited cases are little or no habitat works
required before reptiles can be received.
The species will affect the mitigation strategy.
For example adders appear to be closely linked Leaving receptor site selection until late in the
to traditional hibernation sites, and relocating planning process may cause delays and
them to non-adjacent areas is almost never potentially substantial additional costs. The
appropriate. receptor site should be agreed before submitting
the planning application because it forms a key
element of the mitigation plan.
This receptor site is becoming overgrown and will need SSSIs and other strictly protected sites are
management before reptiles can be released almost never to be used as receptor sites. This
is because they will normally have particular
Receptor site checklist conservation objectives which might be
interfered with if reptiles are released, and
You must consider the following factors when
because in any case, if broadly suitable, they will
assessing potential receptor sites.
typically already support reptiles. Whilst SSSIs
Location can seem attractive options, in some local areas
there has been a contraction in reptile range as
To help achieve the objective of no net loss to developers progressively shift reptiles onto
local reptile conservation status, the receptor protected sites. It is important that reptiles are
site must be as close as possible to the retained in the wider countryside. In rare cases it
development site. In most cases, the best may be acceptable to release reptiles on a SSSI:
interests of the reptiles will be served by an in
situ approach. This means either (a) keeping there must be no other practical options;
them on part of the site that will retain good
habitat, or (b) relocating them to an area
the release would be consistent with the sites
conservation objectives, and
immediately adjacent to the development site.
there has been agreement with Natural
In all cases, reptiles should not be translocated England and the landowner/occupier.
to sites a long distance away, say over 20 km.
There is a presumption against translocating Size
reptiles outside the Local Planning Authority The amount of habitat suitable for the species to
area. If it is unavoidable that reptiles are moved be relocated should be no less, and preferable
to a new LPA area, any mitigation and post- greater than, that to be lost through
development works must be secured through a development. The amount should be assessed
Section 106 Agreement or other mechanism that either (a) as it currently stands before the
can be enforced outside the original LPA area. mitigation (if the site is already suitable), or (b)
after any habitat enhancement and creation
The primary reason for this is that it results in a works (if such works are necessary, as will often
net loss to local conservation status. Other be the case).
concerns relate to the potential for detrimental
impacts at the receptor site either on the For the widespread species, some reduction in
translocated animals or any already present - area may occasionally be acceptable if you can
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ensure the quality of the habitat will be numbers, do not make the common mistake of
substantially higher than that to be lost. The asserting that adding more reptiles is acceptable
advice above on habitat suitability assessment, because the population is below carrying
can help in this regard. capacity. This logic is flawed because it relies
on a misunderstanding of the carrying capacity
Habitat status and connectivity concept, and ignores the issue of local
The habitats should either be already suitable for conservation status.
the species to be released, or capable of being
made suitable. This assessment should go Carrying capacity depends on a range of factors,
beyond general suitability, and ensure that the notably habitat extent and quality. Reptile
site includes all necessary features to support a populations will vary in size over time.
population of at least equivalent status to that at Relocating more reptiles to an occupied site
the donor site (see Habitat suitability without attempting to increase carrying capacity
assessment, above). Moreover, there should will result in a net loss in reptile status, and is
generally be attempts to improve the extent and therefore unacceptable. The key point is to try to
quality of habitats prior to relocating reptiles. increase the carrying capacity by improving
habitat conditions.
No reptiles should be released until the site is in
a reasonable state to receive reptiles. Some Number of receptor sites
management works may be undertaken post- Generally, a single receptor site should be used
release to further improve habitat quality, so long to accommodate each development site lost.
as they do not pose a serious risk to reptiles or The rationale here is that splitting the donor
other sensitive species. The site should be in reptile population between multiple receptors will
favourable management or be capable of being result in more population fragmentation, when
brought into such a state (see below). compared to the original situation. Exceptions to
this may be indicated if, for example, large
Receptor sites should be well connected to numbers of animals are predicted to be removed
semi-natural habitats, and particular attention from a large development site, and you have
must be paid to grass snake relocations given located two or three similarly large receptor sites
the long distance dispersal behaviour of this that are also highly suitable in all other respects.
species. If it is impossible to retain good In such cases, if feasible there should be
connectivity in situ, then an ex situ (non- attempts to link the receptor sites over time.
adjacent) receptor site may be more suitable. Using more than three receptor sites would
almost never be advisable.
Prey availability
Generally speaking, for relocations of any of the In rare cases, reptiles from several development
lizard species, prey diversity and abundance is sites might be released at a single receptor site.
likely to be adequate as long as the receptor site This can be acceptable where the site is large
habitat quality is high. For the snakes, more and there is good connectivity.
investigation may be needed in some cases.
You must be confident that the receptor site Site safeguard and long-term
accommodates the rather more specific diets of management
adders, grass snakes or smooth snakes. Receptor sites should be free of foreseeable
threats. The most obvious point to check here is
Reptile status threats due to future planning applications. You
This depends on which mitigation strategy you should check with the relevant strategic plans
opt for (see above). In most cases, it is that the site is in an area that makes this
preferable for the receptor site not to support the unlikely. For example, consider possible
species to be relocated. You should either know, residential, industrial, commercial, minerals,
or try to infer, the reasons for this absence, and road and rail developments.
be able to remedy them. If a receptor site survey
demonstrates reptiles are present in low
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You should send a record of the receptor site to For in situ schemes: critically assess the
the Local Planning Authority and recommend features that would be lost or damaged. How will
that it is marked on planning alert maps. these be replaced on the habitat to be retained?
For example, if the development will destroy a
Ideally receptor sites should have some form of bank frequently used for basking in late
formal protection from future development, afternoon, then ensure a similar one is created
possibly via site designation. A frequently used (with the right orientation, etc) on the receptor
method is designation as a Local Wildlife Site site.
(often called County Wildlife Site, Site of
Biological Interest, etc). For ex situ schemes: Here the task is more
complex as the works will have to create or
Other options for site safeguard include Section restore all the requirements for the target
106 agreements and restrictive covenants. You species.
should also consider any other threats outside
the planning system and relevant to the area, Precise methods for creating or improving
such as forestry operations or increased habitat will depend on the target species and the
recreational use. site conditions. Guides to habitat management
may help particularly Edgar et al, 2010; see
It is critical that alongside ensuring site security, Further reading below.
there is a mechanism to guarantee favourable
habitat management. These include: General principles of habitat
enhancement
Section 106 agreement; Maximise the amount of insolation (sun
legal agreement with landowner; exposure). Ensure reptile areas are not shaded
transfer of ownership or leasehold to a land by trees, buildings or fences. Include south-
management company; and facing slopes, particularly where these can be
contract with land management company or juxtaposed with other habitats and features of
conservation organisation. value
The level of effort to achieve this will depend on Incorporate as much small-scale variation in
the impact of the development and the topography and exposed substrates as is
importance of the population. Whichever feasible. Introducing patches of low-nutrient sub-
mechanism you choose, funding for the long- soil as a surface treatment in areas otherwise
term management of the receptor site must be covered with topsoil can be a helpful method of
secured from the developer (unless only minimal creating structurally-diverse habitats
impacts are predicted).
Ensure there is a high level of structural variation
Habitat creation, restoration in vegetation. This may mean ensuring
landscape planting schemes develop a mosaic
and enhancement of different vegetation types
Ensuring reptiles have access to good quality
habitat is critical to achieving a favourable It may be worthwhile, especially on large sites,
mitigation outcome. The best way to do this will to create release focal points where reptiles
depend on the circumstances. The following are released. These should be sited away from
principles may help. public areas. They should contain plenty of
refuge habitat such as brash piles or bramble
Assess the current condition of the site patches, have excellent vegetation structure,
depending on the ecology of the target species and be in areas of high insolation for much of the
and the habitat suitability assessment. day. In this way, stress levels will be reduced
Determine the currently favourable and when the animals are released. These areas can
unfavourable characters of the site. also be useful for monitoring.
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Ensure the development layout does not affect Capturing adders requires particular care to
connectivity between habitat features. ensure the welfare of both the fieldworker and
the snakes. Experienced fieldworkers often use
Avoid planting schemes that will predictably snake hooks or specialist puncture-resistant
result in high shading levels in key areas, except gloves that also cover the forearm. Snake tongs
where there is a reliable long-term habitat are not advised as there is a higher risk of
management mechanism. harming the animal. All fieldworkers who would
potentially capture adders should be trained in
Create substantial features such as large safe handling methods, first aid and emergency
hibernacula in purpose-built embankments, procedures. A risk assessment should be
which link with other boundary features. undertaken and hazard reduction measures put
in place.
Restore degraded areas by reducing dense tree
and scrub cover. Locating reptiles for capture should follow the
advice in survey methods, above. For those
species more easily found using artificial
refuges, you should use a very high refuge
density (minimum 500/ha, ideally 1000/ha of
potential habitat where conditions indicate this is
merited) as this will increase capture rates over
the densities typically used for surveys. Using a
high density of refuges is especially useful for
capturing animals unlikely to move far, such as
juvenile lizards. It can also result in more rapid
population depletion.
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All field gear must be regularly disinfected to piles and bramble-covered banks. Hand
minimise the risk of causing disease in wild searching that does not carry a high risk of injury
reptile populations. Ideally, people who keep to reptiles can be done at any time in the capture
non-native species should not undertake reptile period. Otherwise, it should follow a standard
capture. If they do, they must take stringent capture programme using methods described
precautions to avoid transmitting disease. above.
Using temporary fencing and vegetation Destructive searching is a potential harmful and
management to help capture often unproductive method that has been
It may be helpful to divide up sites with fencing overused in mitigation practice. It involves using
to increase capture efficiency. In most capture machinery to dismantle structures or excavate
projects you will need a perimeter fence to substrates to reveal sheltering reptiles. They can
prevent re-colonisation. Installing fences (one- then be captured by hand. The degree to which
way or otherwise) between different phases of a this is possible will vary significantly from site to
phased development can often be useful as it site and there may be overriding (human) health
permits a concentrated capture effort within the and safety considerations which constrain such
first phase areas, where access for construction activities. In some exceptional situations a
purposes is required earlier than for the rest of destructive search can be helpful in removing
the site. Fencing may not be needed if the site the last few individual reptiles without
will be stripped bare immediately after the compromising their welfare. Generally the best
capture period, and re-colonisation is unlikely. approach to adopt is to begin the search in a
On small, sensitive sites, the risk of harming very careful and precautionary manner, and
reptiles through fence installation may preclude gradually increase the speed of the operation if
its use. no reptiles are found.
extents of uniform habitats such as grassland, Occasionally temporary holding areas may be
heathland or scrub. Removing reptiles from such necessary if genuine emergency works require
areas using standard capture methods is more rapid removal of reptiles, for example when
effective and carries lower welfare risks. contaminated land is discovered.
Transporting reptiles, captivity and In some cases, for releases from mid-August
temporary holding areas onwards, it can be helpful to release reptiles into
Immediately after capture, reptiles should be a small fenced area within a large receptor site,
placed in a cloth bag secured with a plastic clip to ensure that they stay close to the intended
(snakes and slow-worms) or a small closable hibernation site. In all cases of such temporary
box (legged lizards). Adders should be then be fencing, the consultant must take responsibility
placed in a box that is rigid, thoroughly escape- for removing the fence as soon as its function
proof, lockable and clearly marked Caution: has ceased.
venomous snakes. Any vehicles used to
transport adders should be similarly marked. Timing and effort in capture programmes
The other species can be placed in lidded Table 12 on page 35 below gives a matrix for
buckets or similar containers, lined with determining minimum capture effort. This
vegetation to provide a soft base. method was developed to help consultants take
into consideration the main factors that affect the
Different species should be kept separately. depletion of reptiles in typical removal projects.
Smooth snakes and sand lizards should be kept These factors are:
individually in separate bags. The time between
capture and release at receptor site should be Species score: a weighting combining the
minimised, with 4 hours as a maximum. Take typical catchability of the species with its
particular care over transport in especially high conservation and legal status (note that this
or low temperatures. Reptiles must not be score has no applicability beyond the specific
released in cold weather, and so you may need use in this table).
to retain them overnight if temperatures fall Site size: the area of the land from which
suddenly. reptiles are to be removed; typically equates to
the development footprint, but it may be more
Finding and preparing a suitable receptor site in or less depending on mitigation strategy.
good time means that captured animals can be Population size class/ Habitat Suitability
released within hours of removal from the Assessment: a weighting for the population
development site. Retaining reptiles in captivity density of reptiles in the capture area.
for more than one day is not advisable in Whichever of these two values gives the
mitigation projects. Captive over-wintering of higher score should be used in this calculation.
reptiles as part of planned mitigation is never For large sites with highly variable habitat
acceptable. suitability, make an informed choice of which
score best represents likely reptile population
Occasionally, reptiles are discovered
density.
inadvertently during works ie their discovery and
capture is not part of planned mitigation. In such Additional comments on capture
cases, it is normally possible to release them
programmes
close by. As a last resort they can be brought
into captivity, including over-wintering, if Capture is not normally advised to mitigate for
absolutely necessary. Note that for the rare negligible impacts so long as no offences
species there are legal issues to consider here would be committed.
(capture, disturbance and possession, and
Calculations recommended here give the
potentially damage to habitat).
minimum effort, and in many cases the actual
Do not retain reptiles in temporary holding areas period will be longer due to local conditions.
when their final destination is uncertain. Such
practice must be avoided by careful planning.
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English Nature. 1994 et seq. Species Joint Nature Conservation Committee. 2004.
Conservation Handbook. English Nature, Common Standards Monitoring guidance for
Peterborough. reptiles and amphibians. Joint Nature
Conservation Committee, Peterborough.
English Nature. 2004. Reptiles: Guidelines for
Developers. English Nature, Peterborough. KRY, M & SCHMIDT, BR. 2008. Imperfect
detection and its consequences for monitoring
FEARNLEY, H. 2009. Towards the ecology and for conservation. Community Ecology 9: 207-
conservation of sand lizard (Lacerta agilis) 216.
populations in Southern England. Thesis for the
degree of Doctor of Philosophy, University of KRY, M. 2002. Inferring The Absence Of A
Southampton. Species - A Case Study Of Snakes. Journal Of
Wildlife Management 66: 330338.
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KYEK, M, MALETZKY, A & ACHLEITNER, S. support of the National Amphibian and Reptile
2007. Large scale translocation and habitat Recording Scheme (NARRS). Unpublished
compensation of amphibian and reptile report to Esme Fairbairn Foundation.
populations in the course of the redevelopment
of a waste disposal site. Zeitschrift fr SHELDON, S & BRADLEY, C. 1989.
Feldherpetologie 14: 175190. Identification of individual adders (Vipera berus)
by their head markings. Herpetological Journal
MOULTON, N & CORBETT, K. 1999. The Sand 1: 392-395.
Lizard Conservation Handbook. English Nature,
Peterborough. SHOWLER, DA, ALDUS, N & PARMENTER, J.
2005. Creating hibernacula for common lizards
ODPM, Defra & English Nature. 2006. Planning Lacerta vivipara, The Ham, Lowestoft, Suffolk,
for Biodiversity and Geological Conservation: A England. Conservation Evidence 2: 96-98.
Guide to Good Practice. ODPM.
STEBBINGS, RE. 2000. Reptile hibernacula:
ODPM. 2005. Government Circular: Biodiversity providing a winter refuge. Enact 8(2): 4-7.
and geological conservation statutory English Nature, Peterborough.
obligations and their impact within the planning
system. [ODPM Circular 06/2005; Defra Circular Author and acknowledgments
01/2005]. ODPM. Author Jim Foster. Editor Susie Smith.
Photographs: common lizard, Paul Lacey; all
ODPM. 2005. Planning Policy Statement 9: other photographs, Jim Foster.
Biodiversity and geological conservation. ODPM.
Many people have contributed ideas or data to
OFFER, D, EDWARDS, M & EDGAR, P. 2003. help with this document. Sincere thanks to all
Grazing Heathland: A Guide to Impact who have helped. Particular thanks to everyone
Assessment for Insects and Reptiles. English who provided comments at the Herpetofauna
Nature Research Reports 497. English Nature, Workers Meeting 2010 workshop. Sean Hanna,
Peterborough. Chris Gleed-Owen and John Baker kindly
provided comments on a final draft. Special
PLATENBERG, R J & GRIFFITHS, RA. 1999. thanks to Judy Stroud (Natural England) for
Translocation of slow-worms (Anguis fragilis) as comments and for helping with the workshop.
a mitigation strategy: a case study from south- Some content is based on work done by
east England. Biological Conservation 90: 125- Creswell Associates (Robin Jones and Warren
132. Creswell) for English Nature.
READING, CJ. 1996. Evaluation of Reptile You may reproduce as many individual copies of this
Survey Methodologies. English Nature Research report as you like, provided this is not for commercial
Report No. 200. English Nature, Peterborough. purposes, and such copies stipulate that copyright
remains with Natural England, 1 East Parade,
READING, CJ. 1997. A proposed standard Sheffield, S1 2ET.
method for surveying reptiles on dry lowland Natural England 2011
heath. Journal Applied Ecology 34: 1057-1069.
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Table 7 Minimum standard effort and recommended methods for presence/absence surveys
Reasonable chance of presence Method(s) Minimum standard effort units
Slow-worm ARS 25
Common lizard ARS + DOS 30
Sand lizard DOS# 50
Grass snake ARS + DOS 30
Adder ARS + DOS 30
Smooth snake ARS 50
Key:
* DOS = direct observation survey
ARS = artificial refuge survey
# ARS may be used in addition to DOS if sand lizard expected at high density, and refuges laid at density of at
least 200/ha
For a given site, you should decide which species have/has a reasonable chance of presence. This
decision should be based on considerations such as habitat quality and site location in relation to
known species range.
For each species, look up the monthly weightings, and ideally undertake your survey in the months
with high weightings (4 or preferably 5). Hence for grass snakes, an ideal survey would take place
in May and June.
If this ideal timing is not feasible, then you may undertake the survey during a less suitable period,
but this will mean that more effort is required.
Divide the minimum standard effort units figure (Table 7) by the monthly survey effort weighting
(Table 8) in the months you plan to survey.
This will give you a figure for the number of survey days recommended.
You can then combine the standards for each species into a single site survey standard. In most
cases, visits for different species can overlap.
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Each visit represents one days survey in favourable weather conditions. A days survey must be
sufficient to employ reasonable effort to detect reptiles. As a guide, this should be at least 1 hour for
small (<1ha) sites, to at least 4 hours for medium sized (>5ha) sites. Where weather conditions allow,
two visits per day may be beneficial; these two visits would count as 1 day's effort. For very large or
complex sites, several days may be required to count as a single survey session, or several
fieldworkers can work in parallel.
There must be at least 2 days between each survey visit. If, after calculating the effort required or to
accommodate weather or logistics, this means that the number of survey days will not fit into one
month, they must be spread out over a longer period. If this extends into a month when the survey
effort weighting is higher or lower, the number of visits should be decreased or increased,
respectively. Note that a calendar month is used here as a unit of time only for ease of reference. In
practice, surveys should not be "squeezed" into a particular month where the survey objectives would
be better served by effort distributed over a longer period.
The period between the first and last survey visits must be at least 30 days (this does not mean a
survey on each of 30 days, just that the site was sampled between day 1 and day 30).
Where the minimum standard effort unit divided by the monthly weighting does not result in an
integer (a round number), you should round up, even if the decimal is <0.5. For example, 40 3 =
13.3, indicating 14 visits; 30 4 = 7.5, indicating 8 visits.
A presence/absence survey can cease once the target species is found, and this may occur before
the minimum survey requirement is met. If, however, a population size class assessment is required,
further survey may be needed, at least to the minimum stated in this guidance. This would then
ensure that if a peak count were required, a suitable level of effort would be deployed.
Refuges should only be placed in areas likely to be used by reptiles. When planning surveys, it is
useful to prepare a map of likely suitable habitat so that you can plan where to deploy refuges. The
refuge density figures apply across such habitat.
Where refuges are used for surveys, they must be placed at a density of at least 100/ha of potential
habitat, except where this becomes impractical (for example, on large sites) in which case density
should be as high as is feasible given the site constraints. There should be a minimum of 30 refuges,
whatever the site size.
Where refuges are used, they must be in place for at least 2 weeks of good weather conditions
before the survey starts (this can be in the previous year).
Even where refuges are the prime survey method, surveyors should scan the surrounding habitat as
reptiles may also be found in the open.
Survey timing should be altered to account for prolonged periods of unseasonably hot, cold, wet or
dry weather, all of which may affect reptile detectability.
Where development impacts are high and any of the snake species are expected, it is preferable to
survey in both spring and summer as snakes often use different habitats in these seasons.
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For very small development sites (<0.2ha) and where there is predicted to be only a minor or
temporary impact, survey effort (number of days) may be reduced to half of the recommended value
(but the number of refuges must remain as per the recommendations).
Worked example
Species expected: slow-worm and grass snake. Ideally, survey should occur April to June. This is
most likely to be successful at establishing presence or likely absence. It would also be most cost-
effective for the client since fewer visits are needed.
However, irreconcilable project constraints in this case mean the survey must occur later in season,
between July and September.
July: 3
August: 2
September: 4.
This gives the recommended survey effort per month, as:
An alternative for slow-worm surveys would be to spread the visits out over August and September.
Since August has a lower monthly survey effort weighting (2), proportionately more visits would be
needed. Assume 4 visits are planned for September, that gives a score for September of 4 (visits) x 4
(monthly survey weighting) = 16 standard effort units. For this species we need a total of 25 standard
survey effort units. This leaves 25 16 = 9 standard effort units to be deployed in August. This gives
9 2 (August monthly effort weighting) = 4.5, rounded up to 5 (visits needed in August). Survey
schedule is: 5 visits in August plus 4 visits in September (Option 2).
Grass snake minimum standard survey effort units = 30. Monthly weightings:
July: 3
August: 3
September: 4.
This gives the recommended survey effort per month, as:
July: 30 3 = 10 visits
August: 30 3 = 30 visits
September: 30 4 = 7.5 to 8 visits (rounding up).
Most suitable survey schedule for grass snakes is for 8 visits spread across September. 7 of these
visits can coincide with the 7 visits planned for slow-worm under Option 1 above.
An alternative for grass snake surveys would be to spread the visits out over August and September.
Since August has a lower monthly survey effort weighting (3), proportionately more visits would be
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needed. Assume 4 visits are planned for September, that gives a score for September of 4 (visits) x 4
(monthly survey weighting) = 16 standard effort units. For this species we need a total of 30 standard
survey effort units. This leaves 30 16 = 14 standard effort units to be deployed in August. This gives
14 3 (August monthly effort weighting) = 4.6, rounded up to 5 (visits needed in August). Survey
schedule for grass snakes is: 5 visits in August plus 4 visits in September. This coincides with the
slow-worm schedule.
In summary, the simplest survey schedule for this project would be to undertake 8 visits spread
across September. An alternative would be for 5 visits in August plus 4 visits in September. Because
the August-September surveys would happen during a month where the weighting is sub-optimal
(less than 4), the survey should be spread across a period of around 60 days. Of course, the general
comments mentioned above also apply (surveyor should search for emerging hatchling grass snakes
as survey will cover typical hatching time; pay particular attention to direct observation near ponds;
ensure surveys done during favourable weather conditions; etc).
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Table 9 Deriving a population size class category using survey counts or habitat suitability
assessment
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Table 10 Assessing the broad impact level of a development (Note that these effects are in the
absence of mitigation)
Impact on Typical effects on reptiles and their habitat in Example
population the absence of mitigation (one or more effects)
Negative: Minor disturbance to individual reptiles Repositioning fence posts in horse
negligible Minor loss or damage to broad habitat pasture used occasionally by
reptiles.
Negative: Killing of small proportion of population Constructing a new toilet block on a
low Fragmentation minimally affecting dispersal heathland used by widespread
Moderate damage of broad habitat reptiles.
Introduction of minimal decline factors
Negative: Killing of moderate proportion of population Construction of dual carriageway
medium Fragmentation moderately affecting dispersal road close to edge of site site used
Minor damage to key habitat feature by widespread species.
Moderate loss of broad habitat
Introduction of moderate decline factor
Negative: Killing of high proportion of population Construction of residential
high Fragmentation seriously affecting dispersal development on sand dune system,
Loss of key habitat feature with footprint destroying 80% of
Major loss of broad habitat habitat used by adders and
common lizards.
Introduction of serious decline factor
Notes:
Key habitat feature = feature critical for viability of population, for example, specific foraging area, egg-laying
site, hibernation site
Broad habitat = habitat used for dispersal or general foraging, not critical to population viability
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Table 11 Mitigation strategy options (Note the options are listed in order of preference)
Strategy Outline of methods Relevant development Example of
type; notes on development;
applicability mitigation strategy
Preferred option Timing, location or methods Temporary or very small- Construction of new
Development that could cause harm to scale developments. cycle path in area used
plans modified to species or habitats are Applicable where no for basking & dispersal
prevent harm modified to prevent harm. long-term habitat loss is by slow-worms.
No specific habitat predicted. Do works in winter.
improvements necessary
because no loss incurred.
Small-scale reptile Discourage use of works Temporary or very small- Installation of new
protection: area by substantially scale developments. fenceline in rough
passive measures reducing suitability. No Only applicable where grassland used by
removal or exclusion. No scale of long-term common lizards.
specific habitat habitat loss is negligible, Carefully reduce
improvements necessary and where vegetation vegetation height to
because no loss incurred. and ground conditions ground level for 3m
allow. Not normally either side of fenceline.
applicable for snakes. Remove all refuges.
Small-scale reptile Capture and removal of Temporary or very small- Improving drainage on
protection: active reptiles from works area, scale developments. bank used for
measures often with exclusion to Only applicable where hibernation and basking
prevent re-entry. No specific scale of long-term by adders.
habitat improvements habitat loss is negligible. Install exclusion fence
necessary because no loss around works area,
incurred. capture adders from
works area, place
outside fence, remove
fence on works
completion.
Habitat Capture and exclude Developments which Residential development
improvements, reptiles from works area, result in moderate to resulting in loss of 30%
active reptile relocate them to adjacent high loss of habitat, and of a site used by slow-
protection receptor site, which may or where it is possible to worms.
measures, may not already be used by maintain conservation Improve habitats on
relocation to target species. Restore, status by retaining the receptor site, retain
adjacent area create or enhance habitats population in situ. habitat in greenspace
on receptor site, and/or on Effectively the aim here area in development.
development (if reptiles is to keep a population of Capture slow-worms,
could use it following equivalent status at the relocate to receptor site.
completion of works). same location.
Table continued...
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Working across the table from left to right, the minimum capture effort in days is calculated as:
Species score x (Site size + Population size class/ Habitat Suitability Assessment)
Capture should continue until there has been substantial depletion of the population, ideally so that
all animals have been removed (your attitude toward risk may affect this judgement).
The actual capture period may be substantially longer than the recommended minimum period
recommended here, as capturing reptiles can require huge effort and local circumstances can make
the task more difficult.
To complete a thorough capture period, such that one can have reasonable confidence in having
substantially depleted the population, the minimum number of days derived here should be followed
by 5 days with no reptile captures or observations, under good conditions. Good conditions here
means that the species concerned would be expected to be active, given the weather conditions and
season. This will vary according to local conditions.
Where there are factors that will predictably result in reduced catchability, additional capture effort
should be added to the minimum derived from the calculation here. For example, capture
programmes that start at a sub-optimal time (for example, July); highly complex vegetation;
substantial underground refuge habitat.
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One day = the effort expended by a competent fieldworker in a typical days work. This will often
require several passes of the same area, since reptiles will often retreat into cover and escape
capture when approached. One days effort will often require two visits to the site to coincide with the
best survey conditions; one the in morning and one in the afternoon or evening (depends on species,
season and weather). Capture programmes starting in autumn will often need to be suspended for
winter and re-start in spring.
Adder has a higher species score (25) than the common lizard (20) and so we will use the 25 for
the calculation for minimum recommended capture effort.
Species score x (Site size + Population size class/ Habitat Suitability Assessment)
Rounding up gives minimum capture effort of 28 days. In this case, as the capture programme
cannot start until late June, which is in a suboptimal capture period for adders, the consultant adds
an extra 10 days.
Hence the final minimum capture effort is 38 days. The timing, effort and methods have been
carefully assessed by the consultant and deemed appropriate for the two species at this site. The
actual capture period, of course, may be longer depending on local factors, notably weather
conditions.
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