Lee Brady's Recording Blog

CIEEM Updates Its Position Statement on DLL

Full details are available on the Institute's website. Link here. 

I won't repeat the whole document here, but two items from the statement are worth highlighting.

 

2. There should be a Favourable Conservation Status Strategy for the species. A clear national strategy should be in place for each species setting out what must be achieved to fulfil international and national commitments for the species concerned. Any local or district level licensing (DLL) scheme, strategy, or new approach taken under new licensing policies should clearly demonstrate how it contributes to the delivery of Favourable Conservation Status for the species in its natural range.

 

This really should be a given and it is disappointing that Natural England need to be reminded of the fact. In Kent, one of the arguments that Natural England used to collect data from data providers such as myself was that a delay in providing data may prevent Natural England from publishing a Conservation Strategy for GCN in Kent. Unfortunately once Natural England had obtained data they promptly abandoned their promise to publish the strategy document. After using the data to create their model for the county they also promptly dissolved the data sharing agreement. Unbelievable I know and this has resulted in a complete breakdown in trust. It remains to be seen whether NE will review its position. 

 

3. The mitigation hierarchy should be followed. Strategic licensing schemes should require developers to seek all possible means to avoid impacts on protected species and ameliorate them as far as possible before resorting to compensation via strategic licensing. Strategic licensing should not be seen as a ‘licence to trash’ and, whilst delays associated with translocating each individual could be reduced, proportionate efforts should still be made to rescue and relocate species to safety where possible.

 

One of my particular concerns over the DLL is that it permits the destruction of high quality breeding ponds. I think we all accept that DLL is a development based tool rather than a tool designed to promote conservation. However, NE has taken this approach too far. Not only is it possible for developers to destroy breeding ponds regardless of their importance to local populations, but developers are financially encouraged to do so. Developers that undertake gcn survey work are penalised by having to pay more for their DLL licence than developers that do no survey work. So not only does DLL facilitate the destruction of important breeding ponds, but it does so in a manner that actively reduces the likelihood that data will be collected to demonstrate the impacts.  How can the mitigation hierarchy be followed if survey work to collect baseline data is not undertaken? 

 

Woking Consultation Document - (3) Favourable Conservation Status

In the Q&A section of the Woking consultation document, one of the questions is (pg. 11):

 

"Does the proposed scheme risk contravening the legislation which protects GCN?"

 

The answer is as follows:

 

"As with any other protected species application, before an organisational licence is issued, the proposals will be assessed against the three legal tests required under in the Conservation of Habitats and Species Regulations 2010 (as amended) (the “Habs Regs”), namely:

• 􏰀  Purpose (in this case: imperative reasons of overriding public interest including those of a social or economic nature and beneficial consequences of primary importance for the environment);

• 􏰀  That there is no satisfactory alternative;

• 􏰀  That the action authorised will not be detrimental to the maintenance of the species concerned at a favourable conservation status in their natural range. 

Under the Habs Regs, Natural England is the competent licensing authority and will ensure that the three licensing tests are assessed objectively."

 

Emphasis mine. 

The consultation document defines FCS (pg. 14):

 

"a situation where a habitat type or species is doing sufficiently well in terms of quality and quantity and has good prospects of continuing to do so in future."

 

The current system of gcn licensing requires consultant ecologists to prepare a method statement that incorporates actions designed to ensure that the FCS test is met. NE review licence applications. If they are not satisfied that FCS will be met, the licence is rejected. The Woking pilot will require NE to grant Woking BC an organisational licence to implement the scheme. 

You can therefore imagine my surprise when I read on pg. 30 of the Woking consultation document:

 

"This strategy does not seek to define a Favourable Conservation Status or Favourable Reference Values for GCN in the Borough..."

 

If the proposed strategy does not seek to define FCS for gcn in Woking, then how will the third test be met? Or have I missed something? 

 

Further Thoughts on Woking - (2) Distribution Modelling & Sample Sizes

Here's where we start to get to the nitty gritty of the Woking Pilot project. How many ponds were actually sampled to inform the distribution modelling? Was it enough to support the conclusions made in the consultation document?

The document published by Woking BC is intended to be read and understood by local residents and is therefore not scientific in its nature. And I certainly don't have a problem with that. Creating documents that are accessible to as many interested parties as possible should be encouraged. An attempt has been made to include Annexes that provide more detail and these include useful summary points. The problem with summaries though is that they can be misleading. The conclusions drawn may not be justified by available evidence. Without access to all data it may simply not be possible to undertake a detailed review. I won't let that stop me trying though. 

Data on gcn distribution in Woking appears to have been collated from information held by Surrey Amphibian and Reptile Group, Surrey Wildlife Trust and directly sourced from an eDNA and HSI study funded by the pilot project. Let's dig a little and pull out some numbers. 

 

Total number of ponds in Woking - not specified

Number of ponds assessed for HSI = 100 (pg. 20)

Number of ponds assessed for eDNA = (50 stated on pg. 20; 48 stated on pg. 33)

Number of ponds assessed for both HSI & eDNA = 36 (pg. 33)

Number of ponds with positive eDNA results = 5 (pg. 33)

Number of additional ponds with verified gcn records = 8 (pg. 33)

 

These are very (very!) small sample sizes. We don't even know what proportion of the available ponds they represent. I'm also confused as to why HSI assessments were not taken for all of the ponds sampled for eDNA (only 36 out of 50/48)?

There's also no confirmation that the HSI and eDNA data was collected following all appropriate guidelines. NE have quite rigorous requirements for eDNA sample collection. Were these guidelines actually followed? 

The author(s) have attempted to correlate the results of the 36 ponds assessed for both HSI and eDNA with landscape level habitat variables derived from Land Cover Map 2000 (pg. 33):

 

"The results showed a positive correlation with the extent of urban areas within 250m (or a negative correlation with distance from urban areas) and a negative correlation with the extent of arable land. This suggests that urban areas may provide a greater diversity of habitats required by GCNs than arable areas. They also showed a weak negative correlation with the extent of woodland and conversely with distance to heathland."

 

That's quite a bold statement for a study based on just 36 ponds, only 5 of which were found to be occupied by gcn (assuming these 5 were all in the group for which HSI data was collected). 

My own work investigating the relationship between gcn and landscape habitat variables does not support these conclusions. In Kent, gcn are negatively associated with urban areas and appear somewhat neutral with respect to woodland. The Kent dataset is based on a sample of several hundreds of occupied ponds across the whole county. Since the Woking project did not assess ponds across the whole of Surrey, the relationship between gcn presence and landscape habitat variables is highly biased since it is significantly influenced by the extent of each habitat category present in the borough. Looking at the Woking BC map, it appears that much of the borough is dominated by an urban landscape. 

 

 

Results have been used to identify three metapopulations (Fig. 1, above) and these are described as follows:

 

Littleneck - 'a small number of ponds' .. 'largely in good condition'

Hook Heath  - 'only one or two ponds'

Westfield - 'a larger number of ponds' ... 'in poorer condition'

 

These descriptions really are a bit woolly! Are these occupied ponds or all ponds? What does 'a small number of ponds' mean? Three ponds? Four ponds? At Hook Heath there were 'one or two ponds'. Which was it? Surely the authors know?! What does 'larger number of ponds' mean? Five or twenty five? Come on this wouldn't be acceptable for an undergraduate project, let alone a project attempting to define the conservation of gcn in a whole borough for the next 25 years!  

 

 

In Woking, the metapopulaton with the highest number of occupied ponds can be inferred by reviewing the zones identified in Fig. 2 (pg. 23 of the report, shown above). Westfield, located to the south, appears to have the most occupied ponds and also happens to be the most rural. You'll also notice that few (if any) of the populations occur wholly within urban areas. 

Although the apparent quality of individual gcn occupied ponds may well be better in locations situated closer to urban areas (especially when subject to positive management work), such ponds can be at greater risk from direct disturbance, introduction of fish and increased fragmentation of surrounding terrestrial habitat. 

The interaction between gcn pond occupancy, pond quality and urbanisation has not been fully investigated within the report and such work is important if we are to more fully understand the Future Prospects of gcn in Woking. For example, if we assume a similar number of ponds in each of the three metapopulations, why was occupancy so low in two of the areas? Could it have been that the overall number of suitable ponds is lower in more urban areas? The HSI assessment does not appear to consider the quality of unoccupied ponds in each of the three metapopulations.

In fact I'll go a step further and propose a different interpretation of the data than that presented in the consultation document. Look again at Fig. 2 on pg. 23. The apparent relationship between gcn occupied ponds and urban areas has nothing to do with the alleged greater range of habitats that these areas may provide. Newts aren't colonising ponds on the edge of urban areas from the surrounding countryside. Urban areas in Woking are expanding and encroaching on existing newt habitat. Previously occupied ponds located within urban areas have been lost. Once urban areas expand to envelop the few gcn ponds that remain they will also be lost. If anything, the study presented here is an indictment of development and could be used to argue that in order to achieve a Favourable Conservation Status for gcn, there should be no more development projects in Woking! I'm fairly sure that's not what the council intended when they published the report for all to read. But I digress... 

 

The results for Maxent modelling reveal the importance of larger sample sizes.

 

"Validating the results against the eDNA results, i.e. the 5 positive records used for training with the 43 negative results suggests that the model is providing a good fit to the training data and absence data GCN results."

 

Remember, the pilot project was using just 5 positive records to inform a distribution model for the whole borough. Is it really a surprise that using the same training data that was used to develop the model produced a good fit? What happens when independent data is tested? 

 

"The SARG records contain eight validated records with 1m grid references within the Woking boundary. Testing these against the Maxent model trained with the eDNA positive records produces a poor fit."

 

Which contradicts an earlier statement made in one of the summaries (pg. 20):

 

"There is a strong coincidence between the predictions from the modelling and the field records"

 

The authors do appear to have subsequently incorporated the SARG records into a Maxent model: 

 

"Training and testing the model using the available positive field records and the negative eDNA records shows an improved fit to the training data combined with the absence data."

 

It's quite revealing that the author(s) do not claim there to be a good fit using the SARG records, only an improved fit. An improvement on poor may well still be poor. Either way, it's something of a stretch to suggest a strong coincidence. 

 

In conclusion, I believe that the sample sizes used in this pilot project are simply too small. A far more rigorous survey programme is required. The fact that there are (pg. 20):

 

"sparse, sporadic records elsewhere in the Borough."

 

Suggests to me that even in a limited areas such as Woking, sampling effort hasn't been sufficiently high to reliably identify all possible metapopulations. In a blog article such as this, I'm loathe to start referencing too much published research. However, there is one conclusion from a 2008 study on the performance of distribution models that I will quote:

 

"No algorithm predicted consistently well with small sample size (n < 30) and this should encourage highly conservative use of predictions based on small sample size and restrict their use to exploratory modelling."

 

M. S. Wisz, R. J. Hijmans, J. Li, A. T. Peterson, C. H. Graham, A. Guisan and NCEAS Predicting Species Distributions Working Group (2008) Effects of sample size on the performance of species distribution models. Diversity and Distributions, (Diversity Distrib.) (2008) 14, 763–773

 

Some Thoughts on the 'Woking Project' - (1) Costs

Reviewing a large project such as this, particular one that attempts to encompass so many different issues is no small challenge. But I've now read the consultation documents and made some conclusions. 

The short version is this. Developing a strategic approach to dealing with planning matters and protected species such as great crested newts will be a huge boon to large developers. If done to a scientifically high standard in a manner that addresses Favourable Conservation Status it could also benefit newts.

However, I think the current pilot project may not be quite so attractive to developers working on smaller schemes that would have a low impact on gcn populations. I'm also not fully convinced by the scientific evidence presented in the report and it is clear that no attempt has been made to address the thorny issue of what great crested newt Favourable Conservation Status means in Woking. 

Since writing about this project will require a lot of words, I think I'll break my thoughts down into digestible chunks and publish these over the course of the next few days (time permitting). And yes, I've deliberately left this to the last minute because I prefer that if folks want to comment on the proposals themselves, they do so without being influenced by me. 

I'll start by looking at the projected costs to developers. 

Developers who sign up to the scheme no longer need to be concerned by undertaking newt survey work in good time. They won't need to worry about planning conditions that state newt survey and/or mitigation work is required. Nor will they need to be concerned by leaving everything to the last minute. Nope, those concerns will be gone. Pay up and build. Unless of course there are other protected species present on the site. In which case (at least until Woking BC draw up provision for including bats, dormouse, reptiles etc), this is all moot since development will still be delayed.

If capture work for slow-worms is undertaken on a site supporting newts, then it is quite possible that newts will be encountered. According to the proposals, under these circumstances somebody still has to move any newts that are encountered. Who? Where will the newts be moved to? What disease control measures will be undertaken? Has Woking heard of Chytrid? What additional costs will this all incur?

There is also an odd payment matrix (detailed on pg. 9 of the consultation document). Apparently it will cost £900 (per development) to participate in the scheme. That sounds relatively inexpensive. But there is also a multiplier that depends on which area of Woking the development occurs in. Areas considered most important for newts have a x3 multiplier associated with them (the 'orange zone'). There is also a multiplier that comes into affect based on the number of ponds located within 500m. Large development projects (e.g.  20+ residential units) in the 'orange zone' that destroy 3 ponds on a site with very high quality terrestrial habitat would therefore be asked to pay £900 x (3 x 3) = £8,100 (+undefined council legal fees). This would be considered very inexpensive for a large development project and would be more than paid for by virtue of the savings made through removal of delays. Yet this price does not really take into consideration the true impact of the development. Rather bizarrely, the report author(s) claims (pg. 28) that

'the value of terrestrial habitat is not correlated with area'

This statement alone makes me highly concerned about the credibility of the author(s) and is certainly at odds with current licensing. Worst still, a small developer building three houses at a distance of 450m from the same three ponds on land displaying low quality terrestrial habitat would have to pay the exact same fee! Such a developer may not have to pay anything for newt mitigation under the existing licensing system. 

The pricing matrix has clearly been designed to favour large developers but in my opinion it is broken and needs a radical rethink. 

Stay tuned for more thoughts... 

 

Great Crested Newts Found at Horish Woods

“With the habitat split by the M20 and rail link, combined with motorway run off which drains into the only pond on site, means that it’s been a surprise to find so many living here.

“In fact, this area has been the most prolific site we have ever had for newts which is a huge shock.”

via www.kentonline.co.uk

Actually this is not such a surprise. Isolated sites often display higher than expected populations of newts. Juveniles have nowhere else to disperse to so local densities can be higher than would normally be anticipated. Detectability issues in finding adult newts at breeding ponds also needs to be carefully considered (example). Low counts of adult newts in a murky pond, do not necessarily mean that the population size is small. 

 

  

More Musings on Receptor Site Location - How Far is Too Far? Part 1

There are advantages and disadvantages to translocating reptiles to sites that are located nearby and sites that are more distantly located.

In attempting to recommend appropriate translocation distances I will take a closer look at the previously identified negative factors that may influence the location of a proposed receptor site. Since this is likely to be rather a long blog post I will split the article into two sections. This is Part 1. Part 2 will follow in due course.

 

Availability of Receptor Sites

The more land area that is available for review, the greater the choice of suitable receptor sites that are likely to be found. If distance restrictions are too severe the availability of high quality receptor sites may be compromised.

 

Homing Behaviour

Some reptile species have well defined home ranges. Detailed studies on the home range size of lizards are rather limited, but available information suggests that most are relatively small and can probably be defined by low hundreds of square meters (Beebee and Griffiths, 2000). Dispersing individuals (especially juveniles) may move over greater distances. Species that may appear to be rather sedentary (e.g. slow-worm) may actually display seasonally influenced movement patterns (e.g. Riddell, 2000), although the extent of such movements are likely to be site specific. Viviparous lizards can attempt to vacate adjacent receptor areas and return to their place of capture, even climbing over so-called reptile exclusion fencing in the process (pers. obs). Similar behaviour has been observed in grass snakes (pers. obs.) and adder (Whiting and Booth, 2012).

British snakes have larger home ranges than lizards. Some published studies have suggested that grass snakes can move over large areas with home ranges calculated as several hectares (e.g. Madsen, 1983). Like slow-worms, movement of grass snakes can be influenced by season (e.g. Reading and Jofre, 2009). Female grass snakes lay eggs and may display extensive movements before and after oviposition (Madsen, 1983). Adder also display seasonal movements, with snakes moving between winter hibernacula and summer foraging sites (e.g. Presett, 1971; Andersson, 2003). Such movements may occur across a kilometre or more, even through apparently unsuitable habitat (e.g. through mature woodland).

Human-wildlife conflicts following development may be an important consideration if species such as adder are translocated into nearby areas. In these situations, consideration must be given to ensuring that such conflicts are minimised (e.g. through installation of permanent exclusion fences and appropriate habitat management work). In some cases it may be necessary to translocate adder to sites that are located sufficiently far away to prevent homing so as to minimise potential risks to both people and snakes. Such situations may arise during the construction of housing developments, schools, hospitals etc. Although the actual risk of a person being bitten by a translocated adder is probably very low, the perceived risk may be considered much higher by the public. When stories about snakes and children hit the press, significant negative publicity that undermines conservation actions can result. These issues need to be carefully considered.   

Increased dispersal has been found to be a significant factor affecting the welfare of translocated animals (Harrington et. al. 2013). If animals disperse away from a remote receptor site to such an extent that they experience increased mortality or are unable to form a viable breeding population, the translocation should be considered a failure - even if the work meets statutory requirements in preventing animals being killed during development. Problems associated with dispersal and homing behaviour can be minimised through the installation of fencing that restricts animals to previously prepared habitat areas (e.g. Whiting and Booth, 2012). Translocation of reptiles (especially snakes) to more distant receptor sites should be accompanied by increased monitoring effort and this will be discussed in a future blog post.

 

Loss of Local Biodiversity Interest

The loss of 'local' biodiversity interest may mean different things to different people. A site manager may consider the movement of animals out of her reserve to be a local loss. If the animals are moved into a different local authority area, the planning officer may consider it to be a local loss. Recorders may be concerned about animals being moved between recording areas etc.

The key thing here is to define what we mean by local.

The Oxford Dictionary defines local as:

 

1. relating or restricted to a particular area or one’s neighbourhood...

2. (in technical use) relating to a particular region or part, or to each of any number of these...

 

In effect then, local has no fixed spatial definition and can mean almost anything provided it is described in the context of neighbourhood or region.

At the risk of sticking my head above the parapet, I will propose a definition that is appropriate in conservation terms for UK reptiles:

 

Local relates to a predefined area of land that is situated within a specified landscape area within a recognised vice county.

i.e. A receptor site is local to a development site because they are both situated in the same character area and the same vice county.

 

Definitions for character area are dependent upon country. In England, national character areas have been developed by Natural England and appear to replace the previous natural areas, but as far as I can tell use the same boundaries and definitions. Countryside Council for Wales has published a Landscape Character Map (pdf download) and Scottish National Heritage has produced a Landscape Character Assessment. In Northern Ireland, Environment and Heritage Service has published Landscape Character Areas (pdf download).

Vice counties have fixed boundaries that are not influenced by changing political boundaries.

Note that my proposed definition is not limited by distance. Providing the criteria are met, a local site could actually be situated several kilometres away. This may not necessarily be a good thing and other factors are likely to come into play. 

 

Inappropriate Mixing of Genes

I have already discussed the issue of subspecies and race, at least in the context of sand lizard. However, defining the maximum distance that translocations of more widespread species is problematic. Not only are the animals by definition more widely distributed but available research is very limited.

Following publication of a Natural England report highlighting the national decline of adder (Baker et. al. 2004), several projects have been announced that attempt to review the conservation impacts of restricted gene flow. One such project has been organised by Zoological Society of London (ZSL) another by University of Sunderland. However, rather than discouraging translocations these projects may actually collect data that supports the earlier work of Madsen (1999), who found that an inbred population could be restored (at least temporarily) by introduction of a single male adder. Moving animals may actually benefit isolated populations by introducing new genes and therefore increasing reproductive fitness.

After reviewing distribution data for adder in Kent, I believe that genetically distinct populations may be found in different areas (i.e. North Downs and High Weald). Whilst no research is currently planned that will investigate such claims, the movement of animals between different landscape areas could jeopardise future research projects. If the movement of animals follows the previous definition of local, such problems can be minimised. Limiting translocations to local receptor sites should not increase the risk of inbreeding depression.

 

Differences in Habitat/Geology

Some species have very specific habitat requirements. These may be quite obvious for rare reptiles such as sand lizard, but widespread species can display their own preferences. At least one study in North America has shown that a reptile's prior experience can be an important factor in determining translocation success (Roe et. al., 2010). Slow-worm are sub-fossorial lizards that are frequently encountered in proposed development sites. Animals that have become accustomed to sites with disturbed ground (e.g. old allotments) may have difficulty in establishing populations in receptor sites characterised by different ground conditions (e.g. chalk grassland). The greater the distance that animals are translocated, the more likely it is that receptor sites will be characterised by a different geology. Chalk woodland and clay woodland habitats are very different. Adder favours one, but Kent populations are almost completely absent from the other.

Problems associated with habitat and geology can be minimised if receptor sites are kept local.

 

Displacement of Individuals from Home Range

Work with some snake species has shown that translocated animals display greater individual movements than undisturbed individuals (e.g. Roe et. al., 2010). These increased movements can result in higher mortality (e.g. through increased predation, movement into unsuitable habitat or roadkill). A large-scale translocation project described by Kyek et. al. (2007) ensured that animals were able to move from receptor areas through suitable habitat corridors back to enhanced habitat areas around the completed development. Although individual movement during this project may still have been high, released reptiles were less likely to disperse into unsuitable habitat.

Whilst the number of UK projects that publish post translocation monitoring results are limited, available reports tend to suggest relatively low numbers of observations of released animals. Whilst some of these results may be due to sample effort (e.g. Lyle, 2008) other reports have suggested low detectability in a high quality but complex habitat (e.g. Cresswell et. al., 2012). It is possible that low encounter rates of post translocation snakes are caused by dispersal of animals away from release areas. At sites where the species has not previously been recorded, such dispersal could result in failure of the translocation project due to animals dispersing away from each other across a large area. In these situations the apparent health of individual animals may remain high, but breeding success becomes less successful over time. Whether observed patterns of apparent population expansion are simply due to individual dispersal away from release areas or a genuine increase in population size remains unclear.

On one hand translocating reptiles to sites within or close to their existing home range may increase homing behaviour that results in conflicts with the residents of new developments (and their pets!). On the other, releasing animals at receptor sites located outside of their home range may increase the risk of translocation failure. It is important to consider that a local site may still be located beyond the home range of a translocated animals.   

 

 

I warned you it was going to be a long post!

Part 2 will address issues relating to stress, disease and potential impacts on other species.

 

References

Andeersson, S. (2003) Hibernation, habitat and seasonal activity in the adder, Vipera berus, north of the Arctic Circle in Sweden. Amphibia-Reptilia, 24, 449-457.

Baker, J., Suckling, J. and Carey, R. (2004) Status of the adder Vipera berus and slow-worm Anguis fragilis in England. Natural England.

Harrington, L. A., Möhrenschlager, A., Gelling, M., Atkinsone, R. P., Hughes, J. and Macdonald, D.W. (2013) Conflicting and complementary ethics of animal welfare considerations in reintroductions. Conservation Biology, 27, 486-500.

Madsen, T. (1983) Movements, Home Range Size and Habitat Use of Radio-Tracked Grass Snakes (Natrix natrix) in Southern Sweden. Copeia, 1984, 3, 707-713.

Madsen, T. (1999) Restoration of an inbred adder population. Nature, 402, 34-35.

Presett, I. (1971) AN ecological study of the viper Vipera berus in southern Britain. Journal of Zoology, 164, 373-418.

Reading, C. and Jofre, G.M. (2009) Habitat selection and range size if grass snakes Natrix matrix in an agricultural landscape in southern England. Amphibian-Reptilia, 30, 379-388.

Riddell, A. (2000) The special ecology and ranging behaviour of the slow worm Anguis fragilis. MSc thesis, University of Kent.

Roe, J.H., Frank, M.R., Gibson, S.E., Attum, O. and Kingsbury, B.A (2010) No place like home: an experimental comparison of reintroduction strategies using snakes. Journal of Applied Ecology, 47, 1253-1261.

Whiting, C. and Booth, H. J. (2012) Adder Vipera berus hibernacula construction as part of a mitigation scheme, Norfolk England. Conservation Evidence, 9, 9-16.

Reptile Receptor Sites - Location

There seems to be a general consensus that reptiles should be either retained on site or moved into an adjacent area of land. Translocation of reptiles to more distant receptor sites is considered to be a 'last resort' strategy.

Examples of published documents that attempt to provide guidelines for UK reptile translocations have been produced by Herpetofauna Groups of Britain and Ireland (HGBI, 1998), JNCC (Clemons and Langton, 1998), English Nature (Moulten and Corbett, 1999, English Nature, 2004) and Highways Agency (2005). 

All organisations emphasise the importance of in situ mitigation within the development site itself. Avoiding impacts is clearly the best outcome for reptiles and can be the cheapest option for developers (particularly when delays caused by capture and relocation work are considered). Of course it isn't always possible for new developments to avoid disturbance. Whilst some form of on site relocation may be possible, things get more difficult when ex situ receptor sites are required. Although Clemons and Langton (1998) make no recommendations over distance, both HGBI (1998) and Highways Agency (2005) recommend that receptor sites should be 'close' to the development. Natural England (2004) seem to accept that receptor sites can be:

 

some distance away

 

Translocation of slow-worms from a Canterbury development attempted to follow the HGBI (1998) guidelines and involved the movement of animals to a receptor site located within 1 km (Platenberg and Griffiths, 1999). Can 1 km be considered close? HGBI (1998) attempt to define the distances acceptable for translocations:

 

at least within the same county or similar administrative area, and the same geology and habitat type

 

In this context 1 km is very close indeed. But clearly the HGBI (1998) definition is rather broad. What is meant by 'county'? Administrative county? Vice county? What about unitary authorities? 'Kent' includes areas that are governed by Kent County Council. However, the Hoo Peninsula is part of Medway Unitary Authority. Is it wrong to translocate reptiles between Kent and Medway? Since Kent is a large county it includes two vice counties; East Kent (VC15) and West Kent (VC16). Is it acceptable to move animals between vice counties? Both Sheerness and Faversham are located within the same local authority area (Swale). However, Sheerness is situated on the Isle of Sheppy. Is is acceptable to move animals between mainland and island sites, even if they are situated within lthe same local authority?

As a recorder I would prefer that reptiles are relocated to areas within the same recording unit. This would help to ensure that the status of populations are maintained in a manner that does not confound future monitoring work. Recording units could be represented by 1 km squares, 10 km squares or vice counties. However, as I will discuss in a future blog post even this obstacle can be overcome (at least to some extent), providing the donor population and receptor site are clearly recorded and results are made publicly accessible.

Of course reptiles do not recognise such artificial boundaries. Although HGBI (1998) imply that it is acceptable to translocate a population several tens of kilometres from one side of a county to another - what about animals occupying development sites that are situated on the boundary? Would it perhaps be better to relocate these animals to a site that is closer, but located in a different county? Restricting the movement of animals to locations within an administrative area may impose unnecessary constraints on a mitigation project that do not contribute to meaningful conservation outcomes.

In a study that investigated the feasibility of introducing grass snakes into the London Wetland Centre, McGrath (2004) acknowledged that introduced animals should originate from a site that is located:

 

in the same geographic region

 

McGrath interpreted this as a site located in:

 

London and otherwise the south-east of England.

 

That's quite a large area. McGrath subsequently suggested that since only one sub-species of grass snake is native to Britain:

 

populations from Britain as a whole could be accepted

 

McGrath seems to be suggesting that the limit on translocation distance should be defined by genetics. However, I wonder if defining genetic variability by sub species is perhaps too simplistic. The movement of sand lizards between Merseyside and Dorset would I suspect be rather frowned upon, even though the animals are the same (sub) species. In their Sand Lizard Conservation Handbook, Moulton and Corbett (1999) consider translocation and advise:

 

The animals used should be of the right genetic type for the area. The three different regions ie. Merseyside, Weald and north Surrey and Dorset support populations that appear to be different and these may represent distinct “races”. Therefore any re-introductions must avoid mixing (or the possibility of mixing) of these “races” and where possible should use the stock most appropriate for the site.

 

Perhaps distinct genetic races are less likely to be prevalent in species such as grass snake that are widely distributed across England and Wales. Grass snakes subsequently introduced to London Wetland Centre originated from Holborough in Kent (Anon 2011) - a site located 50 km away. Other long distance translocations have also been publicised in the media. One such project involved the translocation of several thousand reptiles (multiple species, including adder) from Essex to Wiltshire; a distance of over 150 km. In an attempt to promote good practice, Cresswell et al describe mitigation work involving viviparous lizard and adder along the A74 trunk road near the Scottish Border:

 

Best practice in this regard dictates that, wherever possible, reptiles should be relocated to locations adjacent to or in the immediate vicinity of their existing home ranges or population centres. Only as a ‘last resort’ should they be moved.

 

Difficulties in identifying suitable adjacent habitat meant that adder:

 

would need to be translocated to a suitable ‘receptor site’ some distance from the scheme

 

The distance to this receptor site is not disclosed.

Since translocation projects have been undertaken that involve the movement of reptiles over large distances, is there still a need for guidelines to recommend local receptor sites? In attempting to answer this question I've reviewed available literature to identify relevant issues. These are listed as positive (+) and negative (-) factors:

 

Short Distance Translocations

+ Species populations are maintained in the local area.

+ Species with large home ranges are less likely to be displaced.

+ Lower captivity and transport times will help to minimise stress and thus reduce post release mortality.

+ Risk of disease transmission between populations minimised.

- Receptor sites may be unavailable.

- Even if available, there is likely to be less choice possibly resulting in selection of sites that are of a lower quality.

- Homing behaviour of some species could result in animals moving back into areas inappropriately.

 

Long Distance Translocations

+ Greater choice of high quality receptor sites.

+ Translocations can benefit conservation through targeted (re)introductions.

+ Species with homing behaviour less likely to return.

- Loss of local biodiversity interest.

- Increased risk of inappropriate mixing of unique genetic races.

- Movement of animals into areas with different habitat/geology that may increase dispersal and mortality.

- Increased risk of moving species out of their natural range (even if habitat/geology appears the same).

- Movement of individuals out of their home range may increase risk of homing and dispersal, causing increased mortality through predation, road kill etc.

- Increased stress through longer captivity and greater travel distances.

- Increased risk of disease transmission to new areas.

- Possible unforeseen impacts on species already present at receptor site.

 

Available information suggests that whilst there may some tradeoffs in choosing local receptor sites, translocating animals over long distances introduces many variables that significantly increase the risk of the translocation failing. The next question is how far is too far?

 

References

Anon (2011) Reptiles and Development. MKA Ecology.

Clemons, J. and Langton, T (1998) Species translocation. In Herpetofauna Workers Manual, Joint Nature Conservation Committee.

Cresswell, W., Hay, J., Whitworth, R., Head, M. and Penniston, L (2012) Moving lizards and snakes from the path of new roads and improvements: how to get it right. Creswell Associates.

Herpetofauna Groups of Britain and Ireland (1998) Evaluating Local Mitigation/Translocation Programmes: Maintaining Best Practice and Lawful Standards. HGBI Advisory Notes for Amphibian and Reptile Groups.

Highways Agency, (2005) Design Manual for Roads and Bridges Volume 10 Section 4, Part 7, HA 116/05 Nature Conservation Advice in Relation to Reptile and Roads, HMSO, London.

McGrath, A. (2004) Introduction of Grass Snakes to the London Wetland Centre: A Feasibility Study. MSc Thesis. Imperial College London.

Moulton, N. and Corbett, K. (1999) The Sand Lizard Conservation Handbook. English Nature.

Platenber, R.J. and Griffiths, R.A (1999) Translocation of slow-worms (Anguis fragilis) as a mitigation strategy: a case study from south-east England. Biological Conservation, 90, 125 - 132.

 

'Licence to trash'

...this BO is the nose wrinkling acronym for biodiversity offsetting - a concept that has been criticised by some environmentalists as a licence to "trash" the countryside.

via www.bbc.co.uk

'Licence to trash' & 'BO'?

Biodiversity offsetting is certainly encouraging journalists to use some rather descriptive terms.

It looks like the current scheme is going back to the drawing board and won't be on public display until much later in the year. Perhaps the concerns of conservation organisations have actually been listened to? 

Hopefully there is still time for the powers that be to get revised herpetofauna mitigation guidelines properly drafted. 

 

Reptile Receptor Sites - Selection Criteria

In 2005 Natural England (then called English Nature) published a document that offers advice to developers on issues related to reptile survey and mitigation work. The document is still available and includes useful information, including a summary of the critical factors that should be taken into account when selecting a receptor site:

 

"You should take into account a number of factors when selecting sites, including agreement from the landowner and local interest groups, site safeguard, assurance of long-term favourable management, and access for monitoring. Locating a suitable release site can take many weeks of survey effort, fact-finding and liaison. If no suitable site can be found, then it is possible that the development will be prevented from proceeding in its original form. "

 

By referencing this booklet, together with books, published papers and various reports, it is possible to propose reptile receptor site selection criteria. Some of these factors will be further discussed in future blog posts. I will then use these criteria to propose a simple scoring system that allows different proposed receptor sites to be compared.

 

1. Location

Ideally, reptiles should be retained on site or released into an adjacent area of land. When ex situ mitigation exercises are being considered, the location of a proposed receptor site is often influenced by many different factors that may result in animals being moved over much greater distances and this will be discussed in a future blog post.

 

2. Area

The proposed receptor site should comprise an area that is at least as large as the area of reptile habitat that will be lost to development. If the proposed receptor site is smaller, available (including enhanced) habitat must be of a sufficiently high quality to support the animals being translocated. Ideally, receptor sites should be both larger and include proposals to enhance existing habitat.

 

3. Existing Habitat

Receptor sites must include habitat that is suitable for foraging, sheltering and protection. Proposed receptor sites that consist of unsuitable habitat are likely to require significant enhancement work before reptile translocation is possible. Habitat enhancement work on such sites can involve considerable effort and it may take several years before the vegetation sward is sufficiently well established to support translocated reptiles. Determining the suitability of habitat for reptiles includes consideration of many different factors and these will be explored in a future blog post.

 

4. Extant Reptile Population

The proposed receptor site should not support a population of the species to be relocated, but must be capable of supporting such species with appropriate habitat enhancement works. Additional survey work may be required at the proposed receptor site to determine likely presence of species. This is important to ensure that the mitigation works do not result in a net loss of reptile populations. Although it may be possible to translocate small numbers of animals into an existing population, it is important to ensure that a site's carrying capacity is not exceeded. It is also possible that concerns over disease transmission may make such additions to existing populations undesirable.

 

5. Predators

Reptiles are preyed upon by a wide range of different predators. In some situations the local abundance of a predator could reduce the likelihood of translocated animals establishing a successful population. Species that may be particularly problematic will be discussed in a future blog article.

 

6. Site Safeguards

The proposed receptor site should not be subject to planning or other threats (including unsympathetic management work) for the foreseeable future).

 

7. Site Management

The proposed receptor site should be subject to a written, agreed and funded management agreement. The management agreement should include reference to any additional works that are considered necessary to help establish translocated animals.

 

8. Site Monitoring

The proposed receptor site should be subject to a written, agreed and funded monitoring programme. The time required for monitoring and the extent of monitoring works required are likely to be determined by the size of the reptile population and impacts of disturbance. Proposed objectives will be discussed in a future post.

 

^{[update 1/8/2013] Added predators as an additional selection criteria to consider (ref. Gemma Harding 2004. British Reptile Translocations Guidelines for the selection of receptor sites). Some other factors that folks have suggested can be included within criteria 4 - Existing Habitat (e.g. topography, vegetation, temperature, connectivity etc).}

Biodiversity Off-setting

Biodiversity off-setting was announced in the Government’s Natural Environment White Paper - its 50-year vision for the natural environment. It is an approach that can be used to compensate for habitats and species lost to development in one area, with the creation, enhancement or restoration of habitat in another.

The idea is that any residual negative impacts on the natural environment would be compensated for, or ‘offset’ by developers. We believe that the offsets should be used near the impact, targeted locally in strategic areas that will benefit wildlife, for example to create ecological networks.

via www.wildlifetrusts.org

 

Biodiversity off-setting  includes habitat compensation in situations where mitigation cannot be undertaken. I'm not sure how this can be squared with the legal protection of certain species (and habitats), particularly those covered under the Habitat Regs.  Off-setting is therefore likely to include other mitigation actions such as reptile translocation.

Presumably The Wildlife Trusts believe that sites purchased by developers to compensate for the loss of habitat through development should themselves be free of future development risk? Unfortunately recent proposals by Wiltshire Wildlife Trust don't exactly inspire confidence. 

In their 3 point plan, The Wildlife Trusts recommend the following:

 

1. The starting point for any development proposal should be to avoid damage to our most important wildlife sites.
2. Next, it is essential to mitigate the potential damage of a development through good design.
3. Only then - and as a final measure - should off-setting be considered to compensate for damage that cannot be avoided or mitigated. 

I don't disagree with any of these points, but what about ensuring the site proposed for off-setting is protected against inappropriate future development. Perhaps that needs to be added? Does the site selected for biodiversity off-setting need to meet minimum requirements before it is selected? What happens if another protected site is selected, or an unprotected site with high biodiversity interest? Is that really offsetting? When off-setting includes translocation (restocking), IUCN guidelines need to be considered. 

In an article in today's Express, problems with the hasty implementation of biodiversity off-setting are highlighted.

 

However, the Wildlife and Countryside Link, an umbrella organisation for conservation groups – with a combined membership eight million – has written to Environment Secretary Owen Paterson outlining their “extreme concerns” that offsetting is being rushed through.

 

Organisations that see the prospect of biodiversity off-setting as a quick way to acquire land, need to carefully consider how the public will react to their involvement. As Wiltshire Wildlife Trust have demonstrated all too clearly, misjudging the public mood can result in very negative PR. Conservation organisations simply cannot afford to lose public trust...