Which tree survey do I need ?

Sycamore canopy in spring bud

Clients are often asked by planners or others for a tree survey, but are not always sure what type is needed.   We have outlined the different types of tree surveys and the reasons they are needed.

A. Development survey = BS5837:2012 ‘Trees in relation to design, demolition and construction- Recommendations’

A Development Survey also called BS5837 survey is the one normally required by Local Planning Authorities (LPA) for development and planning permission.

A competent “arboriculturalist” [ = tree person ] must inspect the trees on and adjacent to the site. The trees on site are assessed in terms of their retention value which includes their health, longevity and amenity impact.

Trees that are marked for retention, as well as any adjacent trees not on site but affected by development need to be protected from any potential harm that may occur during the demolition and construction phases of the project. This involves both above and below ground precautions. Above ground, the crown spread and dimensions of the tree will need protecting, below ground the roots of the tree are a constraint governed by the Root Protection Area (RPA).

( The RPA is the area the tree’s roots occupy – this requires fencing and ground cover to protect it from above ground operations.) Information on protective measures for the trees on site will be provided as part of the BS5837 report.

B. Tree Hazard Surveys

Where you are concerned about your “duty of care” over a tree, then a Tree Hazard Survey is the one you require.

All tree owners have a legal responsibility as their “duty of care” to ensure others are not at risk from falling trees and branches. You need to assess the level of risk involved on your land. The risk is generally assessed based on :

  1. The level, extent and type of access that people have to the land on which the tree stands or where the branches could fall.
  2. The condition and health of the tree.

The factors underlying the condition and health of the tree will dictate how often the tree should be re-inspected for potential hazards. Advice on mitigating hazards by undertaking tree work can be suggested as part of the inspection, which you need to act upon.

C: Advice on Tree Works

Tree works on trees in Conservation Areas or on those with Tree Protection Orders on them need a “Tree Works” application.

When carrying out any tree work it is always advised that a competent arborist be consulted, whether it is a consultant or a tree surgeon. Work should be carried out in line with the British Standard, BS3998:2010 ‘Tree Work- Recommendations’. Trees should be inspected before the work is carried out too ensure the best management practices are employed.

Trees in Conservation Areas and with TPOs often have high amenity value and are well loved by their owners, so are felt to be worth the extra investment.

D: Surveys for underground utility installations

As stated in NJUG Guidelines for the Planning, Installation and Maintenance of Utility Apparatus in Proximity to Trees, there are generally low incidence of damage to underground apparatus by trees where these installed within hard surfaces ( e.g. pavements ). However trees can have variable growing patterns in term of root structure, especially if there are below ground obstructions to root growth. This can make any changes on site in the trees RPA potentially hazardous. Work on operational land for utilities often requires no LPA application, however it is considered good practice to follow BS3857 to implement tree protection methods where possible.

*** NEW SERVICE *** Tree consultancy

Bee on thorn flower

Bee on thorn flower

Norfolk Wildlife Services now offers an arborist service for trees alongside its existing wildlife services.  During development planning, arboriculture often requires consideration with ecology. Indeed with bats and trees the two often interact.

Furthermore in many of our urban and brownfield spaces, trees and woodland are frequently important features – sites on which we already offer ecology advice to clients. Specified properly in site management, trees and woodland can offer enhancement for the amenity, ecology and landscape of a site, as well as benefits for leisure and recreation.

With arboriculture being a natural synergy with our other wildlife services, we wanted to offer our customers a joined up service for all their trees requirements.  What we offer is :

  •  Tree surveys for development ( to BS5837 )
  •  Woodland management and planting advice
  •  Arboricultural Impact Assessment
  •  Planting plans for small sites
  •  Applications for tree works
  •  Liaison with planners, tree officers and statutory authorities

We are not tree surgeons, but can recommend or source you a reliable contractor should you request. Our ability to source the right contractor for your circumstances means you will have the contractor that fits your needs.

Not sure what type of tree survey you need – read our easy introduction to tree surveys

How many surveys for great crested newts ?

Great Crested Newt on handGreat crested newt captured by nettingGreat crested newt fence with bucket

We thought it helpful for clients to have set out what actual Natural England requirements are for licencing – how old your survey can be  – and how many surveys are necessary.

Natural England guidance

Natural England guidance on presently acceptable levels of survey effort is set out in their EPSL method statement form – which we present below – slightly tweaked.  This sets out both the type and age of data viewed as acceptable.  You can use the filters to find your project type.

This is our Excel table here : Great crested – survey effort and age

Deconstructing this gives some interesting insights about the age of data required, but also whether as to whether a full six surveys or repeat surveys are necessary.

Low impact licences and survey data

If we read through this table, you will find that low impact or temporary development can often use presence/absence data alone, which makes sense.  You may only need four instead of six visits ( or possibly only one if you find them first time ! ). Newt numbers decline rapidly away from ponds ( either the creatures are too unfit or simply due to dispersion effects ). The effect a long way from ponds can therefore be predicted as being low, based on their presence alone.  Far enough away and you can assume de minimus effects, and possibly avoid surveys all together.

The age of data is based on spring/summer survey seasons elapsed ( but see also later for a potential complexity here ):

Survey done Age of survey (before May[?] 2015)
March to May 2015 0 (before May 15)
2014 1
2013 2
2012 3
2011 4
2010 5
2009 6

So this year, data from the 2011 summer season is 4 years old, assuming you apply before end of May[?] 2015.  This also means that for some low impact schemes, older data will be helpful.  There are various caveats to this.

It is not 100% clear from the footnote on the NE guidance whether the age of the survey is the number of survey seasons missed, inclusive or exclusive of the present year.  It would seem more logical that 2015 data is 0 years old until March 2016, but in fact it appears to be 1 after May this year. However it would be impossible to survey, get planning and apply in the time period. We will take this point up with Natural England for clarity [ thanks to someone for pointing this out to me ].

What survey effort is most helpful ?

This raises for us an interesting question about proportionality and efficiency – what solution for survey effort allows most accurate information most efficiently ?

Given that most ponds are in the small or medium range and that large counts are generally from aggregation across ponds, should we focus more on the number of ponds involved and their functional nature ?

eDNA difficulties for presence/abscence

A difficulty of eDNA for results is that it shows us nothing of the pond’s function.

Four nocturnal visits will not only give a very good guide for impact assessment,  but also should generally reveal if the animals are breeding successfully and may turn up eggs or efts dependant on timing.

Many ponds around a breeding pond have occasional newts, but are not of high enough quality for breeding – this issue was never tackled by HSI.  Vice versa large numbers of males lecking at a pond indicate one thing.  Knowledge about successful breeding at a pond seems to us essential in stating the effects on the population.

Conclusions

So to return to the question only four surveys with presence or possibly even eDNA to prove absence could be sufficient for your needs, or you may be able to rely on existing older data. However really your consultant needs to have some understanding of population ecology to advise you on mitigation and obtaining a licence. Following guidance verbatim is not a good solution and could waste your money – sorry that slipped out.

With this in mind we advise you not to rely on this article for formal advice, but let us discuss with you how it applies to your suituation – please contact us directly if you have a licencing query or you have some observations about the article.

There is more Natural England advice on their website : https://www.gov.uk/government/publications/great-crested-newts-apply-for-a-mitigation-licence

Getting stuck in the mud at Cley

With support from members, business and the Heritage Lottery Fund, Norfolk Wildlife Trust acquired 60 hectares of land at NWT Cley Marshes in 2014. Norfolk Wildlife Services carried out baseline studies of the plants and invertebrates with particular focus on the impacts of the January 2014 flooding on the site’s ecology.

We decided to get stuck into the project (literally) to survey the saline lagoons and freshwater dykes across the site for aquatic plants such as Phragmites australis, and aquatic invertebrates such as the water boatman Arctocorisa garmari.  Initial results showed that an increased proportion of the open water on the site was unsurprisingly either brackish or saline. The effect on invertebrate species was evident during surveying as several groups were under-represented such as dragonflies.

In early summer 2015, we will survey the terrestrial invertebrates when they are most active. Some of the terrestrial invertebrates sought for include the Red Data Book ground beetle Pogonus luridipennis, or more commonly found cross spider Araneus diadematus.  Invertebrates like these are key indicators of the habitat quality and conditions present.

NWS will be running a workshop in September next year, looking at how the invertebrate population at Cley supports birds such as bittern, avocet and godwit. Check our website for more details on this “Bittern’s Breakfast and Avocets Lunch” event.

Great crested newts : surveys and assessment

Why are great crested newt surveys needed?

Great crested newt surveys are needed if they might be impacted by a development.  Normally this means where there are ponds within 250m of a site.

Great crested newt surveys help determine whether newts are present and what the state of the local populations and habitats are.

Great crested newts have suffered serious declines in numbers over the last century. For this reason, they and their habitat are protected both under both national and European law.

This great crested newt was found during pitfall trapping in 2014

Great crested newt found during pitfall trapping

Smooth newt found during bottle trapping

Smooth newt found during pitfall trapping

 

 

 

 

 

 

 

Where are they found ?

Although they can disperse long distances and are found in a range of places, they are typically within 250m of a suitable pond.

Adult great crested newts are dependant on high quality aquatic habitats in ponds for breeding.  The adults though spend much of their life on land using grassland, woodland, hedgerows. During winter they will hibernate underground and can even spend winter in building foundations.

This pond in South Norfolk was home to 120 great crested newts, 50 smooth newts and a number of frogs and toads

This pond in South Norfolk was home to 120 great crested newts, 50 smooth newts and a number of frogs and toads

The picture on the right shows a pond surveyed in 2014 that a total count of over 120 newts on one night, which is exceptional.

 

 

 

How is a survey carried out?

There are three stages :

1. A walkover to look at whether habitat is suitable

2. Surveys to identify local populations if habitat is suitable

3. Assessing if there is an impact on these populations from the development

Walkover surveys in daytime

The first stage of a great crested newt survey is normally to carry out a daytime assessment of ponds in the vicinity.  This uses a technique called a Habitat Suitability Index (HSI) assessment on any water bodies present.

Habitat Suitability Index (HSI) is a predictive tool which looks at the likelihood that great crested newts are present. It can be undertaken at any time of the year.

Low HSI scores are sometimes sufficient to conclude the likely absence of newts and are helpful in concluding abscence from a site. Where there are good quality ponds and higher scores, further surveys will be needed to say if newts are present.

Great crested newt captured by netting

Great crested newt captured by netting

Surveys for populations

There are two choices for searching for newts, “traditional” nocturnal surveys and the more recent “environmental DNA” technique ( “eDNA” ).

  • For “traditional” nocturnal surveys, these are carried out between mid-March and mid-June.
  • For eDNA surveys, these are carried out upto the end of June.

“Traditional” nocturnal surveys

Since great crested newts are nocturnal and difficult to find on land, surveys take place at night between mid-March to mid-June when they gather in ponds to breed.

Four visits are required to determine presence or likely absence, and two of these must take place between mid-April to mid-May which is the peak for breeding activity.

If great crested newts are found during these surveys, an additional two visits estimate the population size more accurately. These are also important if obtaining a licence from Natural England.

The survey will involve looking for eggs, searching for adults with a bright torch and netting for adults and larvae.  Where there is poor visibility or the site is unsafe to enter at night, then bottle trapping can be used.  This technique is more risky as it can potentially drown animals if the traps are not set correctly.

Using eDNA techniques

An alternative and new technique to work out if newts are present is to collect water samples from the pond and have them analysed for great crested newt eDNA. This technique can quickly rule out a number of ponds and avoids unnecessary night surveys.

However, if eDNA results come back positive, six nocturnal visits will be required to determine the population size.

Water samples can be collected between mid-April to end-June using a set methodology.  We have used this technique extensively and can advise you if it is suitable for your development.

Assessing impacts on great crested newts?

The Local Planning Authority needs to know that the development will not impact the species long-term.

When considering a planning application, generally they will request to know if great crested newts are present, and if so how the population will be affected, so they can consider as a “material consideration”. We can provide that assessment for you, based on years of experience.

Sometimes avoidance of impacts is possible, based on changing the timings of works or altering layouts or locations.  This avoids later needs for a licences and could be conditioned as a “method statement”.

What if there newts are impacted ?

Where there are newts AND an impact is likely, a European Protected Species Mitigation (EPSM) licence from Natural England will be required. The licence will detail how and when the work can take place, any trapping or use of protective fences, and any compensation measures like new ponds or meadows.

This will usually be conditioned on to any planning decision, but will need to be demonstrated as deliverable prior the planning stage.  The law in this area is complex, so we suggest you seek our advice on your options.

Who can do surveys ?

An experienced great crested newt surveyor is required to survey and make an assessment.  Our staff have the necessary licences and experience to do the surveys for you.

Having set out the above “rules” there are exceptions, but they are complex and we suggest you ring us to discuss.

 

 

 

 

 

 

 

 

 

Alex’s Work Placement Blog

At Hellesdon High School, we need to do a work placement in Year 11, so I have been completing work experience in the NWS consultancy office on Monday 14th and Tuesday 15th July 2014. I learned about what the consultancy does to preserve protected species and how developers have to take precautions if they want to develop areas which have been found to contain any protected species  in them ( such as bats or great crested newts ).

I also helped during my placement on evening surveys with my dad, which was probably a bit more interesting to get out and about.

The first survey was a night time newt survey at three different ponds with torches and bottle traps. My dad and I enjoyed this so much we went back there in the morning to come and see the results of the bottle trapping.  We had caught a great-crested newt and I got to handle it [supervised !] before it was released, which I had never done before and found very exciting.  The most enjoyable thing was finding out about how to prove the existence of great-crested newts – they are not very easy to find except by night.

The second survey for the placement was a bat survey on a thatched house at Hickling.  In this we counted the numbers of bats coming out of a gap in the thatch. We counted 98 bats from the same place, which means a big roost inside the roof somewhere. This was fantastic to see – so many bats in one night – the person on the other side didn’t see any all night so I was lucky ! I enjoyed learning about bat species – I hadn’t realised before that there were many different species of bat and not just one.

Finally we found a kitten on the riverside on our lunch break, so I also got to look after the rescue kitten for a bit, although I am not sure he was that happy about it. All in a day’s work at NWS !

Rescued cat with Alex

Kitten with good acting skills as Great Crested Newt in training exercise

Picture of Alex with the cat

Alex on placement at the NWS office with bemused kitten

When are reptiles active ?

Reptiles, such as adders, grass snakes, common lizards and slow worms, rely on the heat from the sun to warm their bodies in order to become active, but if it becomes too hot will overheat and seek shelter from the midday sun.

Therefore, these creatures are only active during the warmer months, typically from March to October, but are easiest to spot when the weather is not above about 18 degrees C [ so June and July are often too hot once the sun is fully up]. During suitable times, they can sometimes be seen basking in the sun on south-facing banks, or rocks, or underneath hotspots, such as discarded corrugated iron sheets. They hibernate throughout the colder, winter months, during which time they seek refuge underground or, for example, in log or rubble piles, so called “hibernaculum”.

NWS can undertake reptile surveys on sites, that are proposed to be developed. Where they are discovered on a site, we can advise clients on any mitigation required, for example reptile translocations or habitat creation.

Bat survey – what does it involve ?

Why and when is a survey needed ?

All British species of bats and their roosts are protected by UK and European law.  Local Planning Authorities (LPA) therefore take bats into account when determining planning applications and may request a bat survey.

Bat survey of barn with an endoscope by Stewart

Bat survey of barn with an endoscope by Stewart

A bat survey is required where bats could be affected by a development. Examples include sites such as old barns, buildings close to woodland and water, bridges, and old trees. The presence of bats does not mean that the development cannot go ahead. It just means that more details may be required on their use of the site.

Anyone planning to develop or demolish a building, which might affect bats, should plan for bat surveys and perhaps any mitigation needed.  The bat survey and assessment work will require an experienced, specialist bat consultant, so you need to find someone you can work with and trust.

How is a bat survey carried out ?

The initial stage of a bat survey involves a day time visit. This allows advice on the likelihood of bats being present or using the site.  If bats are potentially present, then summer bat “emergence surveys”, carried out at dawn and dusk, can then tell if the building is used as a roost. This also builds up detail about how any bats are using the site and the wider landscape. Sometimes winter bat surveys are required where there are cellars or suitable places for hibernation (e.g. ice houses ), but this are rare in East Anglia.

A similar method will apply for tree survey, although for woodlands a tree assessment method or transects may be more appropriate.

How is it used ?

The bat survey will be used by the planning authority to determine the application, and this may include attaching conditions such as timing for the development, installing a bat loft or bat boxes. Landscaping works may enhance the habitat for bats around the development.

What happens after planning ?

Where bats are significantly affected then a European Protected Species (EPS) licence will be required from Natural England.  This is issued free, but needs a bat specialist to put together the application and supervise the works. The licence set out how the works must be carried out as well as any monitoring after the development is completed.  Once this is in place the works can proceed on a clear timetable.

Our tip for when planning a development is to seek initial advice for your bat survey and mitigation well in advance to prevents unexpected delays in planning.

Further info

The Bat Conservation Trust has recently published good practice guidelines on the process for bat surveys and mitigation. These are a very helpful guide where bats are affected by development proposals.

Pee of newt and poo of bat – bat identification from droppings and DNA

Droppings, faeces, dung, poo – call it what you will these are a mainstay in the ecologists fieldcraft for id’ing species, and bats are no different.

Finding bat droppings within barns and lofts, at bat access points and under cracks and holes in trees is a good initial indicator of bat presence at a site. Knowing they are bat droppings is relatively easy, as although they look very similar to mouse droppings, when crushed they easily break down to a fine powder, made of insect carapaces.

You can sometimes determine the species or group of bat species present, purely from their droppings. Until recently this has been fairly tough, relying predominantly on how the droppings look….their colour, size, shape and texture.

Pipistrelle droppings are usually very small and regularly oval shaped, but by eye you can’t tell the difference in droppings between the three different species. Brown long-eared bat droppings are usually longer and twisted, but can often break up at the twists to look like smaller droppings. Serotine droppings are usually ‘bullet’ shaped.

However, there can be substantial differences between droppings from individual bats of the same species, with the diet playing the greatest role.

Brave souls have endeavoured to determine bat species by dissecting bat droppings using a microscope, and using the insect fragments that remain to determine what the bat’s diet is. This can then be compared to databases on preferred prey of different species. A taxing and time consuming process.

But more recently, DNA analysis technology has made identification of bat species from their droppings quick, easy and reliable. Specialist labs extract DNA from a single bat dropping (to avoid any risk of cross species contamination), undertake Polymerase Chain Reaction (PCR) to obtain the mitochondrial DNA sequence, allowing identification to species through phylogenetic analysis [ apparently !]. And, as there is no overlap in mitochondrial DNA between species.

In plain English, an almost 100% reliable way of id’ing bats by their poo !

No one squashed in destructive search

During the start of the year, Norfolk Wildlife Services had a busy couple of days, when we were asked to assist at very short notice with an emergency destructive search of a small grass field outside of Norwich, where there was concern about the presence of protected species, but emergency public water supply works were also required.

Working together Abi and Stewart and the JCB drivers used an approved method statement that protected the wildlife, but also kept the ecologists out of risk of injury from being squashed.  So it could be done safety but efficiently, the digger drivers slowly removed grassy vegetation and the top soil, then the ecologists checked closely to find and move any wildlife out of harm’s way, each taking it in turn from the other. Luckily the find was limited to three hairy caterpillar and the site was declared clear for the client to start construction on site the same day.

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