Invertebrate survey successes for Cley Marshes

coastal lagoon

Ben Christie sampling lagoonal invertebrates


Our follow-up survey on Norfolk Wildlife Trust’s new marsh at Cley has found five invertebrate species of conservation importance, including lagoon sand shrimp Gammarus insensibilis (legally protected) and mud snail Ecrobia ventrosa.

The Trust commissioned a specialist baseline study on their new land at Cley Marshes when they purchased it in 2014. This was surveying the plants and invertebrates in the site’s ditches, dykes and scrapes.

Since then, the Trust has carried out extensive work on the marsh to convert it from wildfowling ponds to a nature reserve and wanted to repeat the surveys. The plan was to compare with the 2014 baseline and identify any changes resulting from the work.

Twelve sample ditches and lagoons sites from the 2014 survey were re-surveyed for aquatic invertebrates, following the same methodology. For each, we took two dip-net samples to collect a crosssection of the aquatic invertebrates in the water: one in underwater vegetation near the shore; and one reaching out into the depths of the open water.

Ben Christie, our invert specialist said: “By first grouping inverts into taxonomic orders and then using specialist microscope keys for identification, we were able to efficiently identify the specialist communities for every sample site. This allowed both a direct comparison of communities in 2014 and 17, but also showed distributions for five invertebrate species of conservation importance.

“Norfolk Wildlife Trust can now fully assess the benefits of their management on invertebrates as well as the birds and other wildlife who are dependent on them in the food chain.”



Students Go Batty For Work Experience


An unusually warm autumn has meant more bats out in the evenings later in the year than normal. This provided students from East Coast College with a chance to gain bat survey experience on two different dusk surveys.

Ben Moore, Assistant Ecologist at NWS, said: “Our first site was along a stretch of the upper reaches of the river Bure surrounded by wet grassland and woodland edge. We had great views of noctules, one of our largest bats, as they foraged high in the twilight over the open grassland”.


East Coast College students gain experience by helping with bat surveys

“The students heard the characteristically slow slapping calls of the noctule, which distinguished it from most other species. Once it had become darker, we saw bats over the water, their white underbellies still visible. Coupled with distinctive rapid ‘machine gun’ like calls, this identified Daubenton’s bats using the river to feed on mosquitoes and other tasty morsels of the flying insect variety.”

“The second survey site was along a stretch of the Marriott’s way, a well-sheltered commuting and foraging route for bats with its tree-lined embankments. Here we observed common pipistrelle and soprano pipistrelle and used a handheld frequency detector to tell them apart as they zipped up and down the disused railway.””


Urban wildlife : using IR cameras for badger surveys

It can be difficult to prove the presence or absence of badgers, as they are shy when near their setts. Badgers also have an extremely good sense of smell and can detect the scent of humans easily. To stand a better chance of recording them a camera can be used to reduce human scent near the sett.

We recently used our night vision trail camera to assist a client on the outskirts of Norwich who is seeking planning permission for a new build. We had identified a badger set in close proximity, which may have been home to not only badgers, but also other burrowing animals who often co-habit or move in, if the burrow has been abandoned.

The camera works on an infrared motion trigger, capturing pictures or videos of animals moving nearby. In this case there was a family of foxes and some hedgehogs, but we were able to prove there were no badgers present at the sett.

Camera catching a passing fox

camera shy squirrel

Can eDNA detect great crested newts later in year?

Natural England [1] only accept “negative” eDNA results for newt licencing where efficacy has been proven ( e.g. between the above dates and by trained personnel ) . “Positive” results clearly have no such limitation.

The pilot work [2] on using eDNA for detecting newts relied on comparing conventional field survey techniques to eDNA and comparative results were therefore only available during their sampling period i.e. mid-April and late June. Detection rates for sites where newts were known to be present were 99.3% using professionals and 91.2% using volunteers.

The report [ 2 ] states that “Overall, collecting eDNA appears to be a highly effective method for determining whether Great Crested Newts are present or absent during the breeding season. We do not know how effective the method is outside this period.”

Natural England indicates the peak season for surveying for larvae is August, so in theory these should be detected by later eDNA tests.

eDNA declined rapidly once great crested newts were removed from experimental ponds [3] – to undetectable levels over 1-2 weeks. Ponds could therefore have been utilised by adults earlier in the season e.g. for foraging, but the absence of larvae would point towards absence of successful breeding.



[2] Biggs, J., Ewald, N., Valentini, A., Gaboriaud, C., Griffiths, R.A., Foster, J., Wilkinson, J., Arnett, A., Williams, P. and Dunn, F., 2014. Analytical and methodological development for improved surveillance of the Great Crested Newt. Defra Project WC1067. Freshwater Habitats Trust: Oxford.

[3] Thomsen, P., Kielgast, J.O.S., Iversen, L.L., Wiuf, C., Rasmussen, M., Gilbert, M.T.P., Orlando, L. and Willerslev, E., 2012. Monitoring endangered freshwater biodiversity using environmental DNA. Molecular ecology, 21(11), pp.2565-2573.

Spring Newsletter 2017

All our latest wildlife news in our Norfolk Wildlife Services’ Spring Newsletter 2017.

In this issue we bring you :

Or click to download a pdf copy

Blackthorn flowers and hedgerow assessments

March marks the meteorological start of spring and it’s also the time to start looking out for the first blackthorn [Prunus spinosa] flowers.

blackthorn flower

Photo © Ian Calderwood

Blackthorn flowers are easy to spot because they appear before any of the hedgerow leaves.
As soon as you spot the first flowers you’ll suddenly begin to notice whole swathes of them.  At this time of year of you might be forgiven for thinking all hedgerows are predominantly blackthorn, but our hedgerow assessments can offer an insight into the diversity of hedgerows.


Why are hedgerow assessments important?

Hedgerows are protected under the Hedgerows Regulations Act 1997 and these are part of planning regulations. The Regulation was brought into effect due to the changes in agricultural practices which saw a rapid removal of hedgerows from the countryside.

“Hedgerows have their part to play in helping us to respond and adapt to climate change, providing conduits through which wildlife may move, and protecting soil, livestock and property against extreme weather events. They even help to lock up carbon and provide a sustainable source of fuel. ” Hedgerow survey Handbook (2007)

This protection covers hedgerows over 30 years old and over 20 metres long (or if shorter, connected to other hedgerows at both ends or part of a longer hedgerow).

Hedgerow removal is a tricky subject and a landowner who wishes to remove a hedgerow must serve a Hedgerow Removal Notice in writing on their local planning authority. The authority then has to determine whether or not the hedgerow is ‘important’ and whether or not to issue a Hedgerow Retention Notice.

What makes a hedgerow important?

This is where hedgerow assessments come into their own.


Photo – Emily Nobbs

We need to assess how many woody species are within the hedgerow, how old it is and whether the hedgerow is associated with any archaeological sites of interest.

There are lots of different combinations of features that make a hedgerow important, such as being at least 30 years old and have a minimum of 6 woody species and a supporting bank and/or ditch running along its length.

Woody species include alder, wild cherry, dogwood, black-poplar, hawthorn and of course blackthorn.

The NWS Arboriculturist can help

Jim Allitt is our resident Arborculturist and can help with any questions you have regarding hedgerows and what you can and can’t do.  Having a hedgerow assessment early on in any proposed development will allow you to understand more about the hedgerows you are working with and help you to plan any mitigation.

So the next time you see a hedgerow full of blackthorn flower don’t dismiss it, you may be looking at a very important hedge!

Survey season ahoy!

It’s that time of year again when we start planning for the forthcoming survey season.

However, don’t think we have been twiddling out thumbs since November!  There have been Phase 1 surveys to carry out and arboricultural impact assessments to write – but now we’re coming up the busy season.

By planning ahead and taking account of various seasonal constraints posed by many protected species we can help project managers avoid potential delays in submitting planning applications or enabling construction works.  For example the breeding season for great crested newts typically starts in mid-March and continues until mid-June (subject to weather), which dictates the optimal window for surveying.

Survey calendar


Click on the image to view a calendar that identifies the seasonal constraints associated with ecological and protected species surveys.


In anticipation of the survey season we’ve been tidying up the equipment shed, ensuring we have all the kit needed for the months ahead:

  • The great crested newt bottle traps have been made making sure all the associated canes all have hazard tape on so we don’t lose any.
  • The bat detector batteries are all on charge and the pencils have been sharpened.
  • There have been trips to the DIY store and roofing felt cut to size for reptile surveys.
  • The life-jackets have been sent for a service ready for water based surveys and our wellies have all been cleaned.

We look forward to working with you during this survey season and throughout the year.  If you have any questions about surveys and when they can be undertaken please do let us know.

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.


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 :