Summer bat surveys

The bat survey season is well and truly underway and at NWS surveys are taking place almost every day of the week. Initial surveys are undertaken to look for evidence of bats and if found then a minimum of three nocturnal surveys (dawn and dusk) may be required during the main survey season, i.e. May to September.

During a dusk survey, surveyors watch the building from 15 minutes before dusk and 2 hours after dusk to watch for any bats emerging from the building. A bat detector and a recording device are used to record any bat calls which are then analysed to confirm the sightings and to identify species. Target notes are also recorded on a map so any points of entry can be identified.

During a dawn survey, surveyors watch the building for the 2 hours before dawn (which means a very early start!). The same method is used as in a dusk survey but the surveyors are mainly watching for bats to return to roost.

These surveys can be really interesting and exciting if there is lots of activity at the site but they can also be a bit boring if there isn’t much going on (you are essentially staring at a building for 2 hours…. potentially at 2.30am!). It can be worth getting up super early though if you get a close encounter with a bat like at a recent site where Brown Long-eared bats were roosting just above our heads in a barn.

Brown long-eared bat

Brown long-eared bat

Mitigating for great crested newts

Since starting great crested newt surveys in mid-March 2015, about 20% of the 75 ponds surveyed across Norfolk contained newts. For these sites, their development may now require a “European Protected Species Mitigation” ( EPSM ) licence, granted by Natural England after planning permission is given.

Lemonade and great crested newts

Bottle Trap

Bottle trap used in great crested newt surveys

We devise the mitigation strategy for clients based on where and how many newts are present.

To estimate numbers, we make six nocturnal counts via netting, with “bottle traps” (1.5 litre lemonade bottles) and spotlights. This indication of population size is used to devise a proportional strategy, ensuring that your development does not adversely affect newt populations.

Compensatory habitat

The EPSM licence needs to provide “compensatory habitat” at least equal in extent to that lost by development.  Newt habitats include scrub, grassland and woodland, but also often brown field areas, especially near old gravel or brick pits.  Ideas to think about when designing “compensatory habitat” are:

  • Restoring existing ponds to make them more suitable for great crested newts by clearing out shading scrub or desilting.
  • Creating brand new ponds: often also an attractive landscape feature (but no fish please and balancing lagoons aren’t suitable!)
  • Making wildflower meadows: good foraging habitat for newts plus an attractive feature managed well;
  • Planting woodland belts and hedgerows makes excellent shaded habitat for newts with leaf litter and logs, plus good for site landscaping, and corridors for newts to travel along to safely get from one area to another.

The bucket stage

If work cannot avoid impacting great crested newts, the development will need fencing off and trapping out with “pitfall traps” (buckets) to capture them and move them to safety.   Trapping normally takes place in autumn or early spring as it requires both suitably wet weather, but reasonable temperatures for the newt activity.

The number of nights trapping depends on the population, varying between 30 and 90 nights with additional needs where breeding ponds are removed.  If the fencing fails during building, then retrapping may be required, so investment in a decent spec fence is worth some thought. Generally you will need to keep the perimeter up from start to finish.

To create the compensatory habitat for a site near Dereham, we cleared ornamental shrubs and seeded the bare banks with wetland wildflowers around an existing pond, creating excellent refuges and invertebrates to hunt. Enclaves of wildflowers and trees were connected via thick hedgerows running around the boundary of the development, linking to hedges and ponds in the landscape.  Post development, the 2015 recount of newts showed numbers of breeding newts have remained consistent at 85, and that the mitigation had been successful.

Creating a bespoke boudoir for bats

As part of the re-development of a small brownfield site within Norwich, NWS were commissioned by RGW Portugal Ltd to undertake bat surveys of two small buildings. One of these was found to support low numbers of brown long-eared bats Plecotus auritus and soprano pipistrelles Pipistrellus pygmaeus, which were using the building for roosting in summer. The buildings needed to be demolished in order to create space for two new residential homes, and so NWS prepared a European Protected Species Mitigation licence for bats which was granted by Natural England.

Brown long-eared bat captured during demolition work

Brown long-eared bat captured during demolition work

NWS licensed ecologists supervised the demolition of the buildings in August, removing a roosting brown long-eared bat which was found along the central ridge beam and relocating this within a bat box which had been placed on a mature oak tree in adjacent woodland.

RGW Portugal Ltd were keen for an environmentally sensitive development and had included bike stores within the design to encourage the use of green transport. These features provided the perfect opportunity to create a bespoke bat loft for both species of bats to use. The loft was constructed above the bike stores, using a lined and tiled pitched roof to generate warm internal temperatures. Two carefully-placed bat access points were installed along the ridge and at both gable ends, allowing a number of entry points whilst reducing potential for light ingress and draughts. The ridge beam was formed using rough-sawn timber to create a suitable surface for bats to cling to, and bat batons were also installed along the inner walls to provide additional perching points.

The last features of the bat loft have just been installed this winter and NWS are hopeful to see use of this loft by bats when they return to roost in April.

 

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.

New winter homes for great crested newts

Since 2000, NWS has worked on development sites that support great crested newts, and in 2014 successfully assisted Saffron Housing in obtaining a European Protected Species Mitigation (EPSM) licence for this species on a residential development in South Norfolk. Nationally great crested newts have suffered huge declines and so are protected by European and UK law. Norfolk is one of the species’ strongholds, with greatest numbers of breeding ponds found on heavy clay soils.

With great crested newts present in ponds around the area and using the grassland on site to move between these, the EPSM licence was required during construction to protect these amphibians and provide compensatory habitat.

NWS staff supervised the installation of “newt exclusion fencing” and carried out pitfall trapping to remove newts from harm’s way. Great crested newts only use ponds for breeding and spend the rest of the year on land. The team focussed the compensatory habitat on features suitable for use during this “terrestrial phase” and supervised the creation of what was dubbed “Newt Nirvana” by the developer:  a wildflower grassland with hedgerows and scrub.

A key feature was the creation of three earth and stone mounds, which newts will use

This hibernacula has a rubble/log base to provide crevices for overwintering newts

This hibernacula has a rubble/log base to provide crevices for overwintering newts and is covered with turf to create stable temperatures through winter

during winter, called hibernacula. Great crested newts hibernate when winter temperatures drop below 5oC, normally from October or November. They typically hibernate underneath logs, within mammal burrow or tree roots, and even in building foundations. The hibernacula on site were designed to provide a number of sheltered crevices using logs and rubble, topped with turf to prevent exposure, whilst also ensuring newts were safe from flooding. Here the newts can remain protected until they emerge in late February or March to begin breeding in ponds.

Invasive Non-Native Species – Japanese Knotweed – successful control

Our team are trained to recognise Invasive Non-Native Species [ also called INNS ]  on survey sites and advise on issues with their control.

One of the most pernicious, we encounter is Japanese Knotweed, which is an Asian species originating as a garden escape, spread via root fragments of its rhizomes, often from fly tipping or contaminated topsoil. Once established the underground rhizomes, Continue reading

Landscape design completed for Cley Marshes education centre

At Cley Marshes, Norfolk Wildlife Services are working with Norfolk Wildlife Trust on the new Simon Aspinall Wildlife Education Centre. Simon Aspinall was a naturalist who made important contributions to ornithology and conservation, and the new centre will reflect his love of nature, wildlife and education.

After extensive consultation and review of a number of landscape designs, the team has gained planning approval from North Norfolk District Council for a planting scheme around the centre, which will encourage butterflies and wildlife to the site and enrich the visitors’ experience.

Maritime turf and shingle planting will create formal “garden” areas, while new trees and shrub planting, using species and structure to match existing landscape elements, will ensure that the new building will blend into the surrounds and appear coherent with the existing centre.

NWT Project Manager, Ian Leatherbarrow, commented, “Norfolk Wildlife Services prompt response to developing an attractive, cost effective landscape design means that we can start work on the project knowing that the outdoor element of the work will be successfully delivered.”

Norfolk Wildlife Trust is one of our key clients; we work closely with them on many of their reserves. Other successful outcomes for the Trust include: transformation of land at Upton Broad and marshes from arable to grazing marsh and assisting with the development of Hilgay and Methwold as a wetland Living Landscape.

New landscape design for Cley Marshes

At Cley Marshes, Norfolk Wildlife Services are working with Norfolk Wildlife Trust on the new Simon Aspinall Wildlife Education Centre. Simon Aspinall was a naturalist who made important contributions to ornithology and conservation, and the new centre will reflect his love of nature, wildlife and education.

After extensive consultation and review of a number of landscape designs, the team has gained planning approval from North Norfolk District Council for a planting scheme around the centre, which will encourage butterflies and wildlife to the site and enrich the visitors’ experience.

Maritime turf and shingle planting will create formal “garden” areas, while new trees and shrub planting, using species and structure to match existing landscape elements, will ensure that the new building will blend into the surrounds and appear coherent with the existing centre.

NWT Project Manager, Ian Leatherbarrow commented, “Norfolk Wildlife Services prompt response to developing an attractive, cost effective landscape design means that we can start work on the project knowing that the outdoor element of the work will be successfully delivered.”

As one of our key clients, NWS works closely with Norfolk Wildlife Trust on many of their reserves. Other successful outcomes for the Trust included the transformation of land at Upton Broad and marshes from arable to grazing marsh; and assisting with the development of Hilgay and Methwold as a wetland Living Landscape.

Bats in the thatch at Norfolk Wildlife Trust’s Hickling reserve

Norfolk Wildlife Services have been asked to survey bats in the thatched wardens house at the NWT Hickling, Norfolk, and offer advice on their protection.

At Hickling, Stewart has undertaken an assessment of the bat roost within the warden’s house, which requires rethatching.  The bat colony has been known about for several years, with bats flitting around the eaves on summer evenings catching midges and mosquitoes swarms from the adjacent wetlands.  As such the Hickling warden John Blackburn was keen that the thatching work didn’t accidentally block entrances or affect the bats, and so called on Norfolk Wildlife Services to offer specialist advice well in advance.

John Blackburn, the warden, joked : “People talk about taking work home with them, but in this case a bit of the nature reserve seems to have moved into my house.  It’s easy to forget that there is a whole night shift at Hickling, that starts up when the reserve closes.  Nocturnal creatures such as bats are as integral a part of the ecology of Hickling as it’s bitterns.”

Bats will not normally roost in thatch, since the reed can very easily pierce or snag their membranous wings, and in rural Norfolk areas typically use Dutch pan tile roofs, which have abundant snug gaps.  At Hickling, based on droppings found, the bats are suspected to roost within a cavity wall in the loft, perhaps sardined into the inside of a breezeblock, where they are not visible in the daytime.

In order to find the roost location and count the number of bats using the roost, nocturnal surveys will observe both their emergence and then around dawn their carousel display as they settle to roost.

Stewart, an ecologist at Norfolk Wildlife Services said:

“We will use specialist bat detectors, which many people will be familiar with, that reduce ultrasonic bat echolocation calls to an audible frequency. The echolocation calls will be recorded digitally, allowing later analysis to confirm which species were present. We have a good idea where bats are emerging from as droppings are regularly found beneath a hole around the roof rafters, but will be relying on good vision to confirm this and any other potential roost sites within the building. The most likely species we will find are soprano pipistrelles, but we know there are also two other pipistrelles at Hickling as well as Natterer’s and Daubenton’s bats, so it should be quite exciting.”