Taken From The Knepp Castle Estate Baseline Ecological Survey




Дата канвертавання24.04.2016
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Taken From
The Knepp Castle Estate Baseline Ecological Survey

Theresa E. Greenaway
2005
3.16 Bat Survey
3.16.1 Survey brief

A bat survey was required both as part of the baseline information needed by the River Restoration Centre and the Environment Agency prior to river restoration and as part of the overall baseline inventory of the Knepp Castle Estate. The aim of this survey was to identify bat species and habitat use in different parts of the Estate. Daniel Whitby (Whitby Wildlife Conservation) was commissioned to carry out this survey. Daniel Whitby is covered by an English Nature licence that permits the methodology specified in this survey.


3.16.2 Methodology

The Estate was surveyed on 4 occasions. All surveys were carried out under favourable weather conditions at a time of year when bats are active. Different areas and habitats were selected in order to improve the chances of recording a wide range of bats with different ecological requirements. A number of survey methods were utilised, in order for as much information as possible to be obtained in the short time available for surveying and to ascertain the sex and breeding status of at least some bats.


Time-expanded recordings were taken with a handheld Peterson D240x bat detector, which were recorded onto minidisk. Automatic bat loggers were also used to record any bats that passed a selected point. Any recordings taken were analysed on Bat-Sound software, which facilitates identification.
Mist netting and harp trapping were used to catch bats so the species, sex and breeding status of bats present could be identified. An acoustic lure was used to attract bats for capture by playing a number of species social calls.
1st August – Two nets and one harp trap were erected in Northern Wood (TQ139200). One Autobat was used to attract bats to a net. In addition a bat detector was used and the results logged.
12th August – Two automatic bat loggers were used to record bat activity along different sections of the river Adur.
29th August – One net and one harp trap was used in Great Cockshill Wood (TQ152231).
8th September - One net and one harp trap were used in Renche’s Wood (TQ148232)

3.16.3. Results

A total of 8 species of bat was recorded:




45khz pipistrelle

Pipistrellus pipistrellus

55khz pipistrelle

Pipistrellus pygmaeus

Serotine

Eptesicus serotinus

Natterer’s bat

Myotis nattereri

Whiskered bat

Myotis mystacinus

Daubenton’s bat

Myotis daubentonii

Bechstein’s bat

Myotis bechsteinii

Brown long-eared bat

Plecotus auritus

The location and breeding status of the bats, where known, is given in Table 3.16.a.


Table 3.16.a. Location and breeding state of bats recorded.

Date

Site

Species

Sex

State

01/08/05

Northern Wood

45kz pipistrelle

male

Juvenile







serotine

female

Lactating







Bechstein’s bat

male

Juvenile







Natterer’s bat

female

Lactating







Whiskered bat

male

Adult







55khz pipistrelle

Unknown*




12/08/05

River Adur TQ156201

45khz pipistrelle

Unknown







TQ142213

Serotine

Unknown










Daubenton’s bat

Unknown










55khz pipistrelle

Unknown










Natterer’s bat

Unknown




29/08/05

Gt Cockshill Wood

Brown long-eared bat

male

Juvenile







Bechstein’s bat

2 females










Brandt’s/ whiskerd bat

Female

Juvenile







45khz pipistrelle

Unknown










55khz pipistrelle

Unknown










serotine

Unknown




08/09/2005

Renche’s Wood

Brown long-eared

male

Adult










female

adult










male

Juvenile







Whiskered bat

female

Post-lactating







Natterer’s bat

female

Post-lactating







45khz pipistrelle

male

adult

* bats recorded on bat detector
3.16.4. Discussion
The Estate does not have a substantial amount of woodland, and none of the woods is particularly large. Many of these woodlands are rather isolated and scattered, but whereas a number of the oak woodlands appear likely to be very suitable for bats, others have less potential. To some extent compensating for the scattered nature of the woodlands, habitat suitable for bat flightline throughout the Estate is good with a number of large hedgerows, tree lines and double-hedged tracks and bridle paths connecting fragmented copses and small woods.
Automatic bat loggers positioned along the River Adur did not indicate high bat use especially by commuting bats, although the river is very likely to be used for foraging bats at times throughout the year. This was confirmed by information obtained on nights spent netting, when the numbers of bats observed along flightlines away from the river were always much higher than those seen or recorded along the river. This is largely because much of the river has little tree or shrub growth along its banks and so offers little protective cover for commuting bats.
Different species of bats travel, or commute, varying distances from their roosts to their foraging areas. For this reason bats caught may not necessarily be roosting on the Estate, and may be commuting on, off or through the Knepp Estate. However, those species that do not commute far to foraging sites and individuals caught early in the evening are more likely to be roosting on the Estate.
Of the eight species recorded, individuals of five species were identified as breeding females (serotine, Natterer’s bat, Bechstein’s bat, brown long-eared bat and whiskered bat) and it is likely that further surveys would reveal the presence of others, especially pipistrelle species and Daubenton’s bats. The presence of female Bechstein’s bats in Great Cockshill Wood is of particular conservation interest as this is one of Britain’s rarest mammals. While many species may breed and roost either in buildings or trees, Bechstein’s bats almost exclusively roost in trees and do not commute far from roost site to foraging areas, therefore it is very likely that there may be a maternity roost in the Estate. The presence of serotine bats is also of interest. This species has declined severely in southeast England over the past decade. It is a bat that breeds in buildings and which forages over open ground as well as in woodlands, feeding largely on large insects such as dung beetles, cockchafers and stag beetles. Under more natural grazing, the number of dung beetles could be expected to rise, which could benefit serotine bats. Identifying the exact location of bat nursery roosts would require radio-tracking caught individuals.
All bats and their roosts are protected under Schedule 5 of the Wildlife and Countryside Act 1981. Because of its rarity in Europe and the UK, Bechstein’s bat has additional protection. It is classified as Vulnerable (VU - A2c) on the 2000 IUCN Red List of Threatened Animals and protected by legislation in Annexes II and IV of the European Community Habitats and Species Directive and in Annexes II of the Bonn and Berne Conventions respectively.

3.16.5 Constraints

Bats are difficult to locate especially in their foraging areas and being highly mobile may arrive on a site after it has been surveyed. Bats also utilise different parts of their foraging habitat according to season and weather conditions. Only 4 nights survey were carried out, which is inadequate for such a large area with so many different habitats. For these reasons, some additional species may forage in Knepp whose presence remained undetected during this survey.


The deer park was not included as it was surveyed using a bat detector in 2002 (Whitby, unpublished report). This area includes a number of large ponds and a very large lake. It is known that there are Daubenton’s bats present in this area, though this species was only detected once in the 2005 survey.
The acoustic lure used to attract bats for capture by playing social calls can be selective so the species and numbers of bats caught may not be a complete representation of the present populations.
Reference:
WHITBY, D. 2002. Bats of Knepp Park. Unpublished report for Knepp Castle Estate.

45khz pipistrelle Pipistrellus pipistrellus


DESCRIPTION- The Common Pipistrelle is the most numerous bat found in Europe, and the smallest apart from the Midge Bat.
DISTRIBUTION- It is the most abundant species of bat seen in Britain, and the one most likely to be seen.
HABITATS- Found in a variety of habitats including woodland, parkland, cultivated land and also gardens and urban areas.
LIFESPAN- average of 4 years. Maximum of 16 years.



55khz pipistrelle Pipistrellus pygmaeus


DESCRIPTION- The Common Pipistrelle is the most numerous bat found in Europe, and the smallest apart from the Midge Bat.
DISTRIBUTION- It is the most abundant species of bat seen in Britain, and the one most likely to be seen.
HABITATS- Found in a variety of habitats including woodland, parkland, cultivated land and also gardens and urban areas.
LIFESPAN- average of 4 years. Maximum of 16 years.




Serotine Eptesicus serotinus

DESCRIPTION- The Serotine Bat is a large and strongly built bat, being almost as large as the Greater Mouse Eared Bat. Its wingspan is about the same size as that of a blackbird, its wings being broad and rounded in shape


HABITAT- is found in areas with open pastures, open woodland, meadows, and parkland.
DISTRIBUTION- In Britain it is not particularly common, its distribution being localised and patchy. It is most numbers in the southeast.
LIFESPAN- maximum 19 years.


Natterer’s bat Myotis nattereri


DESCRIPTION- is a medium sized bat, the long fur being a grey-brown colour on the back, and a paler grey on the undersides.
DISTRIBUTION- It is found throughout Britain.
HABITATS- The Natterer's Bat was originally a bat of deciduous woodland, but it has adapted well to new habitats and can be found in open woodland, parkland, gardens and farmland.
LIFESPAN- maximum of 16 years




Whiskered bat Myotis mystacinus


DESCRIPTION- The Whiskered Bat is the smallest of the Myotis species found in Britain. Whiskered Bat is well covered with hair, thus giving this species its name.
DISTRIBUTION-. It is thought to occur throughout Britain.
HABITAT- It can be seen in a variety of habitats from parkland, scrubland and gardens, to more rural habitats such as open meadows and wooded areas.

LIFESPAN- max. 23 years, but the average is about 4 years.





Daubenton’s bat Myotis daubentonii


DESCRIPTION- The Daubenton's Bat is also commonly known as the water bat, as it is mostly seen hunting low over open water such as ponds, lakes and canals.
DISTRIBUTION- It is a common species throughout Britain and most of Europe.
LIFESPAN- maximum of 40 years, although 18 is more usual.




Bechstein’s bat Myotis bechsteinii


DESCRIPTION - Most noticeable about the Bechstein's Bat are its large ears, which can be more than 25mm long.
DISTRIBUTION - The Bechstein's Bat is extremely rare in Britain.
HABITAT - Damp deciduous and mixed woodland


Brown long-eared bat Plecotus auritus


DESCRIPTION- is instantly recognizable because, as its name suggests, it has extremely long ears, which are about three quarters as long as its body.
HABITAT- It is predominately a woodland living species, happy around dense vegetation
BEHAVIOUR- They emerge about 30 minutes after sunset to feed. They normally hunt in close proximity to their roosts.











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