The Cookham Plan

Phase I Habitat Survey of Cookham Parish, Berkshire

4.Conclusions

4. Conclusions

4.1 Overview

• The parish of Cookham is situated south of the River Thames (which forms part of the boundary), in Berkshire. The eastern side is generally flat and low-lying (down to c.30m above sea-level). The land rises, roughly in the northwest quadrant up to roughly 100m. The soil is calcareous.

• A large percentage of the land is either urban, semi-urban, improved pasture or arable. Despite this, substantial patches and corridors of good or moderate quality habitat (the latter being important for dispersal and reduction in isolation and fragmentation, which may lead to local extinctions) exist. Accordingly, several sites have been Wildlife Heritage Status (WHS) (see appendix III). The un-surveyed urban areas also have high potential for a number of groups, particularly amphibians and bats.

• Extensive areas are owned by the National Trust, and these include some of the best wildlife habitats. Cock Marsh SSSI (target note 16) in the north consists of grazed semi-improved calcareous grassland, both low-lying beside the Thames and on higher ground where scrub is fairly extensive. It is likely to be of good botanical quality.

• Much of the grassland is of low conservation value, being improved, and heavily grazed mostly by horses, and also cattle and sheep, or is under arable crop production. There is some semi-improved grazed grassland, including in and around old, neglected cherry orchards (target note 4) and on Common Land, and small areas of damp/wet grassland.

• There are several fairly substantial blocks of mainly well-drained semi-natural woodland, with numerous mature and over-mature oaks and other broadleaved trees, which are also numerous in the hedgerows and pastures in places. These wooded areas are important wildlife habitats, as has been recognised in the Wildlife Heritage Site status of Pigeonhouse Wood (target note 2) and Beeching Grove Wood (target note 44). However, some hedgerows are broken or defunct and new plantings, both of scrub and tall tree species are scarce, so that age structure is poor. Loss of old trees due to gales has created gaps, making remaining trees more vulnerable and leading to further losses (e.g. target notes 27, 35).

• There are several small ponds and sections of ponded stream in open, sunny situations, some of recent origin. Most have at least a narrow riparian fringe. These all have wildlife interest, especially for amphibians and invertebrates. There are also shaded temporary pools in woodland (especially on Cookham Dean Common, target note 7), which are important dead wood habitat for invertebrates and if open water remains until mid-summer on a regular basis, could also be important for amphibians. There are also small damp areas in Cock Marsh SSSI with temporary ponds in open situations in the grassland.

• Widbrook Common in the south contains fairly small but valuable marshy areas (target notes 37, 41). These are also present to a lesser extent elsewhere in the south of the parish and centrally areas, along the streams. There are small reed-beds, extensive riparian fringes, small areas of sallow and Alder carr and old willow pollards. Wet woodland has also formed in some places where poplars (usually Black or Grey) have been planted and in one area next to the R. Thames on the eastern side (target note 40). 

• The carr, along with the isolated over-mature trees (especially oaks) and the neglected drier shelter-belts provide abundant dead wood habitat, particularly saproxylic (breeding in dead wood) insects, especially beetles, flies and aculeate wasps, and provide nesting sites for birds such as woodpeckers, and potential roosting sites for bats. The Nationally Scarce Stag Beetle is quite numerous in the parish (Brian Clews, pers comm.), and other scarce saproxylic species are very likely to be present.

• There are extensive urban areas - the villages of Cookham, Cookham Dean and Cookham Rise fall within the parish. There are many large, old houses with extensive gardens, especially in Cookham Dean. These areas were not surveyed, but are of considerable wildlife interest due to their maturity, as they provide stable habitat where they are not heavily managed. In particular, there are likely to be well established ponds with amphibian interest, and untidy areas, compost heaps, etc. which could hold populations of Slow-worm. The back alleys and banked lanes with mature and over-mature oaks, vegetated stone walls and avenues of tall trees including limes. The older houses are very likely in some cases to hold roosting bats. 

4.2 Recommendations for further survey work

The following suggestions are aimed specifically at species and species groups and assemblages that are most likely to be present in the habitats, and/or are of the greatest significance in terms of biodiversity and planning. Since large tracts of land are owned by the National Trust and one, Cock Marsh, is a Site of Special Scientific Interest (SSSI) enquiries should be made as to whether any previous survey data exists that is not on the TVERC database. This particularly applies to botanical surveys. Natural England will hold the SSSI designation data. Local knowledge should be used as much as possible for all taxa, and efforts to gain further details of sites and species, and access to as yet un-surveyed private land, are already underway by Brian Clews (pers. comm.).

The use of local publicity and leafleting is also likely to add very useful data, in particular in terms of garden ponds for amphibians. It is noted in the Handbook for Phase 1 Survey (Anon, 2007) that the use of publicity can have benefits is gleaning information.

4.2.1 Flowering Plants.

No data was obtained from TVERC. All grassland areas marked “SI” or “?SI”, should be surveyed by a botanist and initially classified as either high or low quality. Those considered of high quality should then be classified using the National Vegetation System (NVC). Similarly, all areas of broadleaved woodland should be classified according to the NVC system, in particular those covered by target notes, namely Pigeonhouse Wood (2) (WHS), Beeching-grove Wood (WHS) (45), Hillgrove Wood, Cookham Dean Common (7, 8) and Winter Hill (13).

All wetland areas (marked on map in pink) should be surveyed, in particular those indicated by target notes 17, 18, 21, 34, 36, 37, 40, 41 and 42,  and the carr woodland discussed under target note 32.

All botanical surveys should include precise locations of any Dark Mullein. This uncommon plant was seen during the Phase 1 (target 12) as dead stems (see target note 12) and could be more widespread. It is the foodplant of the Striped Lychnis Moth, a UK Biodiversity Action Plan (BAP) Priority Species. Cookham is within one of the major strongholds of this moth, which is centred on Buckinghamshire and extends into Berkshire and Oxfordshire. The adult has been recorded in Cookham (appendix I, vii). The eggs are laid only on the flowers, in June and July, upon which the larvae feed. Therefore, mowing earlier than mid-September would either destroy these, or delay flowering such that the plants cannot be utilised.

4.2.2 Invertebrates

Existing data is very limited, and is largely confined to butterflies, moths, dragonflies and damselflies. Stag Beetle, a saproxylic (dead wood) UK BAP Priority Species, is known to be present and quite frequent. Striped Lychnis Moth has been recorded, also a UK Priority BAP. Botanical survey for it’s foodplant Dark Mullein (4.2.1) should be followed up by a survey for the larvae, which are easily found by day on the flowers. A taxonomically wide-ranging survey should be carried out in woodland areas mentioned under section 4.2.1 should, with an emphasis on saproxylic species. Isolated over-mature trees should also be surveyed and the best breeding sites for Stag Beetle and other important species identified.

All wetland sites, namely target notes 17, 18, 21, 34, 36, 37, 40, 41 and 42, and the carr woodland discussed under target note 32 should be surveyed, both for aquatic and terrestrial species. Surveys should also include old orchards with semi-improved grassland and Cock Marsh SSSI.

4.2.3 Bats

No existing data is known at present. There is considerable potential for bat populations in Cookham. There are abundant potential roosting sites in the form of old buildings and over-mature trees. The blocks of woodland and generally quite wooded gardens and lanes provide excellent foraging opportunities. In addition, the streams provide potential foraging for species such as Daubenton’s Bat. Areas for survey are best identified by a bat specialist, but are likely to include the woodland, generally wooded areas, wetland and isolated old farm buildings.

4.2.4 Reptiles and Amphibians

Relatively little of the land is suitable for Common Lizard, which prefers lightly managed south facing grassy banks, although populations could exist along the less managed stream and ditch banks, especially along the stream north of Cookham and on Widbrook Common. In addition, the banking of the railway line could provide a source of colonists, especially the northern section north of Cookham through the golf course and towards Cock Marsh. The pond (18) and marshy area adjacent to the railway line is a possible site. Log piles have been provided here and the use of refugia (cover mats) here should be tried. 

The only known record of an amphibian in Cookham held by TVERC is of Common Frog at Cock Marsh. It appears that the lack of data is due to lack of recording. All ponds not heavily stocked with should be surveyed for the presence or absence of Great Crested Newt (legally protected species) and other amphibians. Publicity aimed at identifying potential breeding ponds in gardens and other private land should be used beforehand. Surveys should include classification of ponds.

4.2.5 Mammals. 

There are a number of Water Vole (UK BAP Priority and protected under the Wildlife and Countryside Act parts 4a and 4b) records, but the most recent is in 2001. This species, once frequent in Cookham (as elsewhere) is now possibly extinct due to the presence of mink, and recent surveys have found little or no sign of them (Brian Clews, pers. comm.). Until measures to control mink are used, further survey is probably not worthwhile. However, suitable habitat remains along the brooks in the southern half of the parish and centrally, making this a suitable area for considering re-introduction if mink were eradicated or controlled.

The larger blocks of semi-natural woodland should be examined by a mammal expert with regard to possible suitability for Dormouse (UK BAP Priority). This species needs Hazel coppice. Badger setts (protected species) should be recorded.

4.2.6 Birds

Birds are surveyed regularly and no suggestions are made as there is extensive data. Notable breeding species include Hobby, Water Rail, Barn Owl, Little Owl and Reed Bunting. The wetland and damp pasture areas are used by overwintering wading birds, notably Snipe and Lapwing.  

4.3 Local Biodiversity Action Plan Habitats

The reedbeds and lowland calcareous grassland are a Priority Habitat in the Berkshire BAP. The ponds, if they prove to be eutrophic, are also in this category.

The river, streams, wetland, calcareous grassland and standing water are Broad Habitats, considered to be of local importance, with an Action Plan written.