Hymenoptera: Aculeata) of Some Key Heathland Sites in the West Midlands Region
Total Page：16
File Type：pdf, Size：1020Kb
BR. J. ENT. NAT. HIST., 23: 2010 77 THE BEE AND WASP ASSEMBLAGES (HYMENOPTERA: ACULEATA) OF SOME KEY HEATHLAND SITES IN THE WEST MIDLANDS REGION STEVEN J. FALK Warwickshire Museum, Market Place, Warwick CV34 4SA [email protected] ABSTRACT A description of the modern bee and wasp assemblages of seven heathlands in the British West Midlands region at the end of the twentieth century is given with an indication of historic losses and recent gains. The characteristics of the various habitats that are typically present at such sites and the way that these are utilised by bees and wasps are discussed. INTRODUCTION Despite the ravages of agricultural improvement and the substantial growth of towns and cities within the British West Midlands Region (sensu modern Herefordshire, Worcestershire, Warwickshire, Staffordshire, Shropshire and the unitary districts such as Birmingham and Wolverhampton that formed the former West Midlands County), patches of lowland heathland still remain. However, huge losses have been incurred (90% in Staffordshire over the past 200 years according to DEFRA, 2003) and with the exception of Cannock Chase the remaining sites are mostly small and isolated. Today, the Region supports approximately 3000 hectares of ‘heathland’ (DEFRA, loc. cit.) of which nearly 2000 hectares fall within modern Staffordshire, 500 hectares in the former West Midlands County, 108 hectares in modern Worcestershire, and the remainder in Herefordshire, Shropshire and Warwickshire. The precise definition of heathland used by the various sources varies from ericaceous dwarf-shrub communities in the strictest sense to the larger mosaics of heathers, scrub, bracken and grassland that often occur in association. Smaller patches of heather can also be found elsewhere within acid grassland, woodland rides and post-industrial sites, especially in areas with base-poor geology that historically supported heaths and commons (often reflected by place-names containing ‘Heath’ e.g. Short Heath in Birmingham), though these small patches rarely support heathland insects. West Midlands heaths have attracted entomologists for well over a century, as revealed in the relevant chapters of Victoria County Histories e.g. Martineau (1904) for Warwickshire and Jourdain (1908) for Staffordshire. However, few detailed surveys of bees and wasps at these sites have taken place until the late twentieth century and the fauna has traditionally been much less understood than that of southern counties such as Dorset, Hampshire and Surrey, or that of East Anglia. Since 1990 the author and a number of workers including Dr Michael Archer, Jon Webb and Andy Jukes have made repeat visits to various sites of known or potential value and a number of papers and technical reports have already been produced (Falk et al., 1996; Falk & Lane 1999; Archer, 2002, 2004, 2006: Falk & Webb, 2002; Jukes, 2004). This paper collates these published and unpublished data and attempts to provide a better understanding of the contribution that heathland in this part of Britain makes to our bee and wasp fauna. 78 BR. J. ENT. NAT. HIST., 23: 2010 METHODS Survey sites Seven sites were surveyed: (i) Baddesley Common, north Warwickshire (SP274978) (Fig. 1) – a tiny heathland of a few hectares, studied by the author on several dates in 1995. (ii) Barlaston/Rough Close Common, north Staffordshire (SJ925395) – a medium- sized (approximately 21 ha) mosaic of dry heathland, wet heathland, bracken and woodland containing a small sand quarry. Studied by the author on several dates in 1994 and 1995. (iii) Devil’s Spittleful SSSI, Worcestershire (SE8270) – a 60 ha site with much sandy heathland, studied by Dr Archer on numerous dates between 1990 and 1997. (iv) Gentleshaw Common SSSI, mid Staffordshire (SK050113) (Fig. 2) – an 80 ha site near Chase Terrace supporting both dry and wet heathland, and also containing a sandstone quarry. Studied by the author on four dates in 1994/95, with subsequent visits by Dr Archer and A. Jukes up to 2006. (v) Hartlebury Common SSSI, Worcestershire (SO823706) – an 87.5 ha site with much dry sandy heathland, studied by Dr Archer between 1990 and 1997. (vi) Highgate Common Country Park, south Staffordshire (SO838899) (Fig. 3) – a 94 ha mosaic of dry heathland, acid grassland and woodland. Studied by the author, Dr Archer, A. Jukes and J. Webb on numerous dates between 1996 and 2006. (vii) Sutton Park National Nature Reserve, north Birmingham (SP1096) (Fig. 4) – a 989 ha mosaic of dry heathland, acid grassland, wet heathland and mire, carr and woodland. Studied by the author on numerous dates in 1996 and 1997. Survey methodology The nature of the surveys varied between the recorders. Much of it took the form of inventories that attempted to produce good species lists. Some visits, such as those of Dr Archer, concentrated purely on bees and wasps, whilst many of the author’s visits also covered Diptera, Odonata and butterflies, which influenced they way in which bees and wasps were sampled (with a heavy emphasis on sweeping). The author’s inventory surveys were also structured to produce separate species lists for various vegetation zones and microhabitats within the study sites e.g. bare sand, heather stands, acid grassland, wet heath, bracken, gorse stands and flowery, shrubby heathland ‘verge’. By contrast, work carried out by the author at Highgate Common between 2000 and 2002 was mostly autecological in nature, concentrating on observing the way in which the scarcer species were using the site. In all surveys, special attention was paid to both nesting and foraging areas. Examination of sandy footpaths and any sand faces across a range of dates revealed many of the fossorial species present and provided an indication of population strengths. Key forage plants were checked at the peak of their flowering, including heathers Calluna vulgaris and Erica species, bilberry Vaccinium myrtillus, cat’s-ear Hypochaeris radicata, mouse-ear hawkweed Pilosella officinarum, grey willow Salix cinerea, wild cherry Prunus avium, blackthorn Prunus spinosa, hawthorn Crataegus monogyna, umbellifers such as hogweed Heracleum sphondylium, brambles, thistles Carduus and Cirsium species, common knapweed Centaurea nigra, common ragwort Senecio jacobaea, common bird’s-foot trefoil Lotus corniculatus, vetches Vicia species and harebell Campanula rotundifolia. For genera such as Sphecodes, Lasioglossum, BR. J. ENT. NAT. HIST., 23: 2010 79 Fig. 1. Baddesley Common, Warwickshire, a small areas of heathland with a limited fauna of bees and wasps. Fig. 2. Gentleshaw Common, north Staffordshire – one of several sites with an old sandstone quarry which is much exploited by fossorial species. 80 BR. J. ENT. NAT. HIST., 23: 2010 Fig. 3. Highgate Common, south Staffordshire – the most exceptional of the sites with a list of 130 bees and wasps. Fig. 4. Sutton Park, north Birmingham – a large suburban heathland with wet and dry heath, of moderate value for bees and wasps. BR. J. ENT. NAT. HIST., 23: 2010 81 Crossocerus, Diodontus and smaller Andrena care was taken to obtain reasonable samples, as several species that are indistinguishable in the field can be present. Prolonged sweeping using a long-handled insect net was employed by the author and proved to be one of the most efficient sampling methods over mixed nesting colonies and flower-rich habitats. It was also particularly effective for obtaining pompilids, small crabronids such as Harpactus tumidus (Panzer) and Nysson dimidiatus Jurine and also the tiphiid Tiphia minuta Vander Linden in short or sparse vegetation, as these can be time-consuming insects to capture individually and are not always easily spotted in the field. Visits by the author (also covering Diptera) generally lasted for 5–6 hours and every effort was made to exploit reasonably warm and sunny weather as overcast or wet conditions severely affect the activity of bees and wasps. Visits by Dr Archer lasted from 2–3 hours and involved use of a short- handled kite net. The data have been analysed in a number of ways. The presence of Red Data Book, Nationally Scarce and Regionally Scarce species has been used to obtain a standard rarity score for each site by assigning points to the various rarity gradings as follows: 100 points to Red Data Book species, 50 points to Nationally Scarce species and 20 points to Regionally Scarce species (following Ball, 1986). The rarity gradings for Red Data Book and Nationally Scarce species were taken from Falk (1991) but some have been adjusted to allow for the fact that some gradings are now known to be strongly misleading, either due to species increasing their range and frequency in recent decades, or because they were under-recorded in the past (within the Appendix an asterix has been placed against the obviously misgraded species and a bracketed regrade suggestion that is more realistic given afterwards). Rarity scores quoted in Table 1 are based on these adjusted grades. Regional scarcity (sensu West Midlands) was assessed using the national atlases published by the Bee, Wasp and Ant Recording Society (e.g. Edwards 1997 & 1998, Edwards & Telfer, 2001 & 2002), also personal data including the official dataset for Warwickshire bees and wasps, the on-line Staffordshire checklist (available at www.staffs-ecology.org.uk). Dr Archer has also worked out a species quality score (here termed the Archer species quality score) that he has developed using the distributions and frequencies of different species in the same national atlases (see Archer, 1995 for methodology). An effort was also made to assess the quality and characteristics of the bee and wasp assemblages at these sites by examining the presence of key indicator species. The categories used were: . Species with a strong or obligate requirement for heathers (marked ‘Er’ in the Appendix) e.g. Andrena argentata Smith, A. fuscipes (Kirby), Colletes succinctus (L.) and the cleptoparasite Epeolus cruciger (Panzer), the last because it seems to be entirely parasitic upon C.