Tetrad Surveys 2001

By Harry Green, John Meiklejohn and John Partridge.

Our plans for survey work in early 2001 were severely disrupted by the Foot & Mouth Disease epidemic. We had hoped to visit westerly woods in a search for Terrestrial Caddis and when this became impossible we turned our attention to tetrads (or part tetrads crossed by the Vice County boundary) with few or no records situated in SE Worcestershire. A glance at the table published in Worcestershire Record No 9 pages 38-41 shows that this part of the county is poorly recorded. In areas where access was possible we were able to collect a surprising number of new records of common species from roadside verges along country lanes. We also found some uncommon species and good sites which will have to visit again. In all we visited 22 tetrads between late April and July, spending 1-2 hours at one chosen site in each one. We mainly recorded invertebrates and mammals, but ignored plants (unless we saw something unusual) because these have been surveyed on a tetrad basis by the Worcestershire Flora Project.

The table shows the number of records before and after our visits for a selection of groups. Columns 1- 9 are as in the previously published table. We have now added columns 10-14: we collected a few records for these groups but apart from Molluscs they remain very poorly recorded. The totals are not final: some species either remain to be identified or have not yet been entered on the RECORDER data base at the BRC.

This work has been something of an eye-opener. JWM found carabid beetles in hedge bottom leaf litter (especially in April) which he had not seen before. We found several colonies of the scarce brown ant Lasius brunneus and a couple of colonies of shining black ant Lasius fuliginosus. Our most exciting find was the Bombardier Beetle Brachinus crepitans near Honeybourne (see elsewhere in this newsletter).

We were also very surprised to find mature Tetrix subulata, the slender ground-hopper, in five tetrads in spring and early summer. We had thought that ground-hoppers, like many other orthoptera, were found as adults only late in the summer. Reference to Marshall & Haes (1988) gave the information that late instar nymphs and immature adults over-winter, mature in the spring, and lay eggs in late April, and also the preferred habitat for this species is supposed to be bare mud and short vegetation in marshy locations, which hardly matches roadside verges even during the 2001 wet spring! The other ground-hopper Tetrix undulata is more often found in woods amongst moss, and this one is the only native orthopteran species that can be found as adult or nymph at any time of the year, with some nymphs over-wintering to produce adults in the spring. We did not find any in roadside verges and hedges. The subulata records are a surprise and we suggest that other recorders look for them more closely on road verges.

We conclude, not surprisingly, that suitably selected sites along country lanes can contain many invertebrates and are well worth visiting. In contrast, the adjacent fields and their hedges situated in intensively farmed land are often very barren

In addition to the sites visited by all three of us together we all collected interesting records independently from other roadsides throughout the county. We recommend verges to you, particularly as a useful way of filling in distribution blanks for commoner species and for turning-up unusual species. Following on from his article on Natural Areas (Worcestershire Record No 9) John Day has clearly shown that such linear habitats are currently very important as places where many species survive in a hostile countryside. He is mainly considering flowering plants but the same must apply to invertebrates and other groups.

The diagram below indicates the standard letter codes for tetrads within a 10 km square.

In the tetrad column of the table each tetrad is identified by standard 10 km square letters and figures followed by the standard tetrad letter code. In some county-edge tetrads the Worcestershire part is small and you have to refer to a map showing the boundary for further information. The tetrad column lists both whole and part tetrads. The area covered is primarily VC37 which of course contains many places not now in the administrative county of Worcestershire. There are also a few areas in the present county and not in VC37. The whole is our recording area and known as Greater Worcestershire and adopted from the Worcestershire Flora Project.

Table columns are:

For each tetrad:

Top row total records at 5th October 2001
Bottom row (italics) total records at 12th April 2001

Total records for groups in the table in the tetrads before our visits was 241. Afterwards it was 926 - an increase 685 records. Not bad for three old jossers wandering along country lanes for a few hours!

Map of Worcestershire showing location of tetrads visited

The birds

Birds heard and seen were noted for 18 sites. No effort was made to search for birds and obviously more would have been seen if we had scanned around the area. Also some species are more obvious than others. Chaffinches and wrens sing frequently; rooks are heard in the distance; singing skylarks are easily noted; blackbird alarm calls are obvious; and so on. Nevertheless 26 species were noted and the total number of records for each species is given in the following table.

Wren - the bird recorded at most sites during the tetrad surveys