Field visit to Greetwell Hollow and Whisby Nature Park, Lincoln. June 24th 2006

Greetwell Hollow is a name which may conjure visions of an untouched, enchanted glen remote from all traces of human activity. In fact, it is a brownfield site adjacent to light industrial, retail and residential areas of the city of Lincoln. Its iron-ore extraction history was described in the notes about this meeting in Mollusc World 10. Brownfield sites are much under-rated hunting grounds for the naturalist. Often they have much higher biodiversity than nearby greenfield sites. Species often include colonists which are not known elsewhere in the area and which are able to cope with the unusual habitats created by industrial activity. Greetwell Hollow has been derelict for many years and, from the interior it is easy to forget the proximity of the city. The Lincolnshire Wildlife Trust is to be congratulated on the way they have managed to reduce the problems of litter, vandalism and motorcycle disturbance to manageable proportions.

In his report on the field visit to Bredon Hill, Harry Green noted that one quality required by the course leader was not any great ability to identify molluscs. Just as well. This is the third course I have been privileged to lead and on each occasion it has been the enthusiasm and experience of the other members of the group which has enabled such a thorough job to be done. I was particularly fortunate that Adrian Norris appeared. His ability to identify small species at a glance is matched only by his ability to recognise incompetence when he sees it. I was rapidly relieved of the task of recording species and I am grateful to Adrian for compilation of the lists for both the sites we visited. I am also grateful to David Lindley for his comments below on the significance of some of the shelled molluscs.

I believe there was a sweep on the number of species found (although having being brought up in a strict non-gambling household I turned my deaf ear to this matter) and there was an optimistic suggestion of 30. After the 30 species mark had been passed speculation mounted about the magic 40. With a mathematical background I could see nothing particularly special about 40 (I know it is the smallest integer for which the quadratic expression n2 + n + 1 has a non-prime value, but that seems to have little relevance to conchological pursuits). On enquiry I was told that 40 species entitle you to the next largest size of blob on the 10 km maps. (I have since checked on this and find it is true for the 1976 atlas, but it is 46 in the 1999 atlas. Adrian - how can you be so up-to-date with molluscan nomenclature but so out-ofdate with dot size conventions?) We ended the morning with 39 species for the reserve. Fortunately for the quarantephiles, we now have three more records - one slug seen on my preliminary visit in the spring and two small snails found in samples taken for examination at home. This total included 42 species newly documented for the reserve and 16 new to the 10 km square TF07. We were fortunate that Brian Eke, the LWT voluntary warden who has done so much to make the reserve what it is, was able to be with us for the morning and show us where we might find molluscs.

David noted that it was interesting to find Vertigo antivertigo at Greetwell. A glance at the current atlas will show that it is not common in this area, there is a record from the 10km square to the east and some old records further west - but that is all. For it to have survived at such a site is interesting. It was found at one of the spring heads which, even in the dry weather, had remained very wet. The same can also be said for Vertigo pygmaea which was seen in good numbers and easily found, though there are more records in Lincolnshire for this species. It is also worth commenting upon Pupilla muscorum which, again, was easily and quickly found. Is this species a good coloniser or has it survived the iron extraction? I tend to favour the latter; there must have been areas within the site that remained fairly free of disturbance, which has allowed it to ‘cling on’ until such time as the site has become more favourable.

The afternoon was spent as Whisby. Again, this is an LWT reserve, on former gravel pits. Phil Porter, the warden, showed us round. Whisby is very popular with local people because of its proximity to the city and its abundance of wildlife. Habitats include lagoons, grassland, meadows, swamps and woodland. Phil conducted us from one potentially interesting site to another. I think he was surprised as he shepherded us from our pond dipping session to the next point of interest, when the whole group, as one, diverted to a not-apparently-interesting pile of logs and started rolling them over. Good tactics with several species lurking below, taking shelter from the heat and dryness. Whisby straddles the boundary of a 1 km square, and the species list separates these two. Whisby, with its resident warden and visitor centre also boasted a species list. We managed to add considerably to this and to find some new 10 km records. David commented that, whilst fewer species were found at Wisby, it is fair to say we spent less time there and did not have time to visit all the habitats available. Certainly further freshwater work could be carried out as there were some obvious species missing. The discovery of Pisidium pulchellum was interesting, once more it is not a common species in this area though it is recorded from some 10km squares not too far away.

A final thought - one slug was found in a dried, overgrown pond liberally strewn with debris from human activity. It reminded me of the description of the typical British pond given by Flanders and Swann in their song - the Bedstead Men. What a pity their last line ended with 'and a broken bedstead there'. For 'broken bedstead' substitute Boettgerilla and you will be close to the truth.

The team

Ron Boyce, Adrian Norris, David Lindley, Rosemary Hill, Chris du Feu, Jane Bonney, Brian Eke, Phil Porter.

Species list

Nomenclature is according to the annotated list in the Journal of Conchology 38, Part 6, November 2005.

Greetwell Hollow TF07

Whisby SK96