Wildlife surveys of the reservoir site prior to inundation 1971–1976

Abstract

When it became certain in I970 that construction of the reservoir now known as Rutland Water would take place, members of the Rutland Natural History Society planned a survey of the natural history of its site. Fieldwork spanned the six years 1971–76 and focussed on the flowering plants, insects, birds and mammals. The results of the survey are contained in a 70 page report to be published shortly on behalf of the Society by the Leicestershire Museums Service (RNHS 1981).

Two introductory chapters set out the organisation of the survey and the timetable of the construction programme to which it was tailored.

The third chapter consists of a detailed description of the vegetation of the watercourses and adjacent farmland based on a field-by-field survey carried out in 1971–73. It also encompasses other botanically interesting areas, such as marshes, spinneys and woods, that were affected by reservoir construction. The narrative is divided into 13 sections corresponding to sub-divisions of the survey area and appended to it is a list of the 413 species of flowering plants and ferns identified. Two of the species, panicled sedge Carex paniculata, and lesser reedmace Typha angustifolia, had not been recently recorded elsewhere in Rutland and attempts were made to transplant both to safer sites. However the fate of the complex assemblage of willows, Salix spp., upstream of Burley Fishponds, at the inflow to the north arm which could not be conserved in this way, has still to be assessed.

The fourth chapter is based on surveys of the insect life of the site extending over three two-year periods 1971–72, 1973–74 and 1975–76, this arrangement reflecting the need to adapt recording techniques as site clearance proceeded. A narrative account of the available habitat and changes in progress in each two-year period is followed by lists of all species identified and the localities in which they were found. Lepidoptera dominate these lists, with a total of 20 species of butterflies and over 150 species of moths. However, there are useful records of grasshoppers and crickets, dragonflies and seven other orders of insects, although coverage of these last is acknowledged to be patchy. One of the most striking features of the entomological report is the effect on populations of butterflies, for example, of the cessation of agricultural operations in areas that were destined to be flooded. Species such as common blue and small copper, which had been very scarce in the area during the 1960s, appeared early in the course of the survey on abandoned pasture and in successive years spread until they had colonised much of the reservoir site. Dragonflies, of which eight species were recorded, showed an apparent increase in numbers and grasshoppers colonised the large areas of temporarily abandoned grassland. The survey provided an opportunity for the investigation of the butterfly fauna of woodlands in the vicinity of the reservoir site such as those at Hambleton and Burley, but there was an inexplicable absence of species characteristic of this habitat such as the hairstreaks.

The fifth chapter, on the birds of the site, is centred on a tabulated summary of observations made at fortnightly intervals throughout the six years 1971–76, a remarkable achievement by any standards. Field records were originally summarised by parish and month and then totalled for the whole area for the ‘winter’ and ‘summer’ months. The ‘winter’ tables record the occurrence between October and March in the five seasons 1971/72–1975/76 of 99 species of birds, the ‘summer’ tables the occurrence between April and September of the five years 1972–1976 of 112 species. The lists overlap of course and the total count for the period was 121 species. A brief commentary on changes in status of particular groups of birds follows the tables. Predictably, species of open water and its margins increased in numbers from the summer of 1973 when water first began to accumulate in shallow lagoons upstream of the dam. Equally predictably, as hedgerows and woodland were cleared from the site, certain associated species, such as game birds, berry-feeding thrushes, tits and some warblers, declined in numbers. However the creation of a huge open area with a vigorous ‘weed’ flora suited small mammal predators such as kestrel and short-eared owl and large flocks of finches were seen in the winter months. The tables and summary, inadequately summarised here, bear eloquent witness to the transformation of the avifauna of an area of Midlands farmland. They put on record, for example, the first known occurrence in the area of birds such as shelduck, in 1974, and cormorant, in 1975, the first now breeding at Rutland Water, the second now present almost all year round.

The report concludes with a brief account of the mammals of the reservoir site, based on lists of sightings made at fortnightly intervals throughout the five seasons 1972–76. Again, attention was concentrated on the watercourses and immediately adjacent land, although records of bats were obtained when buildings were demolished. The records are tabulated, but the table differs from those for the birds in that the survey area was subdivided into five, permitting comparisons between parts of the site at differing stages of development. A general table for the whole site shows general trends in numbers. In all, 22 species of mammals were recorded, including pipistrelle, noctule and long-cared bats, fallow deer and harvest mouse. There is a detailed account of the fate of five badger setts within the site perimeter. The occupants of two of these were persuaded to vacate them in advance of engineering work and in the other three voluntary evacuation was followed by successful reoccupation. At the conclusion of operations at least three occupied setts remained within the boundary of the Water Authority’s land and their future seems to be assured.

The report is illustrated with some 24 photographs of the reservoir site. These include a number providentially taken prior to any work in the area, both broad landscapes and closer views of typical areas of habitat. There are a number of contrasting pairs of the same view before and after clearance and some of the destruction of habitat as it took place. Taken with the systematic records they constitute a unique record of a now vanished landscape and its wildlife.