Preliminary Survey of Mammals at Lopham and Redgrave Fens

PRELIMINARY SURVEY OF MAMMALS AT LOPHAM AND REDGRAVE FENS DAPHNE

FIELDING

(Darwin College, Cambridge) most of its course the R. Waveney divides Suffolk from Norfolk and in the countryside west of Diss it runs through hitherto undrained fenland. The Fens have been acquired as a reserve by the Suffolk Naturalists' Trust. T h e Waveney, running eastwards to Diss, divides the whole proposed Reserve into north and south. To the south lies Redgrave; to the north there is Lopham. Lopham Fen is further divided into Great, Middle, and Little Fens from east to west.

In order to follow the movements of mammals in relation to the drying of the fen during the summer months a survey of the fen throughout the year would be necessary. This proved too ambitious an idea but a visit was made in May, 1966, and a short survey was made during the first three weeks of September, 1966.

The western end, that is the west end of Redgrave with Little Fen lying to the north of it, is the wetter end where reed (Phragmites) is dominant. The eastern end is drier with meadow sweet, willow herb, and tall grass (Schoenus nigricans) codominant. At the time of the reconnaissance trip in early May the fen was beginning to dry out. The ditches near the boundaries were mostly soft mud and both reed and meadow sweet were a foot high. At this time rabbit burrows and droppings indicated that rabbits, Oryctolagus cuniculus, were very plentiful in and around the copses which lie close to the border of Middle and Little Fens but that they were not apparent in the middle of those Fens.

Mole hills indicated a similar distribution of moles, Talpa europaea.

Two hedgehogs, Erinaceus europaeus, were seen, both dead, one on the road at the north-east corner of Middle Fen, and one in a ditch running from the east end of Redgrave into the Waveney.

THROUGHOUT

No traps were set on this first visit but discarded bottles were searched (see footnote). Though there were no bottles in the middle of the fen, at the entrance to Middle Fen near its north-east corner a pile of empties yielded two water shrews, Neomys fodiens, one common shrew, Sorex araneus, three pigmy shrews, S. minutus, and one bank vole, Clethrionofnys glareolus. Tracks of what was probably a water vole, Arvicola terrestris, were seen in the ditch dividing Middle and Great Fens. Mr. R. D. Pope of the British Museum reports seeing a black water vole there later, and that he has seen foxes, Vulpes vulpes, in the fens.

In September the fens were generally drier but still rather muddy. On Redgrave Fen the reed was fully grown, thick and four feet high; and on the Middle Fen the meadow sweet and

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grass were fully grown up to two feet high but sparser. These were the two areas of study.

Rabbits were everywhere on Middle Fen with piles of droppings on tussocks where the grass was nibbled or worn away: and they were also in the woods and copses as before. A few mole hills were seen beside the ditch dividing Middle and Great Fens.

A brown rat, Rattus norvegicus, was dead on the road south of Redgrave, and in empty bottles further east along the south edge there was a wood mouse, Apodemus sylvaticus, and a common shrew.

In the first two weeks of this visit twenty Longworth traps were set on nine nights in the Middle Fen. Altogether eighteen wood mice were caught and they were mostly young males. Of these three were caught amongst reeds and nettles near the ditch which divides the Middle and Great Fens, but there were none in or right beside the ditch. The remainder were caught in the meadow sweet and grass further in towards the centre of the fen, five within twelve yards of a hawthorn tree.

Over a further four nights the traps were set at the damp vvestern end of Redgrave Fen. No animals were caught in the wood but a total of seven wood mice was caught along a path which is raised and which divides off a small part of the fen.

On the path long grass grows together with brambles, sallow, and hawthorn bushes. A common shrew was also found on it.

Amongst the reed and sallow bushes close to this path two wood mice were caught in Longworth traps lying on top of last year's broken down reed, now dry; but none was caught in apparent runs underneath this.

Miss Jean Ingles helped on the trip in May, and Mr. R. D. Pope gave much help and advice during the September visit.

The Earl of Cranbrook suggested the investigation and made it all possible.

L I S T OF SPECIES

CAUGHT

Erinaceus europaeus Talpa europaea Sorex araneus Sorex minutus Neomys fodiens Oryctalagus cuniculus

Clethrionomys glareolus Arvicola terrestris Apodemus sylvaticus Rattus norvegicus Vulpes vulpes

FOOTNOTE

Morris and Harper (Proc. Zool. Soc. Lond. 145, 143-160, 1965) reported that discarded bottles often contain the remains of small mammals. T h e animals probably enter the bottles when looking for food and are even able to force their way through a narrow neck by pushing with their feet against firm ground: once in they can be trapped as they cannot climb u p the smooth glass sides of a bottle lying at a greater angle than 15° to the horizontal. Botties with an internal neck diameter of 16 m m upwards were found to trap both shrews and rodents though the most effective seem to be those of milk bottle size (20 m m internal neck diameter) and upwards. T h e practice of examining discarded bottles can be a useful tool in the collection of mammal distribution records.