THE SUFFOLK OTTER SURVEY A Preliminary Report RODNEY B . W E S T a n d PETER NICHOLSON
THE European Otter (Lutra luträ) has for centuries lived and bred throughout East Anglia. Until quite recently it was thought that Suffolk and Norfolk were among the better populated areas in the country. The Otter's present status has been outlined in a report published by the Mammal Society of the British Isles (Mammal Soc., 1969). The findings, based on Otter Hunt returns, indicate that there has been a considerable decrease in the Otter population throughout the southern half of the country. One of the worst affected areas has been East Anglia, where a decrease of 5 -4% of the total Otter population was estimated for the period 1957-67. As a first assessment, the Mammal Society's report was a creditable one and its value really lies in showing how very little we know about this animal. For instance, just how many Otters are there in Suffolk and where are they? This note describes the first results of a field survey set up in July, 1969, to try and answer these questions. Methods There are well over 600 miles (900 km.) of open water and marshes in Suffolk. Obviously it would not be possible, or desirable, to survey every length of likely habitat and it was decided that a representative sample only would be taken. The survey started on Ist July, 1969, with an appeal for volunteers prepared to make regulär searches of a fixed length of river bank or marsh. By Ist February, 1970, fifty-two volunteers had agreed to help, covering approximately 40 miles (65 km.). At each visit, evidence for the presence of Otters was noted on a specially prepared report card. Weather, time, and duration of visit was also recorded. Cards were completed for all visits, including those made when no Otter signs were present. Results A total of 126 completed cards, representing 290 man-hours in the field, have been received covering the period Ist September, 1969 to Ist September, 1970. Thirty cards had a positive finding whilst a further ten were noted as "probables". The remaining returns were negative.
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The positive results included four definite sightings but otherwise identifications were from droppings or tracks. All the sightings were made near the coast. The details are as follows: 1.
T M 46. October, 1969. A sighting that followed a report of good Otter footprints in river bank mud from a locality 4J miles (7 km.) away (HA).
2.
T M 45. 26th December, 1969. Two animals observed swimming in estuary (CC/PBN).
3.
T M 34. August, 1970. A full-grown Otter seen crossing the road (caught in car headlights). It disappeared into a reedbed (MC).
4.
T M 13. 9th September, 1970. Telephone call received of sighting by non-surveyor. An Otter was seen by recorder in same locality on the following day (RW).
The Otter has a characteristic way of taking a single bite from a fish or eating only the flesh from a fowl and on three occasions the remains of prey, partially eaten in this way, were reported. Because these reports were not substantiated by tracks or droppings in the immediate vicinity they were recorded only as "probables". A further seven "probable" finds were footprints, but again the evidence could not be confirmed and the prints themselves were not clear. Discussion There are obviously many possible sources of error in the survey. Otters are nocturnal animals and their presence or absence must usually be detected from footprints or droppings. This must give rise to discrepancies between recorders as to what is and what is not evidence. Again, it is impossible to cover the whole length of suitable Otter habitat or to synchronise the surveyors so that a Single Otter cannot be recorded twice. The results obtained so far do not allow us to make many definite conclusions regarding the status of the Otter in Suffolk. We can say with some conviction that the animal is still present in the county but have little information yet regarding population size. At a minimum, it would seem likely that more than one Otter has been located by the survey, taking into account the greatest distance between sighting points (35 miles) and the known travelling distances of adults (Stephens, 1957, Erlinge, 1968). At a maximum, positive finds were obtained from eight squares (10 km.) out of a total of twenty-four squares investigated. If the probable finds are included, it indicates that there are ten squares where Otters may be present.
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Unfortunately there is no similarly obtained evidence available from elsewhere in the country, that can be compared directly with the results—a circumstance that greatly limits the conclusions and interpretations that can be made. However, the survey is to continue for a number of years and it is hoped that in this way a composite picture of the Suffolk Otter population will be built up that will put these early results into perspective. Volunteer recorders are still urgently needed and any reader who would like to help should contact Mr. R. West, 5 Dales View, Copdock, Ipswich. Acknowledgements This survey would not be possible without the work and enthusiasm of the field recorders. We would like to take this opportunity of thanking them all and hope they will continue with the work. They are as follows: M r . J. A. Abbott, Fiatford Mill Field Studies Centre. (River Stour) M r . N . Abbott, Ipswich. (River Gipping) M r . H . E. Axell, Minsmere. (R.S.P.B. Minsmere) M r . F. Royle-Bantoft, Woodbridge. (Butley River) M r . I. M . Barratt, Ipswich. (River Deben) M r . G . B. Benson, Southwold. (Benacre and Easton Broad) Mrs. Pinder Beutles, Walberswick. (River Blythe) Miss M . Bower, Felixstow. (Kings Marshes) M r . R. S. Briggs, Oulton Broad. (Oulton Broad) Mrs. B. G. Brocklebank, Higham. (River Brett) M r . and M r s . E. Bunch, Walberswick. (River Blythe) M r . M . Cavanagh, Hollesley. (Barthorpes Creek) M r . G . Clarke, Windsor. (River Blythe) M r . and Mrs. H . E. Chipperfield, Walberswick. (River Blythe) Mrs. C. Crosby, Diss. (River Waveney) M r . C. Davies, Haiesworth. (Easton Broad) M r . J. Docwra, Westleton. (Dunwich River) M r . T . Forrest, Coypu Control, Saxmundham. M r . A. C. Gatehouse, Twickenham. (Thorpeness Meare) M r . J. Geall, Leiston. (River Aide) M r . W . George, Aldeburgh. (River Blythe) Major Iain Grahame, Lamarsh. (River Stour) M r . and Mrs. J. J. Halsey. (River Went) M r . G . St. John Hollis, Ipswich. (River Deben) M r . and M r s . S. Holyfield, Orford. (Sudborne Marshes) M r . L . Howard, Woodbridge. (River Deben) M r . and M r s . J. Longe, Haiesworth. (Upper Blythe) M r . and M r s . Macdowel, Holbrook. (Holbrook Creek) Mrs. B. H . M a n n , Campsea Ashe. (River Deben) M r . C. S. Mead, Ministry of Agriculture, Bury St. E d m u n d s . M r . G . Nestling, Middleton. (Minsmere River) Mrs. F. Norway, Walberswick. (River Went) Mrs. J. Olgethorpe, Orford. (Butley River) Mrs. A. M . Orr, Redgrave. (Redgrave Lake) M r . R. J. Partridge, Orford. (R.S.P.B. Havergate) Mrs. Payne, S u d b u r y . (River Stour) Mrs. D . E. Paull-Smith, Woodbridge. (River Deben) M r . A. G . Powell, Chelsworth. (River Brett)
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M r . R. F. Pritchard, Walberswick. (River Blythe) Miss E. Roberts, Dedham. (River Stour) Miss J. L. Robinson, Boxford. (River Box) M r . J. Rolfe, Thetford. (River Waveney) Mr. F. W . Simpson, Ipswich. (River Deben) Mrs. Smith, Copdock. (River Stour) M r . J. Southgate, Westleton. (Dunwich River) Mrs. N. Walrond, Bury St. E d m u n d s . Mr. and M r s . A. E. Welch, Walberswick. (River Went) Dr. R. Mayon-White, Baylham. (River Gipping) Mr. L. F. Wright, Kessingland. (Kessingland Level)
We would also like to thank the Earl of Cranbrook and Mr. Jeremy Harris for their help and encouragement. The work was kindly sponsored by the Nature Conservancy, the Suffolk Trust for Nature Conservation, and the Suffolk Naturalists' Society. References Erlinge, S. (1968). Territoriality of the Otter, Lutra lutra, L. Oikos 19, 81. Mammal Soc. (1969). T h e Otter in Britain. Oryx 10, 16. Stephens, M . (1957). The Otter Report. U.F.A.W.