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THE OTTER IN SUFFOLK T H E E A R L OF C R A N B R O O K

Introduction In E n g l a n d the otter is almost entirely nocturnal and is said to need a territory of about six miles (10 km) of river to support it. It seems only to hunt over one or two miles of its territory on any one night, sleeping in a different 'holt' or 'couch' on successive days. When hunting it does not swim in the river continually but leaves it to travel along the bank at times, marking its territory by leaving its droppings (spraints) where it leaves the water. Being nocturnal it is very seldom seen but its presence can be recognised by spraints, tracks, remains of f o o d , etc. It feeds largely on fish but also eats frogs, toads, crayfish and, not being entirely aquatic, such birds, rabbits, etc., as it can find. In o u r slow running rivers spraints and other signs are less f r e q u e n t and less obvious than they are in the faster flowing rivers of more hilly districts, with many bends where Otters o f t e n cut corners, rocks and stranded logs on all of which they tend to leave spraints. The absence of signs does not necessarily indicate the absence of otters. A fioating but stable sprainting site about 2ft 6in to 3ft wide and 3ft to 4ft long would probably be used by any otter passing it. Riparian o w n e r s along the middle and lower freshwater stretches of our rivers could do useful work by installing them. Status in Great Britain B e f o r e 1960 numbers over Great Britain as a whole seem to have been more or less stable, though the extent of habitat acceptable to otters was being reduced by such factors as disturbance by an increasing number of fishermen and pleasure boats, pollution, clearance of bankside cover by River Authorities, etc., etc. B e t w e e n 1957 and 1967, however, Otter Hunts reported a d r a m a t i c fall in the number of otters found. The fall was not u n i f o r m : Scotland and North Wales were not affected at all, the D a r t m o o r O t t e r H o u n d s reported a fall of 54 per cent, the E a s t e r n Counties covering Norfolk and Suffolk 50 per cent. T h e average fall over England and Wales was 40 per cent and it is obviously probable that there was a similar fall over the much larger area where no otter hounds went. In 1968 the


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M a m m a l Society appointed a Committee of which I was a m e m b e r to investigate the position. W e found that there were signs that the fall had stopped and even been reversed in some areas but continued in Midland England where the position seemed to be serious. We thought that the cause of the disaster was probably largely due to the pesticides Aldrin and Dieldrin, the use of which was being prohibited, and that the population would build up again for that o n e reason alone, while the policy of calling off the hounds without killing which the Hunts had started in 1965 would accelerate the recovery. We recommended that that policy should continue up to 1979. In 1965 the Mammal Society had started a scheme for recording the distribution of all British mammals on a 10 km Square basis, concentrating on the otter from 1972. A good deal of the country has not yet been surveyed, a white square on the m a p (Fig 1) does not necessarily mean that otters are not present, but the m a p prepared from those returns by the Biological Records Centre does suggest that by 1977 the otter was well on the road to recovery, save in the central Midlands between the lines London-Gloucester-Preston-Goole.

Status in Suffolk since 1970 A s pointed out above, the Eastern Counties Otter Hounds reported a fall of 50 per cent in the number of otters found by them between 1957 and 1967. Since then West in his Suffolk O t t e r Survey ( S u f f o l k Natural History 16.378-388 1975) said that in 1972 'a density of one otter per 10km (6 miles) of river was a good average for Suffolk'. That agrees with the pre-1960 national average density referred to above and with more recent work on otters in southern Sweden. West also suggested that otters could be driven from the rivers Waveney and Stour by increased disturbance by fishermen and pleasure boats. Since then the D e b e n has been designated as an otter reserve for the county. West found that there were 3 or 4 otters above Wilford Bridge in 1972. That river should be regularly monitored to check on any changes in its otter population and artificial sprainting sites could help enormously. In 1977, the last year of otter hunting by the Eastern Counties O t t e r H o u n d s , a minimum of 5 otters were found on the A i d e between the mouth and Langham Bridge (West 1972


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Suffolk

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Figure 1. T h e distribution of the otter in the United Kingdom, exclusive of O r k n e y and Shetland, and in part of Ireland. Each dot represents a 10-km grid Square in which Otters have been sighted or signs of their presence r e p o r t e d between 1960 and 1976. The map was compiled in March 1977 by t h e Biological Records Centre - Institute of Terrestrial Ecology.


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records 4) and 3 on the Blythe above Blythburgh (West 1972, 3). It must be remembered that in comparing the findings of a naturalist making a survey with those of the master of a pack of Otter hounds we are not comparing like with like. The naturalist will have access to many places where the owner for ethical reasons will not allow the hunt, and so will or can cover a much wider area. On the other hand anybody who has taken a dog with a "good nose' for a walk in the country, spaniel, dachshund, retriever, etc., knows that it will smell out more animals and birds than its owner will realize are there. A pack of hounds will obviously find more in an hour than a naturalist making occasional visits in a very long time indeed. West's Suffolk Otter Survey, though, was carried out by a number of observers and over four years. It seems probable that they found most of the Otters on the rivers which were intensiveiy surveyed, and that those, like Aide and Blythe in 1977, can reasonably be regarded as typical of the whole. It seems therefore that the status of the otter in Suffolk is not unsatisfactory. Disturbance by Hunting It has been said that an otter which has b^en followed by hounds will leave that Stretch for 2 or 3 months or even more. Since the Hunts have stopped otter hunting no further firm evidence will be available so the findings of the Eastern Counties Otter Hounds in 1977 are set out below. River Aide

Dates

7 28 9 Blythe 23 Waveney 11 Ant 1 2 Wensum 22 Wissey 16

May, 30 July May, 29 July July, 6 August June, 19 August April, 11 June April, 10 August April, 15 August April, 9 August April, 20 August

Interval in Findings days 84 Find both days 62 Find both days 28 Find both days 67 Find both days 61 Blank 2nd time 131 Find both days 135 Find both days 109 Find both days 126 Blank both days

The Earl of Cranbrook, C.B.E., F.L.S. Red House Farm, Great Glenham, Saxmundham,

Suffolk

The Otter in Suffolk  
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