PAST AND FUTURE OF BRITISH MAMMALS 285 



our deep rivers, notably the Thames, and nearly all its 

 tributaries, the Norfolk Broads and rivers, and almost all 

 the largest streams of Southern England, they are quite 

 common and increase. Evidence of this is shown by 

 the way in which otters have recently turned up in all 

 sorts of unexpected places, even on the smallest feeders 

 of Thames tributary streams, and on ornamental lakes 

 remote from rivers. Some very small brooks which 

 rise in the chalk downs and run into the little river Ock, 

 which in turn joins the Thames at Abingdon, have 

 lately been artificially stocked with trout, at their head- 

 waters in the sides of the hills. On two adjacent 

 streams of this kind otters appeared, and made havoc 

 among the fish. Fourteen traps were set along a chain 

 of pools to catch one of the invaders, but he escaped 

 them all. On a lake in a very waterless district of 

 Essex, far from any considerable stream, otters also 

 appeared, and have taken up their abode. They kill 

 numbers of large carp, and by the skeletons of the carp 

 a number of shells of fresh-water mussels, with the 

 ends bitten out, are generally found. The otters like 

 mussel - sauce with their fish, but will also eat the 

 mussels alone. On the whole length of the Thames 

 itself, from Gloucestershire to Hampton Court, otters 

 live and flourish, hunting only at night, and then 

 entirely concealed by the deep water. The skeletons of 

 the fish they eat are the index of their presence. 



