THE WATER RAT 495 
unless enraged by being hurt—makes its entry quite peace- 
ably, and receives all further captives in a tolerant spirit; but 
a freshly caged Water Rat, like a Lemming, expects to be 
attacked, and generally has a short bout with all its fellow- 
captives in turn,’ thus indicating that it lives in colonies 
or pairs each in its own territory apart from its neigh- 
bours. Of course when the colonies become crowded the 
sense of “property” indicated above cannot be so readily 
satisfied, but where the animals are not common, and during 
the breeding season, they have distinct ‘‘ beats,” as observed on 
the river Mole, near Reigate, by Mr Adams. These beats 
extend for about 20 yards along both banks, and the entrance 
of a stranger is always vigorously resisted, even by immature 
individuals whose riparian property is invaded. This sense of 
property rather interferes with the animal’s character in 
captivity, since although naturally gentle and unaggressive, it 
bites furiously if its nest or its person are interfered with, and 
cannot be handled unless thoroughly familiar with its owner. 
Although “plagues” of Water Rats are not frequently 
reported, there is evidence that the numbers of these animals 
are subject to the same extraordinary fluctuations as those of 
Grass Mice.” J. L. Knapp relates*® that a large stagnant piece 
of water was thus suddenly infested one summer with an 
astonishing number, where none had previously been known ; 
they disappeared in the following winter. Mr O. V. Aplin 
commenting* on their varying numbers in Oxfordshire, 
suggests that many perish during hard winters. Early in 1896° 
a serious “‘ plague” was reported from Read’s Island, consisting 
of some 600 acres of reclaimed pasture in the Upper Humber 
adjoining South Ferriby, Lincolnshire. This is said to have been 
reduced to the conditions of a rabbit warren by the burrowing 
propensities of the animals, which were described as “quite 
1 Cocks, 47S. 
2 As also in Norway, where, however, Collett reports that the increase is chiefly 
local, and is coincident with that of Microfus and Lemmus. In Scotland, also, 
Service (Annals Scott. Nat. Hist., 1896, 206) noted a marked increase during the 
“vole plague” of 1891-3. 
3 Journal of a Naturalist, 1829, 142. 4 Zoologist, 1891, 304. 
5 See R. Payne-Gallwey, Fe/d, 22nd February 1896, 294; F. Boyes, Journ. cit, 
29th February 1896, 336; also, Hastern Morning News of same date. 
