THE WATER RAT 48; 



Water Rats may be regarded as large Grass Mice which 

 have adapted themselves to a predominantly aquatic life, but 

 without specialising so far as to lose the power of resuming a 

 terrestrial existence. Their love of water is shown in their 

 comparatively long tail, used no doubt for steering purposes ; 

 thicker, more beaver-like coat ; well developed aural valves ; 

 reduction in size and number of foot-pads ; and slightly fringed 

 feet. In other respects they have not been specially modified 

 in any really important detail for amphibian existence ; but 

 their life by ponds and watercourses has led them to construct 

 a somewhat peculiar type of burrow, and they show a preference 

 for certain water-loving herbs, which are not usually in the 

 path of the ordinary Grass Mice. 



Our own Water Rat, although a comparatively large 

 animal and hunted by many predatory creatures, to which it is 

 extremely palatable, manages to exist in numbers in a region 

 wherein all other members of its sub-family, except the smallest, 

 have been exterminated. Several large voles allied to or 

 identical with the Skomer Bank Mouse, the Northern and 

 Orkney Grass Mice and the Snow Mice,' flourished in south 

 Britain in the late Pleistocene period, but now exist only in 

 the sanctuaries afforded by islands or mountainous regions. 

 The Water Rat alone remains, partly no doubt because it has 

 no direct competitors amongst the members of its own sub- 

 family and partly because it has adopted the happy expedient 

 of relying on water for a retreat from its enemies. By doing 

 so it incurs the risk of being snapped up by herons,^ pikes, 

 large eels,* and trout, and it is a staple food of owls, stoats, 

 polecats and, perhaps, foxes ; but it avoids many of the other 

 enemies of its tribe. Like all water dwellers in cold or temperate 

 countries it suffers from inundations which drive it from its 

 burrows ; from frost, a combination of these two being most 

 inconvenient ; or droughts ; but on such occasions it is always at 

 least as much at home on dry land as would be a Grass Mouse 



' Chionomys, see p. 470. 



^ J. G. Millais has seen a heron kill a small one, and T. A. Coward and Charles 

 Oldham find the pellets thrown up by herons {Cheshire, 55) consisting almost entirely 

 of the fur of Water Rats. 



' Nat. Hist. Trans. Northumberland and Durham, v., 1877, 341 ; for an eel 

 seizing a Water Rat's tail, see J. D. Patchett, Field, 12th September 1891, 431. 



