138 BRITISH MAMMALS 



over all the portion that is visible. The general colour of the upper 

 surface is a bright raw-umber, the chin, throat, belly, and inside 

 of the limbs being grayish-brown or yellowish-gray. Occasionally 

 British otters are spotted with white, especially on the throat 

 and flanks. These white blotches (generally on the borderland 

 between the bright brown hair of the upper parts and the whitish- 

 gray of the belly) commonly occur in Scottish otters. On the 

 other hand, in Ireland there is a tendency towards melanism, 

 some specimens of Irish otters being so dark as to be nearly 

 black above and blackish-brown below. 



The number of mammas in the otter is only one pair. The 

 period of gestation is about nine weeks. They only breed once 

 in the year, and the rutting season is in midwinter.^ The young 

 are born either in March or April. They are from two to five 

 in number, and are born blind. The nest in which they are 

 born (which, together with the ordinary retreat of the otter, is 

 called its " holt") is generally a large hole in the bank of a river, 

 under the roots of some overhanging tree or a jutting rock. 



The cry of the otter is a shrill, whistling noise when contented 

 and at play. They also make a whimpering sound, especially 

 when searching for food on land. If alarmed or excited they 

 utter a shrill bark, varied with a whistling call. They have a 

 keen sense of hearing and of smell, but not a good sense of sight. 

 The long vibrissas are extremely sensitive, and no doubt the otter 

 is greatly guided by the sensations transmitted through these long 

 feelers to the nerves of the muzzle. 



The otter, it is needless to say, swims and dives with great 

 facihty, and propels itself with all four limbs, using the tail as a 

 great rudder. It swims in a nearly horizontal position, with the 

 nose just above the surface of the water, unless searching for fish, 

 in which case the otter will swim below the surface, putting up 

 its nose every few minutes to breathe. Although its ordinary 

 habitat in England is large streams or rivers, on the coasts of 



1 It is not certain, however, that breeding may not take place at other 

 seasons of the year, though only one litter of cubs is produced within the 

 twelve months. 



