454 THE DIVERS 



estimate of the pace attained by the bird when swimming on the 

 surface and also when diving. The former he computed at four and 

 a half miles per hour, and the latter at between six and seven 

 miles, while the distance covered at each dive was about eighty to 

 ninety yards. When diving for food, however, P. H. Bahr estimated 

 the immersion period at about one and a half minutes. 



Like the other Divers, in bright sunny weather it will roll over on 

 its side and enjoy the warmth of the sunshine on its breast, slowly 

 revolving in the meantime owing to the fact that one foot only is in 

 action. When diving it has been known to use its wings occasionally. 

 Thus Saxby surprised one in a burn and chased it for two hundred 

 yards, the whole of which space was traversed without taking breath. 

 He distinctly saw that the bird was " flying " under water, not merely 

 paddling with its wings as it does sometimes when feeding. 1 

 O. V. Aplin also notes that one observed by him diving against a 

 strong current, made considerable use of its wings. It is a more 

 sociable bird than the blackthroat, and is rarely seen alone. Collett 

 describes a breeding-place on the islet of Store Tamso in the 

 Porsanger fjord. Here, on a pond only a couple of gun-shots across, 

 he saw on 3rd July 1872 fifteen nests with eggs. In 1876 he again 

 visited the spot, but the young were already hatched off, and he 

 estimated the number of breeding pairs on the island at about thirty. 

 Another smaller colony of about ten pairs was found by Thome in the 

 Trondhjems fjord. During the early summer of 1912 I came across a 

 similar colony in south-west Iceland. Some large, flat, grass-covered 

 islands stood in the middle of a wide river, the banks rising some 

 two feet above the water. Redthroated-divers were to be seen in 

 pairs flying overhead with weird cries, while little fleets of half a 

 dozen birds sailed quietly on the river, sipping unconcernedly at the 

 water from time to time. The farmer who owned the islands had 

 collected no fewer than fourteen clutches on the previous day from 

 this colony, but even this did not exhaust the supply, for we saw two 



1 Birds of Shetland, p. 282. 



