DISCOVERY 



45 



I have elsewhere ^ drawn attention to our extraor- 

 dinan,- ignorance regarding the habits of many even of 

 our common birds. Isolated facts are something, but 

 systematic obser%-ation and thought, systematic about 

 what one observes, are needed to lighten the darkness. 



The obser\-ations here recorded were made in Spits- 

 bergen on the Oxford University Expedition in July 

 of last year. The photographs accompanying the 

 article are incidental only, for, alas ! it was impossible 

 to secure photographs of any of the courtship activities, 

 as these take place on open water away from the nest. 

 I ha\-e therefore had to supplement them with thumb- 

 nail sketches, which I think are better than no 

 illustration at all. 



The Red-throated Diver presents a particular 

 instance of a problem which has long exercised me. 

 In the Divers, as in the Grebes, the Herons, the Cranes, 

 and many other birds, both sexes are alike, and both 

 brightly coloured ; and, as we shall see later, the bright 

 colours are used in courtship. \Mien one sex only has 

 special ornaments, be they of colour, structure, scent, 

 or voice, we can fall back upon some modification of 

 Darwin's famous theory of sexual selection. In such 

 case, the ornaments of one sex are an assistance to 

 successful mating ; for the members of the other sex 

 exercise some sort of discrimination, and are not equally 

 pleased or stimulated by all cock birds. Thus there is 

 a growth of ornament in one sex which is detennined 

 in the long run by the " taste," if we may use the word 

 in a somewhat metaphorical sense, of the other sex. 

 The theor\- has had to be modified in various minor 

 respects, but its main principle holds firm : that the 

 female needs stimulating, that stimulation is provided 

 by the beautiful and by the strange in the male, and 

 that therefore the mind of the female exerts a selective 

 influence in evolution over these special male characters. 



What, however, are we to make of the facts when 

 both sexes have bright colours, or special structures, 

 like the Grebe's ruff or the Egret's plumes, which all 

 analog\' would lead us to suppose were used in court- 

 ship ? 



The puzzle is still far from being completely solved. 

 But my previous obser\-ations on the Crested Grebe 

 and various Herons and Egrets, like those of Edmund 

 Selons on Grebes, Guillemots, Fulmars, and other birds, 

 have at least led to two perfectly straightforward 

 results. In such cases the bright colours and special 

 structures are used in courtship (using that word in an 

 extended sense to cover all ceremonies based upon the 

 sexual emotion) ; and they are almost always used 

 by both sexes in equal degrees. The habits of the 

 Diver corroborate these results. 



The terrain of my observations was the eastern edge 

 of Prince Charles Eoreland, a sixty-mile island off the 



1 Proc. Zool. Society, 1914 ; The Auk, 191.5. 



west coast of Spitsbergen. Between the central 

 mountain backbone and the sea there extended a 

 comparatively flat strip of land, a mile or so in width, 

 with small scattered lochs — the nesting-places of the 

 Divers. Close to our camp there was also a large 

 brackish-water lagoon, about five miles in length, 

 separated from the sea only by a narrow spit of shingle ; 

 here the birds often came to rest and to fish. 



In this latitude the Divers have a ver\' short season 

 in which to bring off their \-oung. WTien we arrived, 

 on June 30, 'the little lochs were aU quite, or almost 

 quite, frozen over, and nesting was out of the question ; 

 and September brings the rapid autumn. It is there- 

 fore imperative for the birds to start nesting as soon 

 as they can ; that they do so is shown by the fact that 

 I found a nest with one egg only seven days after the 

 first sign of thaw in one loch, another nest with the 

 complete complement of two eggs eight davs after the 



THE RED-THROATED DIVER ON ITS KEST. 



beginning of the thaw in another loch. The first nest 

 was within three or four yards of a snow-bank. 



In passing, some of the curious methods of pro- 

 gression of the bird may be noted. The nest is always 

 somewhat raised to protect the eggs from possible 

 floods, and is often at some yards' distance from the 

 water. When the water is verj- shallow, the Divers 

 progress by their well-known but none the less extra- 

 ordinary method of resting their breast on the ground-, 

 and then giving a great kick with their legs so as to 

 propel the whole body upwards and forwards, the 

 breast coming down again with a bump. In this 

 action, the hind-quarters are disproportionately raised 

 and the motion is like that of a very clumsy rabbit 

 slowh' moving forward. When there is a stretch of 

 dry land to cover, the bird may walk erect ; but it 

 can only advance a few yards at a time in this way, 

 dropping down to rest for a little before trying the 

 erect posture once more. I say " erect posture," but 

 it is a travesty of the erect posture that the bird adopts. 

 The legs are placed so far back that the body leans a 



