GOLDEN AND GREY-PLOVERS 369 



They repeat this with long pauses, especially at sunset, when they are 

 very uneasy, and fly about calling continually late into the night. 

 Occasionally they repeat the call so quickly that it becomes a " Jodel " 

 call. When a couple quarrelled they called loudly " tlju, tlju" l 



In both of these plovers there is a good deal of individual varia- 

 tion in the intensity and distribution of the black acquired on the 

 throat and breast in the breeding season. In two birds of equal age 

 and vigour the males would probably show the richer development of 

 black, but it cannot be taken as a guide as to sex in all pairs. The 

 golden-plovers that nest in the British Isles do not assume so perfect 

 a spring dress as those that nest in more northern climes. In all of 

 the photographs taken by Dr. Heatherley (ante, p. 360) the bird appears 

 to be the same individual. The black area is broken and mottled 

 with light feathers, and is limited to the throat and breast ; there is 

 none on the sides of the head, and very little on the lower part of the 

 neck. The mate of this bird, which appeared after the young were 

 hatched, was said to be richer in black. 2 Mr. Abel Chapman says 

 the Northumbrian birds always have more or less white mixed in 

 with the black, giving them a marbled appearance. 3 There is also 

 often a distinct break between the black of the throat and breast. 

 The rule seems to be, the farther north the richer the development of 

 black. Even in the Shetlands and in Norway there is a decided 

 difference. Of the grey-plover Harvie-Brown and Seebohm state that 

 the males appear to have richer contrast darker breasts and cleaner 

 white over the eye than the females ; but some females are much 

 darker than others, nearly as dark as some males. They also thought 

 that males retained the black longer than the females. 4 Mr. Trevor- 

 Battye described the breasts of all males as being equally dark, whilst 

 the females varied. 5 



1 Dresser, Birds of Europe, vii. p. 461. * Country Life, August 26, 1905. 



3 Bird-life of the Borders, p. 17. Ibis, 1876, p. 222. 



5 Icebound on Kolguev, p. 432. 



