NOTES. 251 



The Sandwich Tern illustrates the protective value of the 

 covering of the eggs by the bird from the time the first is laid, 

 very plainly. The eggs of this species are conspicuous, and 

 I have known as much as a week to elapse between the hatch- 

 ing of the two eggs in a clutch ; if the first laid had not been 

 covered by the bird, the Gulls would have destroyed it long 

 before the seven days had elapsed for the completion of the 

 clutch. Another point worthy of notice is that this species 

 voids the fceces from the nest, and the surrounding " white- 

 wash " draws attention still more strongly to the already 

 conspicuous eggs (see photograph) . The Common and Arctic 

 Terns (the latter also incubates from the deposition of the 

 first egg) have the same habit, but in a much lesser degree. 

 The Little Tern, however, which sometimes depends for the 

 protection of its eggs upon their coloration alone, does not 

 possess this habit, and the same is the case with such species 

 as the Ringed Plover, Oyster-catcher and Lapwing, which 

 rely upon protective coloration for the safety of their eggs. 



Eric B. Dunlop. 

 Referring to the notes on pages 169 and 196 on the above 

 subject, it may be of interest to state that in 1904 I found 

 three perfectly spotless pale-blue eggs of the Black-headed 

 Gull {Larus ridihundus) in one nest on an islet of Lough Mask, 

 CO. Galway, Ireland. 



In the same season I saw two eggs of the Arctic Tern 

 {Sterna macrura) as spotless (and another with only two 

 minute black spots), in nests on the shingle at Killala Bay, 

 CO. Mayo, Ireland. 



The three eggs of the Black-headed Gull were all in one 

 nest : those of the Arctic Tern were in different nests, accom- 

 panied in each case with normally coloured eggs. 



Hugh S. Gladstone. 



[Single blue eggs occur so frequently among most species 

 of terns and gulls as not to be worthy of separate records. 

 In the case of the Black-headed Gulls, clutches of three blue 

 eggs have been found on many occasions, and most large 

 collections of British birds' eggs contain examples of this 

 type. Although the white-grounded eggs with blotches of 

 dark markings almost always show signs of defective shell 

 construction, this is not always, as Mr. Dunlop points out, 

 the case with blue eggs, which at times only lack the surface 

 markings and are otherwise perfect. 



As the habit of sitting on the eggs as soon as laid is common 

 to all colonies of both species, it can have no effect on the 

 presence or absence of these varieties in different colonies 

 of the Black-headed Gull or Common Tern. The appearance 



