68 THE TERNS 



3. Migration. A summer visitor. The earliest arrivals are seen on our 

 shores towards the end of March. The dates of first arrivals recorded by the 

 watcher at Ravenglass for 1907, 1908, 1909 were respectively 28th, 27th, and 29th 

 March. In Scotland the first records are generally for the beginning of May. 

 In Ireland a March arrival is rather the rule than the exception. For a long list of 

 records see Ussher and Warren, Birds of Ireland, p. 317. The dates of departure 

 are not well known. By the 23rd of July in 1909 the birds had all left Ravenglass 

 (cf. British Birds, iii. 170). On August 20 of the same year, a young bird of the 

 year ringed at Ravenglass in June was captured thirty to forty miles north of 

 that place, thus tending to show that the southward movement is not general in 

 August (op. cit., p. 181). On the Yorkshire coast birds are seen moving south in 

 August, but small parties remain till September and even October (Nelson, Birds 

 of Yorks., p. 652). They reach the Kent coast about the end of September, 

 and stay only a few days before going south (cf. Ticehurst, B. of Kent, p. 499). 

 [A. L. T.] 



4. Nest and Eggs. This species breeds in colonies on sandy flats, often 

 with a scanty growth of plants, and in many cases the nests are mere hollows 

 scratched in the sand, though occasionally fairly substantial nests of bents and 

 dead vegetable matter cast up by the sea may be met with. Its nests may also 

 be found on shingle, on mudbanks, and in sea-campion (see p. 102). (PL xm.) 

 The eggs as a rule are 2 in number, and clutches of 3 are quite excep- 

 tional in most colonies, though occasionally a small group may contain two or 

 three such nests. On one occasion 4 eggs were found in a nest, but it is very 

 doubtful whether they were all laid by one bird. They are remarkably hand- 

 some and show considerable variation, the ground-colour ranging from greyish 

 or creamy white to warm stone colour, sometimes suffused with brown. The 

 markings consist of spits and blotches of dark sepia or rich red-brown exceptionally, 

 varying in size and sometimes forming a zone, while in some eggs they are almost 

 absent, or replaced by fine specks. The underlying markings are ashy bluish or pale 

 brownish, and in some eggs are very prominent, consisting of large blotches. (PL H.) 

 Average size of 100 eggs, 2-03xT42 in. [51-7x36-1 mm.]. Incubation begins as 

 soon as the first egg is laid, and, according to Mr. F. G. Paynter's observations, lasts 

 for 20 days (Naumann gives three weeks as the period). Both sexes share in the 

 work (see p. 103). Like the other terns, in fine weather they leave their eggs exposed 

 to the sun for long periods. The breeding season is decidedly earlier than that of 

 the other British species, and eggs may occasionally be found at the end of the first 



