THE GULL-BILLED TERN. 697 



especially that of middle toe. Bill stout and deep, gonys rather 

 sharply sloped up from angle which is fairly prominent, tip of lower 

 mandible sharply pointed but that of upper more obtuse. Nostrils 

 basal and slit -like. 



Soft farts. — Bill black; legs and feet (ad.) black, (juv. and 

 1st winter) dark red-brown ; iris black-brown. 



Characters and allied forms. — G. n. macrotarsa (Australia) is 

 larger and has almost white upper -parts ; other forms have been 

 separated on slight differences in bill. Stout, black bill distinguishes 

 this from other British Terns. 



Breeding-habits. — Breeds in colonies, nests placed close together, 

 on shores of shallow lakes, lagoons, etc. Nest.— Hollow in sand or 

 earth, scantily lined with grass, sea-weed or any kind of drifted 

 vegetation. Eggs. — Normally 3, sometimes 2 only and 4 have been 

 recorded : ground-colour, ochreous to creamy-whitish or brownish, 

 spotted rather sparingly, with brown, ranging from sienna to sepia 

 and small ashy -grey shellmarks. Average of 100 eggs, 49.3x35.4. 

 Max.: 54.5x33.2 and 50.1x40.1. Min. : 43x33.5 and 49.2x32.1 

 mm. Breeding -season. — About 2nd or 3rd week May onward in 

 south Europe, exceptionally end April : end May and early June in 

 Denmark. Incubation. — No reliable details available. Single brooded. 



Food. — Varied, including frogs, tadpoles, etc., young of other shore- 

 breeding birds as well as eggs, lizards, mice, Crustacea (small crabs), 

 small fish, and insects. Latter class includes coleoptera (esp. 

 Melolontha), orthoptera (locusts and grasshoppers), lepidoptera, 

 odonata, etc. 



Distribution. — Great Britain. — Very rare vagrant. About twenty- 

 eight : Lanes (two), Yorks (one), Norfolk (ten), Kent (four or five), 

 Sussex (six), Hants (one), Devon (one), Cornwall (one), Scilly (one), 

 Pentland Skerries, Orkney (one). All spring or summer. 



Distribution. — Abroad. — Breeds in Europe on coasts of Jutland, 

 formerly on small island near Riigen in Baltic and Schleswig, 

 exceptionally in Bavaria, Hungary (apparently now only one 

 breeding-place), south France, Spain, and Portugal, Greece, Asia 

 Minor, on Black and Caspian Seas, and north-west Africa (island on 

 Tunisian coast, Algeria). Across temperate Asia to Mongolia, 

 Persia, and Punjab (India). In winter, in north and east Africa and 

 tropical Asia south to Sunda Is., Banda and Luang, once Australia. 

 Replaced in nesting areas by closely allied forms in south-east China, 

 Australia, N. and S. America. 



Genus HYDROPROGNE Kaup 



Hydkoprogne Kaup, Skizz. Entw.-Gesch. unci Nat. Syst., p 91 (1829 

 — Type according to diagnosis and by subsequent designation by Gray, 1846, 

 S. caspia). 



Largest Terns with long, strong, red bill, chiefly characterized 

 by their short tail which is only about one -third of length of wing, 



