XLY. 



GENUS THALASSEUS (Bate). 



ri^HREE distinct species of this genus are found in Australia, the type of which in Europe is 

 J- T. Cantiacus, and which is there widely diffused. 



THALASSEUS CEISTATUS. 



TORRES STRAITS TERN. Gents: Thalasseus. 



CiOMETIMES called the Yellow-billed Tern, this is the most shy and timid of the family, and 

 cannot, like so many of its congeners, be captured with a hook and line, the presence of which, 

 floating on the water, is a signal for immediate flight to a considerable distance. 



This is the largest of all the Terns inhabiting the islands of Torres Straits, where great 

 numbers may be seen at all seasons of the year ; it was considered by Gould to be identical with 

 Sterna Pelecanoides, described by Captain King. 



In mode of life generally this Tern does not differ from Thalasseus Poliocercus (inhabiting the 

 coasts of New South Wales, Victoria and Tasmania), to which it is very nearly allied ; the plumage 

 of the two species is very much alike, but T. Cristaius may always be recognised by the much 

 larger bill and stouter body. 



About the islands of Torres Straits and the low sandbanks of the Great Barrier Reef this 

 species is very numerous. Breeding places were discovered by Mr. Macgillivray on Lizard Island 

 and Raine's Islet. At the latter place the nursery was visited in June, when both eggs and young 

 birds were procured ; here, it was noticed, the birds were divided into three flocks, each having a 

 separate nursery, but all situated on a low ridge on the lee side of the island. As soon as Mr. 

 Macgillivray 's party approached within fifty yards the utmost alarm prevailed among the birds, all 

 those sitting on nests rising and flying away, but returning in a few minutes, they hovered about, 

 anxiously watching the movements of the visitors. The nests were merely slight hollows scooped out 

 of the soft sandy soil, but each was situated in a clear sheltered spot among the scrubby herbage. 

 One egg or one young bird only was found in each nest, and the former varied considerably in their 

 markings: the ground colour of most was a dull grey, in some instances very thickly blotched or speckled 

 with black : others were marked with wavy streaks and small spots of brown ; others again were 

 marked all over with irregular blotches of black, and a great many were noticed in which the larger 

 end was either blotched or streaked with dark red on a light pinkish-grey ground. 



There is no outward difference between the sexes when fully grown ; the young birds, however, 

 may he distinguished by the black part of the head being mottled with white. 



Crown of the head and occipital crest, black ; forehead, sides and back of the neck and all the 

 under surface, silky-grey ; back, wings and tail, ashy-grey, deepening into brown on the edges and tips of 

 the primaries : bill, pale greenish yellow : legs and feet, black. 



Habitats : The islands of Torres Straits and the northern and western coasts of Australia. 



