q8 Alexander, White-ivingcd Black Terns in W.A. [,st oot. 



not know whether the unusual numbers of this common dragon- 

 fly were reared in Western AustraUa or whether they also had 

 migrated into the district. In this connection I may mention 

 that enormous numbers of the butterfly Danaida chrysippus 

 petilia appeared in south-west Australia in the summer of 

 1914-15. This species usually visits the area each summer, but 

 in that year its numbers were incredible to anyone who did not 

 see them, and it was accompanied by Terias smilax, which had 

 never been met with in the south-west before, as well as by 

 Anaphcvis iara teutonia and Papilio demoleus sthenelus. This is 

 not the place to enlarge on this insect migration, but it is worth 

 noting that the visitation of Terns can be paralleled by similar 

 irruptions of insects. 



In these days many people attribute any unusual occurrence 

 to the war, and it has been seriously suggested to me that the 

 birds had been disturbed from their haunts on the Danube or 

 the Tigris by the fighting in those areas, and were seeking a 

 peaceful home in Australia. 



During the weeks following .Easter the birds remained plentiful 

 in the neighbourhood of Perth, and I frequently saw them about 

 the Swan River. On two occasions I visited Herdsman's Lake, 

 a large swamp a few miles from Perth, with Mr. T. P. Draper, 

 in order to obtain specimens for the Museum. 



The flock on Herdsman's Lake consisted of several hundred 

 individuals, and, as already described, they spent their time 

 hovering with widely-spread tails over the water and reeds 

 capturing dragon-flies. Towards afternoon they settled down to 

 rest among the reeds, and those that remained flying about were 

 chiefly immature birds. I imagine that the older birds, being 

 more adept at catching dragon-flies, obtained all the food they 

 required by mid-day, whilst the young birds continued feeding 

 longer. A slightly larger Tern of a different species, which I think 

 was a Marsh Tern {Hydrochelidon hyhrida), was associated with 

 the birds on Herdsman's Lake, but it was not secured for 

 identification. 



Four different states of plumage were represented— 



(i) Adult in full breeding plumage. — Less than i per cent, were 

 in this plumage, and no specimen was secured, bat, as already 

 mentioned, one was seen by Mr. Lipfert. I saw one or two whose 

 bodies appeared to be entirely black on Herdsman's Lake, and in 

 the first week in May I had an excellent view of one sitting on a 

 post in the Swan River at Perth. In this plumage the head and 

 body are completely black, the wings grey, with a small white 

 patch on the shoulder, the tail pure white. The feet and legs 

 red, the bill black. This is the only feature in which this bird 

 and the one seen by Mr. Lipfert differed from the illustration 

 given by Mathews and the descriptions in the books. Is the red 

 beak the last featiu'e of the breeding coloration to be assumed, 

 or does the Eastern form of the species have a black bill instead 

 of a red one ? 



