Vol. VI, 



1 From Magazines, &c. 33 



The nests consisted of great piles of small angular stones. The 

 first eggs were found on the 4th of November. Average length, 

 10.38- cm., and breadth, 6.57 cm. Two per cent, of these birds 

 were pure white. The eggs of the Cape Petrel were a " first 

 discovery," familiar though the bird is. Dr. Pirie took the first 

 eggs on 2nd December, 1902, from nests composed of a few 

 small angular fragments of rock and a little earth placed on 

 open cliff ledges on Laurie Island. Only one egg is laid. 

 Specimens average 62.35 ^ 43.1 1 mm. The eggs are pure white, 

 and large for the size of the bird. The position of the nest 

 varies from that adopted by Kerguelen Island birds of this 

 species, which lay in burrows and grottos. Five hundred Ant- 

 arctic Great Skuas spend the summer on Laurie Island. The 

 first eggs were laid on 2nd December. The nests were hollows 

 in moss on top of rocks or in the earth on moraine tops, and in 

 that case lined with lichens. Two eggs formed the clutch. 

 Two types of bird, a light and a dark, were noted ; in one case a 

 mated pair consisted of one of each type. 



Correspondence. 



PRINCIPLES OF MIGRATION. 



To the Editors of " The Emu." 



Sirs,— It is pleasing to find that the publication of my 

 hypotheses regarding " The Principles Governing .... 

 Migration of Birds" {The Emu, vol. v., p. 147), has brought 

 such a keen observer as Mr. J. Douglas Ogilby into the sphere 

 of controversy — controversy that can but be beneficial, especially 

 if Mr. Ogilby can prove his " hard, incontestable fact " that 

 " home sickness " and the consequent tragedy of " suicide " are 

 the sole concomitants of migration. 



It is here necessary to quote in full my contention, as cited in 

 The Emic : — " Then, again, an analogous case is the migration 

 of birds, in which climatic conditions, apart from food and other 

 conditions, bring about the unfavourable stimulus or stimuli 

 from which the birds move to places where the stimuli are 

 absent or modified. Were there no seasons in the year, birds 

 would remain in the one place, and would lose their migratory 

 habits, provided other unfavourable stimuli were absent. Hence 

 we find the permanent stimuli of the seasons and their reflex 

 actions causing migration always at the same season of the 

 year, and mostly in the same direction, the date of migration 

 varying according to the climatic condition of the season. This 

 leads one to the supposition that migratory birds are of a 

 delicate constitution, which, for their survival, causes them to 

 shrink from the rigorous climatic conditions that cause unfavour- 

 able stimuli and travel to suitable zones," 



