Vol. II. 



I go 



I Le Souef, Birds Changing Colour of Plumage. '99 



itself into a question of evidence) — but in many species of birds a moult 

 does usually (so far as we know) occur as they pass from immature to 

 mature plumage, or from winter to summer dress. 



The problem is a difficult one, and to arrive at a satisfactory conclusion 

 the phases of the change from immature to mature plumage will probably 

 have to be considered apart from the questions involved in seasonal 

 changes, and microscopic research into the structure of living feathers will 

 have to play a large part in the inquiry. Will not some of our workers 

 throw further light on the matter ? The matter must in some phases 

 remain an open question until further knowledge comes. — H. Kendall.] 



Colour Reversion in Kingfishers' Eggs. 



(Plate XL) 

 By Robert Hall. 



{Read be/ore Ihe A us f. O.U., Melbourne Congress, z\st November, 1902.) 

 Many species of birds lay coloured eggs in hidden places, so 

 that light will not be even reflected upon them. The 

 Chthonicola is one of them. Kingfishers' eggs are invariably 

 white, upon our present knowledge, just as Pardalotes' are, both 

 occurring under like circumstances. Yet each family, I find, is 

 subject to reversion. Is one at liberty to use this term, 

 considering the vast period of time since reptiles and primitive 

 birds laid white eggs and then rust-coloured ? The recent find- 

 ing of rust-coloured eggs in three species of Australian King- 

 fishers and one of Pardalotus leads me to think that we are 

 shown cases of reversion — a probable ancestral habit of secret- 

 ing and depositing pigment. The primitive eggs, like those of 

 their cousins, the reptiles, were probably white, as now, but not 

 so highly glazed. The mediaeval eggs were probably partly 

 rust-coloured, as those of the present day Tuatara lizard 

 of New Zealand, for example. The Kingfishers, having 

 left the most probable exposed ground nests of the middle 

 ages, with brown eggs, for protection, now lay white eggs, 

 hidden in hollows. It has been thought that many birds, failing 

 to produce brown eggs, after a long period of " typical whites," 

 sought protection for their eggs in the hollows of trees. The 

 finding of eggs of three species of Kingfishers leads me to go one 

 step apart, and suggest that many birds, nesting in the open, 

 with eggs protectively coloured, sought the hollows of trees for 

 other reasons, and lost the mediaeval brown, and, by reversion, 

 got back to white. Natural selection, effecting a change in the 

 habit of the birds nesting, did away with the necessity of 

 protective colouration. Now we have Kingfishers' eggs revert- 

 ing to the mediaeval phase. This surely is a slow working, but 

 most likely a universal one. 



The Pardalote referred to laid a clutch of deep brown eggs 

 in the hollow of a creek near Kyneton, Victoria. These were 

 extracted with a long spoon by Mr. J. Rigby. A few days 



