28 SPOLIA ZEYLANICA. 



number of years and in every part of the Island. Incidentally, 

 I may mention that the collecting of such material will 

 probably bring out some very interesting facts on the internal 

 migration of certain species from one part of the Island to the 

 other. 



As it will be a long time before the full materials can ever 

 be collected, I am going to be rash enough to give you this 

 evening some tentative speculations on the causes which 

 govern the continuance or the variation of the breeding 

 seasons of different species in the same district. These 

 speculations are based on my own collection of eggs, and on 

 my rather fragmentary observations. 



I may state at the outset that my collection consists of about 

 80 species, the majority of which have been taken in the 

 North-Central Province and the Tangalla district of the 

 Southern Province. Accordingly, my remarks must be taken 

 as applying only to these two districts, or at all events, only 

 to the dry low-country zone to which both belong. The 

 rainfall and climatic conditions of the two areas present no 

 marked differences, and I should say that over 90 per cent, 

 of the species of birds inhabiting the one region are to be found 

 in the other. 



As I said above we have no real seasonal changes in Ceylon, 

 and the birds breed whenever the climatic conditions are most 

 favourable. At breeding-time birds must have an ample food 

 supply, and what I may term a suitable environment for their 

 nests ; the meaning of the latter phrase will appear more fully 

 as I go along. 



Now, any climatic conditions which will give birds these two 

 requirements will induce them to breed in greater or less 

 numbers, and, broadly speaking, these conditions are fulfilled 

 during, or soon after, any period of rain, but the conditions 

 vary for different classes of birds. 



In both Tangalla and the North-Central Province the rainy 

 season begins at the change of the south-west to the north-east 

 monsoon, and the rains extend roughly from October to 

 Christmas. There are, more or less, frequent showers from 

 Christmas onwards till the burst of the south-west mdnsoon, 

 but February, March, and April are often dry, and are 



