MIGRATION OF BIRDS. 287 
any locality in Ceylon that there is a good deal of seasonal 
movement, especially among such birds as the smaller species 
of Heron, the Lark family, the Rails, and some of our Hawks. 
We have still to ascertain whether numbers of these birds 
move merely to other parts of the Island during the breeding 
season, or leave our shores for South India. 
It is definitely known that some species—for example, the 
Ashy Finch Lark, Pyrrhulauda grisea, and the Pariah Kite, 
Milvus govinda—which have only a local distribution in 
Ceylon, are largely reinforced during the north-east monsoon 
by migrants from India. I have heard Whistling Teal pass- 
ing over Colombo at night and coming probably from South 
India. 
We have also a small, but very interesting, group of partial 
migrants, which includes the Kentish Plover (Agialitis 
alexandrina), several other species of Waders, and one or two 
of our Terns. The birds of these species which breed with 
us are really resident races of northern migrants, and their 
permanent abode in our Island is probably due to the gradual 
breaking down of the migratory habit. I shall revert to this 
group later on. 
To sum up. Our knowledge of the partial migrants is 
very imperfect, and while in Ceylon this group undoubtedly 
includes a far smaller proportion of the bird population 
than in temperate climates, probably a good deal of partial 
migration passes unsuspected. 
We now turn to a group of non-resident species: the 
stragglers and casual visitors. It is very difficult to draw at 
any one point a hard and fast line of demarcation for these 
two classes. There are about 60 species on the Ceylon list 
which visit us at very infrequent intervals, or which have 
been recorded less than half a dozen times. Some of these 
are genuine waifs, such as the Lesser Scavenger Vulture, 
Neophron ginginianus, of which a stray specimen, probably 
storm-driven from South India, was once obtained at Nuwara 
Eliya. Then there are the ocean wanderers, such as the 
Frigate Birds, Tropic Birds, Boobies, several species of Tern, 
and so on. ‘These turn up at odd intervals, generally after 
stormy weather, and can hardly be classed as seasonal migrants, 
