DISPERSAL OF ANIMALS 399 



animals have penetrated to new districts. Several causes 

 have led to this gradual migration. The scraps of food 

 dropped from carriage windows, the grease used in lubricating 

 the railway points and the axles of carriages and trucks, and 

 the grain and other edible stuffs spilt at goods' sidings and 

 stations have induced birds, such as Rooks and Sparrows, and 

 rodents, like Rats and Mice, to follow the permanent way in 

 search of food. The Sparrow has made a tardy appearance 

 at Corrour in western Inverness-shire along the railway route, 

 and is now fairly common at the station there, from which 

 centre, at an altitude of 1350 feet, it is at present in process 

 of colonizing the immediate neighbourhood. About 1910, 

 Dr Eagle Clarke has recorded, it found its way to the Lodge 

 and the neighbouring premises, and has become common 

 there, although in 1917 it had not yet reached the farmhouse 

 and its outbuildings at the head of Loch Treig. Travellers 

 by the Highland Railway over the ridge of the Grampians 

 may see the same hardy campfollower of domestication in 

 numbers at Dalnaspidal, the highest station, close on 1 300 feet 

 above sea level, in the heart of the H ighland moors. 



Less venturesome birds than the Rook and Sparrow have 

 made use of railways in another way. In the centres of highly 

 cultivated areas, railway embankments and the bottoms of 

 hedgerows are almost the only places which otter protection 

 to wild flowers of many kinds and afford them opportunity 

 for ripening their seeds. The railway embankments, there- 

 fore, offer special attractions not only to the seed-eating birds 

 but to insects also, and thus to the insect-feeders amongst 

 birds. Species which, in the first instance, have visited the 

 embankment to feed, have remained to nest, and so pro- 

 nounced has the preference become in some cases, that the 

 embankment has come to be the predominant nesting-place of 

 the Tree Pipits and Pied Wagtails of a district. This tend- 

 ency has made for the dispersal in new areas, of embank- 

 ment-nesting birds, for the birds find not only a protected 

 nesting-place in a natural granary, but a safe roost on the 

 telegraph wires overhead. 



