Birds of Passage

Manawatu Times, Volume 66, Issue 106, 6 May 1941, Page 7

Birds of Passage

Few things in animal life are more interesting than the regular appearance at certain dates every year of certain species of birds on British shores, and their somewhat less regular disappearance after a few months. For long naturalists puzzled over the reason of the migration, though it is due to simple causes. To quote an extract from “Letters of Rusticus”: “Migration is the simplest thing in the world. At certain periods of the year the proper food of certain Bpecies of birds fails in native countries of those species; this is the ‘cause’ of migration; then the first ‘law’ of migration is the ‘instinctive,’ and perhaps in some instances experimental, knowledge that proper food is about to fail. I “The next important facts are that the great mass of birds of passage are j insect eaters; and secondly, that insects at the approach of winter disappear j first from the most northerly countries; if water birds or waders still the facts obtain, the freezing of lakes, rivers, and mudbanks first occurs in the higher latitudes; lienee the second Jaw, that ‘migration is in a southerly direction.’ “Thus migration begins in the autumn, and goes on till winter, keeping pace with the failure of certain I kinds of food. No sooner does spring ' return and promise abundance of food than all the feathered tribes return uorthward to dwell and to rear their young in the very places where they themselves were reared. Come from Different Countries “The country of all species is not the same; thus fieldfares and redwings bred in Scandinavia return to Scandinavia, j and because they feed on hips and haws they go just as far south as to procure | a supply. The ring-ouzel breeds in Carnarvonshire, Derbyshire, Yorkshire, 1 and Lancashire, but not finding sufficient food there, nor yet in our southern countries, nor yet even in France | or Spain, all of which it crosses, it goes on into the warmer regions of Africa.” This explains a large part of the socret of migration—search for food. [ln illustration has been mentioned tha ring-ouzel. These birds in their autumnal flight southwards halt on the Surrey hills and at other places for a space of a month in order to feed on the whortleberries, just then at their best, and when that food fails them they resume their travels southward. The number of British birds, if taken at about 361, includes 63 summer and 48 winter visitors, while 140 are-per-manent residents, and no fewer than 110 capricious visitors. The numbers profess only to bo approximately accurate. It is convenient, and at the same time probably correct, to hold that the natural home of a bird is where it makes its nest and rears its young. It is with this undeustanding that all ! migration or leaving of home is said to be in a southerly direction. Possibly no migration ever takes place north of the nesting place. It is, however, somewhat arbitrary when a bird habitually spends seven months of its year in one place and five in another to speak of its homo being in either.