Evening Republican, Volume 19, Number 123, Rensselaer, Jasper County, 25 May 1915 — The MIGRATION of BIRDS [ARTICLE+ILLUSTRATION]

The MIGRATION of BIRDS

by A.W.Douglas

" EW facts in natural bisfory are so fi interesting as the annual mlgra* tlon of birds, and largely because *|gL there is such little real underlsl?f..> II standing as to the nature and {Man w U methods of this remarkable phei. ■ -j o nomenon. Theories are plentiful, but a demonstrable explanation of all the facts involved is still wanting. Some of the Inherent characteristics of migration, such as the apparent sense of direction possessed by birds, seem to defy observation and analysis, and to be absolutely beyond our ken so far as any understanding goes. The. cause itself of this curious habit so fscr is only conjectural, but the most logical explanation seems fco be a search for food. This apparently bolds good for the fall flight from North to South, when insects have perished from the cold, and vegetation died, so that both Insectivorous and grain-eating birds are alike affected. Yet some members of both species, crows, Jays, quail, * partridges, wood ducks, cardinal grosbeaks (the ordinary red bird) and often some red-beaded woodpeckers, remain North throughout the win- - ter and manage somehow to make a living and * their species. Even if these be exceptions to the general rule, tbere still remains the unanswered question, Why do not those birds who winter in the South remain there throughout the year instead of going North when the spring opens? Food is abundant and apparently southern latitudes are as fitting for the rearing of young as the far North/ As a matter of fact, we really do not know, though we have some interesting and-plausible theories about it that do not bear the test of questioning. So as usual when we run across some mystery in animal life that we cannot unravel, we call it “Instipct,” and let It go at that Of this one tjiing we may, however, be quite sure, that instinct in anfmals always Berves some useful purpose, and is usually an expression of nature’s care for the preservation of the species. Years of observation have developed the interesting fact that there are certain wfill-deflned routes in all countries which the migrations follow, certain water courses, certain chains of mountains, certain valleys, and this seems to obtain from one generation of birds to another. Whether the younger birds learn this from the older birds who have been before, or whether they simply mechanically follow the older birds in their flights is largely conjecture, but two facts seem well established. First, that animals evidently have some method of communicating with each other. Everyone who has heard *Bob White call together the scattered covey, or the hen give the alarm for a hawk to her chickens, is convinced on this point. The second fact seems, however, to controvert the theory of the older teaching the younger ones the way they should go, for it has been shown in many Instances that flocks composed entirely of the year’s broods .«f young birds make their first migratory flight alone and unattended by the older birds, and find their way unerringly along the usual routes of migration. Once more we have to fall back upon instinct. Just how birds find their way from one distant .latitude to another is the most inexplicable of all the many mysterious facts of migration. The length of the flight from northern habitat to winter resort varies according to the k different species of birds all the way from 1,000 | to 3,000 miles, and In a few casfes to 6,000 miles. * Yet these distances are apparently traversed In generally direct straight lines, and with the. most orderly and businesslike methods of procedure. To say that the older birds show the younger birds the way (since this has been shown to be -untrue in many cases) only removes the difficulty back into the remote past, for at some time there had to be some birds to find the way the first time, and we only this difficulty when we talk of inherited instinct. It is clearly not a case of birds seeing their way and being guided by landmarks. It is known that migrations as a rule take place at night, and that In general birds fly very high, in fact, at tremendous heights, when migrating. Under such conditions finding their way by sight is impossible. Moreover, the sight theory breaks down in the case of those birds who cross great •stretches of water where there are no landmarks whatever. There is a species of cuckoo which summers in New, Zealand and winters In eastern Australia, which Means a straight flight of some 1,100 miles without, rest or stop across the track-less-Waters. Certain species of humming birds that^"winter in Central and South-America spend their summer vacation Jh the United States, and to do so must fly across some 1,000 miles of the Golf of Mexico. A recent experiment demonstrated that neither •the theory or seeing the way nor previous knowledge of the route can account for the finding of the way in migration. Fifteen terns were taken from their nesting places on Bird Key, Tortngas (one of die islands of the Florida reef) and were released at distances varying from 20 to 850 from their home, and 13 of the 16 found their way back safely. Observations have also •hown that the same birds return to the same spot year after year. -Robins that winter in Florida will build their nests in the same tree 1s t northern state u long Hve ' FoaMsskm ot' ,

tiod —concerning whose physical basis and nature we are-entirely in the dark. It seems to be a eysnse common to most animals. It is extremely weil developed In horses and dogs, and likewise in fishes, who year after year come back to the same stream to spawn. It la possessed a lesser degree by man, being more pronounced In the savage than In the civilized man, probably because In the latter disuse has dulled its perception. The speed' at which- birds fly during migration probably varies according to the natural capacity of the species. Nevertheless, In such flights

they display a speed and endurance entirely out of their ordinary wont. A little sandpiper, which summers in northern Siberia near tlje Arctic, has to fly over the Himalaya mountains in order to reach India, where it passes the winter. In doing this it must vise to heights of four miles and- upwards to clear the towering ranges. Wilson’s petrel Is known to range from the South Antarctic ocean to the northern limits of British America. As ducks and geese are almost the only birds whose migrations have been seen In the daytime, many telescopic observations and instantaneous photographs have been taken of them during flight.-'These observations indicate that the flight of ducks, particularly teal, must frequently reach a speed of 100 miles an hour and over. Even with the slower flying birds It Is possible to cover long stretches in one night, as the flight seems to be pursued without rest “all throught the night" The probable choice of night for flight is that the day may be devoted to feeding. Besides, the dangers of the birds of prey, other than owls, are thus avoided. The ducks that reach this latitude In the spring are frequently very thin and poor, evidently owing to the strenuousness of their voyage. One of the remarkable characteristics of migration is the regularity of its annual movement among the different species, often the same day each fall and spring marking the departure and arrival. The flights seem invariably to be in flocks, whether the species be gregarious or otherwise. No sooner is the destination reached than the nongregarious species separate either singly or in pairs. One exception to this are robins, which are nongregarious In the North, but invariably- go In flocks In the South. Jusl why some birds of the same species stop in one latitude while others go farther on Is not known, though probably the question of food supply is the determining factor. The whole subject of migration is one of the interesting phenomena in nature which has been a matter of common observation for some thousand years and yet of whose essential nature we have only the scantest Information.