CHAPTER XI
SUMMARY
Migration owes its origin to the potentiality of flight, enabling birds to advantage themselves by extended dispersals, which through heredity become instinctive, regular and periodical. Geological changes, especially the passing away of the glacial epoch, only influenced by opening up new lands for summer colonisation, but climatic conditions prevented these lands from becoming permanent abodes and fostered the habit of periodical migration. Whatever the original home or centre of distribution may have been, the dispersal from it was towards new lands with a retreat towards the food-supply when these lands became untenable. Fluctuating food-supply, love of home, sexual impulses, desire for light, varying temperature, and other factors, all have more or less influence, but the force exerted by any or all depends upon the species operated upon and the locality in which it resides. The present route followed or method of migration is little guide to the history of past migration; during the evolution of present-day migration alterations may have been occasioned by environment and changing conditions. As Seebohm puts it, "The desire to migrate is a hereditary impulse, to which the descendants of migratory birds are subject--a force almost, if not quite, as irresistible as the hereditary impulse to breed in the spring" (44).
The route is simply the course followed between the breeding area and winter quarters; it is more or less restricted by the size of the area in which food is to be found; it is usually the most direct way from one food-base to the next, in a general direction from the seasonal bases. Most birds move between north and south, but migrations are regularly followed in other directions by some species.
Routes may follow coast-lines, these providing visible landmarks, and also, for many species, plentiful food; islands, capes, estuaries and inlets are landmarks, asylums, food-bases, and sites for congregation and departure for cross-sea passages; at these places migration is often specially noticeable. Overland routes may suggest "broad front" migration, when there are no particular restricting influences and the species have no special need for hurry. Migration at great elevations and at high rates of speed is proved, but the highest and quickest possible is as yet unascertained. It may also, under other conditions, be performed at low elevations and very slowly. It is probable that strong air-currents at a high elevation materially assist rapid and lengthened migration. Force not direction of wind influences birds moving at a low elevation.
Birds possess a certain power of orientation, a homing instinct, which need not be called a sixth sense. Brain and eyes assist in the development of this power; birds have an excellent memory. Young birds lose their way more frequently than is generally supposed; variations in routes are explained in many cases by these errors. Young may or may not be guided by experienced adults; orientation is not infallible but develops with age.
There is apparently no truth in the assertion that birds travel by choice against a head wind or in a beam wind; a moderate wind behind, on which they are carried, is most favourable. Leeward drift through contrary winds explains many normal and abnormal routes, and the occurrence of unexpected species in unexpected places. The distance travelled not only varies according to species but in individuals of the same species; the thesis that the most northerly breeder winters farthest south does not always hold good.
Much may be learnt by the careful registration of arrivals and departures of migratory birds, and by the marking of birds. Ornithophænology, the science of migration study, as carried on at present in many countries, would be materially assisted by some better method of international registration and interchange of ideas.
In conclusion I would urge the value of the study, citing Herr Herman's reasons put before the International Ornithological Congress in 1905. The solution of the problem is in the interest of science, and therefore of intellectual progress, teaching us the great part which migratory birds play in the scheme of nature. The millions of birds which wander, season after season, from one zone to another, represent an enormous aggregate of labour, by flight and search for food, acting on "the organic life of nature as does the regulator of a steam-engine, at one time accelerating, at another retarding." Full insight into the essence of the work done by birds will give us a correct notion of their usefulness or injuriousness to man, and lead us to rational action for their protection.
Whilst fully agreeing with Herr Herman I would go further. We live in an age when aerial locomotion has become important, and will be more and more important in the future. Every lesson we can learn from the successes or failures of these most perfect aerial navigators must be of use.
But putting aside economic and utilitarian considerations, there is to some of us a greater stimulus to solve the problems of nature. With the birds, and the insects and plants upon which they feed, we share a common heritage, and the more we learn of the life of these, our fellow workers, the nearer we approach solution of the great riddle of the Universe, the mysterious law-abiding scheme of Nature. The book of knowledge to which we may add some iota is marred with mystery, superstition and error, but each proved fact cleanses its pages. "Facts," says Laing, "are the spokes of the ladder by which we climb from earth to heaven."
* * * * *
BIBLIOGRAPHY
1. ALLEN, J. A. Cooke's _Some New Facts about the Migration of Birds_, _Auk_, xxi., 1904, 501.
2. ---- Gätke's _Heligoland_, _Auk_, xiii., 1896, 137.
3. ---- Walter's _Theories of Bird Migration_, _Auk_, xxv., 1908, 329.
4. BARRINGTON, R. M. "The great rush of Birds, etc." _Irish Nat._, xx., 1911, 97.
5. ---- _The Migration of Birds as observed at Irish Lighthouses and Lightships_, London, 1900.
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7. BREHM, C. L. "Der Zug der Vögel," _Isis_, 1828, _Naumannia_, 1855.
8. BREWSTER, W. "Bird Migration." _Mem. Nuttall Orn. Club_ Cambridge, Mass. No. 1, 1886.
9. BROOKS, W. K. _The Foundations of Zoology_, New York, 1899.
10. _Bulletin of the British Ornithologists' Club. Reports on Migration_, vols. xvii., xx., xxii., xxiv., xxvi., 1906-1910.
11. CARPENTER, F. W. "An Astronomical Determination of the Heights of Birds," _Auk_, xxiii., 1906, 210.
12. CHAPMAN, ABEL. _Bird-Life of the Borders_, 2nd edit., London 1907.
13. ---- F. M. "Observations on the Nocturnal Migration of Birds," _Auk_, 1888, 37.
14. CLARKE, A. H. "The Migration of Certain Shore Birds," _Auk_, xxii., 1905, 134.
15. CLARKE, W. E. "Bird Migration in Great Britain." _Report of the British Association_, _London_, 1896.
16. ---- "Studies in Bird Migration," _Ibis_, 1902, 246, 1903, 112.
17. CLARKE, W. E. "The Birds of Fair Island; Native and Migratory." _Ann. Scot. Nat. Hist._, 1906, 4.
18. COOKE, W. W. "Distribution and Migration of North American Shorebirds." _U.S. Dept. Agric. Biol. Survey_, Bull, 35, Washington, 1910.
19. ---- "Routes of Bird Migration," _Auk_, xxii., 1905, 1.
20. ---- "Some New Facts about the Migration of Birds." _U.S. Dept. Agric. Year Book_, 1903, 371.
21. ---- "Our Greatest Travellers." _Nat. Geog. Mag._, 1911, 346.
22. ---- "The Migratory Movements of Birds in Relation to the Weather." _U.S. Dept. Agric. Year Book_, 1910, 379.
23. CORDEAUX, J. "Migration in the Humber District," _Zool._, 1892, 418.
24. DERHAM, W. _Physico-Theology_, London. 1737. Lect. delivered in 1711-12.
25. DIXON, C. _The Migration of Birds_, London, 1892.
26. ---- _The Migration of British Birds_, London, 1895.
27. FREDERICK II., (Emperor). _De Arte Venandi cum Avibus_, Ed. Schneider, 1788, (Rhea. ii.. 1849).
28. GADOW, H. F. "Migration," _Encyclo. Brit._, 11th Edit., Cambridge, 1911.
29. GÄTKE, H. _Heligoland as an Ornithological Observatory_, Trns. Rosenstock. London, 1895.
30. HERMAN, O. "A.M.O.K. Ornithophænologiæ anyaja," _Aquila_, 13, 1906, xx.
31. ---- _Recensio Critica automatica of the Doctrine of Bird-Migration_, Budapest, 1905.
32. LAIDLAW, T. G. "Reports on the Movements and Occurrences of Birds in Scotland during 1902 and 1903." _Ann. Scot. Nat. Hist._, 1903-4.
33. (LEGG, JOHN). _A Discourse on the Emigration of British Birds_, London. 1795. (Salisbury, 1780, and London 1811, the latter under name of George Edwards.)
34. LINNÉ. C. _Dissertatio migratione Avium._ Upsaliae, 1757.
35. MIDDENDORF, A. T. VON. _Die Isepiptesen Russlands Grundlagen zur Erforschung der Zugzeiten und Zugrichtungen der Vögel Russlands_, St Petersburg, 1853.
36. MENZBIER, M. "Die Zugstrassen der Vögel im Europäischen Russland." _Bull de la Soc. Imp. d. Nat._, Moscou, 1886, 291.
37. NEWTON, A. _A Dictionary of Birds_, London, 1893-1896.
38. ---- "Migration," _Encyclo. Brit._, 9th Edit., London.
39. PALMÉN, I. A. _Om foglarnes flyttingsvägar_, Helsingfors, 1874.
40. ---- _Über die Zugstrassen der Vögel_, Leipzig, 1876.
41. SCHÄFER, E. A. "On the Incidence of Daylight as a determining factor in Bird Migration." _Nature_, 1907, 159.
42. SCLATER, W. L. "The Migration of Birds in South Africa." _S. African Orn. Union_, 1906, II., 14.
43. SCOTT, W. E. D. "Some Observations on the Migration of Birds." _Bull. Nuttall Ornith. Club_, vi. 97.
44. SEEBOHM, H. _Geographical Distribution of the Family "Charadriidae,"_ London, 1888.
45. ---- _The Birds of Siberia_, London, 1901.
46. SERVICE, R. "Bird Migration in Solway." _Ann. Scot. Nat. Hist._, 1903, 193.
47. STEBBINS, J. and FATH, E. A. "The use of Astronomical Telescopes in determining the speeds of Migratory birds." _Science_ (New York), xxiv., 1906, 49.
48. STEJNEGER, L. "Do Birds Migrate along their Ancient Immigration Routes." _Condor_, vii., 1905, 36.
49. STONE, W. "Bird Waves and their Graphic Representation," _Auk_, 1891, 194.
50. STUBBS, F. J. "The Use of Wind by Migrating Birds." _Mem. and Proc. Manchester Lit. and Phil. Soc._, vol. 53, 1909.
51. TAVERNER, P. A. "A Discussion of the Origin of Migration," _Auk_, xxi., 1904, 322.
52. TOMISON, J. "Bird Life as observed at Skerryvore Lighthouse." _Ann. Scot. Nat, Hist._, 1907, 20.
53. TRUMBULL, J. "Notes on Land Birds observed in the North Atlantic and the Gulf of St Lawrence." 1904. _Zoologist_, 1905, 293.
54. WALLACE, A. R., _Nature_, x., 1874, 459.
55. WHITLOCK, F. B. _The Migration of Birds_, London, 1897.
In addition numerous notes in the following periodicals have been consulted:--_Annals of Scottish Natural History_, _Auk_, _British Birds_, _Condor_, _Emu_, _Field_, _Ibis_, _Irish Naturalist_, _Naturalist_, _Nature_, _Zoologist_.
INDEX
ALLEN, J. A., 29, 34, 49, 61, 64
American Golden Plover, 24, 61, 77
---- Robin, 102
Anacreon, 114
Anticyclones, 89
Arctic Tern, 3
BAIRD, S. F., 120
Barometric Influence, 88
BARRINGTON, R. M., 108, 109, 111
Beam Wind, 61, 96
Black and White Creeper, 68
Blackbird, 50, 109, 112
Blackheaded Gull, 75
Black Redstart, 109
Black-throated Blue Warbler, 69
Bluethroat, 123
Brambling, 7, 22
BRAY, R. A., 49
BREHM. C. L., 32
BREWSTER, W., 37, 106
BROOKS, W. K., 32, 124
BURROUGHS, J., 56
BUTLER, A. L., 121
Cape Pigeon, 121
CARPENTER, F. W., 48, 49
Chaffinch, 22
CHAPMAN, A., 45, 54
CHAPMAN, F. M., 48, 49
_Charadrius dominicus_, 77
_Charadrius fulvus_, 80
---- _plurialis_, 77
_Chrysomitris tristris_, 48
_Ciconia alba_, 71
CLARKE, A. H., 61
CLARKE, W. E., 6, 9, 38, 51, 59, 61, 64, 84, 85, 87, 88, 89, 94, 95, 100, 107
CLAYTON, H. H., 49
Common Tern, 75
COOKE, W. W., 6, 24, 25, 38, 41, 68, 69, 77, 79, 80, 101, 103, 104
CORDEAUX, J., 96
Corncrake, 117
COUES, E., 12
COX, P., 39
CRAWSHAY, R., 29
Crossbill, 123
Curlew, 8, 25, 111, 122
_Dendroica coerulescens_, 69
DERHAM, W., 116
Dipper, 7
Disasters at lights, 85, 105, 106
DIXON, C., 41, 43, 60, 116
DOCKRAY, J. A., 120
Dunlin, 8, 109
EDWARDS, G., 116
FATH, E. A., 55
Fieldfare, 7, 22
FREDERIC II., 115
GADOW, H. F., 20
GÄTKE, H., 33, 34, 47, 50, 51, 52, 62, 63, 121
GEOFFROY ST HILAIRE, 115
Geographical Distribution, 2, 10
_Geothlypis trichas_, 69
Glacial Epoch, 20
GLAISHER, 90
GMELIN, J. G., 117
Goldcrest, 95, 96, 109, 113
Goldeneye, 25
Golden Plover, 23, 24, 25, 26, 61, 77, 80, 111
Great Auk, 22
Great Crested Grebe, 44
Guillemot, 124
Hawk Owl, 121
HERMAN, O., 5, 6, 38, 40, 99, 115, 118, 129
Hibernation, 115, 116
_Hirundo rustica_, 65
Homer, 114
Hooded Crow, 51, 75, 97
HUDSON, W. H., 28, 124
Hudsonian Godwit, 28, 29
Isepipteses, 39
Jack Snipe, 7
Knot, 3, 28
Labrador Duck, 22
Land-bridges, 42, 43
Lapwing, 23, 74, 85
LEGG, J., 5, 117
Lesser Black-backed Gull, 123
_Limosa haesmastica_, 28
LUCANUS, 47
MACH-BRUER, 61
Manx Shearwater, 122
MAREK, M., 32
MARSHAM family, 117
MARTORELLI, G., 61
Maryland Yellowthroat, 69
Meadow Pipit, 109
MERRIAM, C. H., 6
MIDDENDORF, A. T. Von, 39, 58
_Mnistitta raria_, 68
MÖBIUS, K., 61
MONTAGU, G., 115
Moon-phases, 108
Moult, 67
NEWTON, A., 2, 11, 61
Nightingale, 43
Noddy Tern, 64
Non-breeding birds, 27, 28
_Numenius longirostris_, 122
_Oestrelata brevipes_, 123
---- _neglecta_, 123
Orientation, 56
Ornithophænology, 6, 117
Oystercatcher, 109, 111
Pacific Golden Plover, 26, 80
Pallas's Sand-grouse, 8
Palm Warbler, 69
PALMÉN, I. A., 39
Penguin, 124
Puffin, 124
QUINET, A., 41
_Quiscalus purpureus_, 48
RED GROUSE, 3, 7
Red-throated Diver, 124
Redwing, 22, 88, 109, 111
Ringing, 71-76
Robin, 7, 8, 109
Rook, 8, 97
Rushes, 85, 88
Sanderling, 28
SCLATER, P. L., 10
SCLATER, W. L., 66
SCOTT, W. E. D., 48
SEEBOHM, H., 19, 35, 36, 66, 107, 116, 124
SERVICE, R., 50, 96
Skylark, 109, 113
SMITH, A. C., 117
Snipe, 8, 109
Snow Bunting, 121
Song Thrush, 4, 7, 8, 73, 74, 109, 112
Sooty Tern, 64
Spoonbill, 50
Starling, 17, 109, 112, 113
STEBBINS, J., 49, 55
STONE, W., 112
Stonechat, 109
STUBBS, F. J., 52, 97, 98, 100
Submerged Coastlines, 42
Swallow, 36, 51, 65, 94
Swift, 18
TAVERNER, P. A., 2, 17, 30
TAYLOR, H., 98
Teal, 76
Thomson, A. L., 71
TOMISON, J., 88, 97, 105
Trans-Atlantic Migration, 119
TRISTRAM, Canon, 65
TRUMBULL, J., 121
Tufted Duck, 17
_Turdus migratorius_, 102
Turnstone, 28
Turtle Dove, 17, 44
Upland Goose, 124
VEREY, A. S., 48
WALLACE, A. R., 19, 31
WALTERS, H. E., 64
Water-rail, 109, 117
WATSON, J. B., 64
Wheatear, 67, 68, 109, 121
White Stork, 71
Wild Duck, 109, 111
Wind Pockets, 122
Wind Speed Tables, 92, 93
WINKENWERDE, H. A., 49
Woodcock, 75, 109
Yellow-browed Warbler, 123
Transcriber's Note: Although most printer's errors have been retained, some have been silently corrected. Some spelling and punctuation, capitalization, accents and formatting markup have been normalized. Paragraphs which were split by illustrations, have now been rejoined.