36 



ORNITHOLOGIST 



[Vol. 10-No. 3 



well therefore in the course of our remarks on 

 migration, if we advance gradiiallj', considering 

 tii'st the simple cases, which present no ditticultj'. 

 It is obvious that some birds are alwajs resident 

 in this country, such as the Sparrow, wliicli sup- 

 plies its wants the whole year round in the neigh- 

 borhood of our homesteads. Some of these resi- 

 dents are wanderers — in fact, every bird is a 

 wanderer more or less when it shifts its quarters 



daring the year in seeking food 



The experimental flights of birds for the sake of 

 discovering nesting places, food, or some other 

 object, must not be regarded as either vagrant or 

 mysterious; for whatever name may attach to 

 such excursions, they belong to a kind of migra- 

 tion which is constantly occurring. They may 

 be compared, perliaps, to the rambles of gipsies, 

 wlio set up their tents wherever they can find a 

 vacant spot by the roadside, or perhaps they may 

 lie more accurately likened to the extension of a 

 fir forest, whidi literally marches up the slopes ot 

 a Scotch hill and occupies new ground by the 

 scattering of its seeds. By such accidents, by 

 wandering and migration in the case of man and 

 other animals, and by an analagous seizure of new 

 sites in the case of vegetables, the world has been 

 peopled and planted. 



In his work on the "Distribution of Plants and 

 Annuals," Jlr. Wallace remarks tbat migration in 

 its simple form may be best studied in North 

 America, where it takes place over a continuous 

 land surface with changes of climate North and 

 South. We have there every grade of migration, 

 from that of species which merely shift the 

 northern and southern limits of their range a few 

 liundred miles to that of some other species 

 wliicli move over l,()t)0 miles of latitude and are 

 birds of passage in all the intervening districts. 

 Some have extended their range under conditions 

 favorable to them and induced by human agency, 

 such as the Rice Bird and the Mexican Swallow, 

 and we may be sure that in all parts of the world 

 the range of birds has always extended under 

 favoring conditions of one kind or another. The 

 cultivatlcm of fresh tracts of land will bring such 

 liu'ds as follows the plough into new districts, and 

 the presence of an advancing bird population will 

 carry the individuals comi)Osing it into all parts 

 where life can be sustained. As the birds in- 

 crease in any district they naturally wander 

 farther, for the same reason that man himself 

 emigrates from an over-crowded country. There 

 is of course a distinction between migration and 

 distribution, but when migrating birds become 

 more widely distributed from any cause the 

 range of their Jiiigration must necessarily be 

 exteude<l. So far as the initial motive is con- 



cerned all migrations are similar, though thej' 

 differ widely in their extent and in the circum- 

 stances that attend them Natural- 

 ists have drawn distinctions between difi'erenl 

 kinds of migration, which they have classified as 

 those of Spring, when our Summer migrants arrive, 

 departing again after breeding, and those of Au- 

 tumn, by birds that winter here and depart from 

 our shores in the Spring. The birds of passage, 

 as they are called, which pass through a country 

 without remaining long, are bent on exactly the 

 same business as the true migrants. They are 

 simpl3' passing to their quarters. A Fieldfare 

 prefers England to the Arctic circle in Winter, 

 and comes here accordingly, and if he rests on 

 Heligoland, he is there a bird of passage. In 

 Spring he returns perhaps. A bird of jiassage 

 may breed in the north or south; he may pass 

 the particular spot where he is observed as a bird 

 of passage in Autumn or in Spring; his migration 

 may be long or short ; he is at the end of his two 

 journeys a true migrant, like the Swallow, or like 

 those sweet Warblers in our groves and hedges 

 which disappear entirelj- at their season, while 

 the partial migrants. Pied-wagtails, Woodcocks, 

 Snipes and others, do not entirely leave u.s. The 

 Song Thrush and Robin are among the birds 

 which as species remain always with us, but the 

 number of individuals of all these kinds is in- 

 creased by migration in Spring and Autumn more 

 extensively than casual observers might imagine. 

 The Redbreasts though they do not flock at the 

 end of Summer, pass constantly southwards^ 

 prompted by their migratory instincts, and do 

 not stop at the Channel. Another movement of 

 a migratory character on the i)art of the same 

 familiar birds, is that which brings them to our . 

 homesteads on the ajiproach of seveie weather. 

 This is not migration in the ordinary sense, and 

 it offers no problem hard to solve, but the short 

 journeys are undertaken with the same objects as 

 the long ones, and they may serve as illustrations 

 of the first promptings of the instinct of migra- 

 tion. The flight from wood and fiehl otters no 

 difficulty; it is guided evidently by sight and 

 memory of former fliltings; or perliaps some of 

 the inexperienced birds may wander hither and 

 thither for a while seeking the shelter and fooil 

 they need, finding it haphazard or failing to do so 

 and perishing in their search. The long flights 

 f)f Cranes and other strong-winged birds have 

 formed the subject of theories still wilder than 

 the flights perhaps, and arising from the in- 

 sufficiency of the facts relating to them. The 

 argument should be inductive. The short flit- 

 tings perhaps will be found to explain the longer, 

 and thus the mystery may be found to rest on 

 simple causes after all. 



