MIGRATION. 
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of a bird’s life; its influence is so great as often 
entirely to change the creature’s habits of life. A bird, 
while under this secret influence, is in a constant state of 
restlessness, as though torn by two conflicting desires— 
the wish to depart, and home sickness. To us the “ pas¬ 
sage” is, in many respects, still a wonder and a riddle; 
and, indeed, it seems as though the further we seek to 
explain it the darker and more inexplicable it remains. 
The second class of migration is more imperfect in its 
character than the first. It has no fixed season or 
direction, and does not take place regularly every year, 
but only occasionally, terminating when the cause is 
removed. It consists of abandoning districts where 
means of nourishment are failing, and seeking others 
where food is plentiful; the object fulfilled, the move¬ 
ment ceases; and not unfrequently the immigrants 
attach themselves to the locality and breed there. 
The third and last is mostly dependent on similar 
causes. It is a migration with uncertain, but narrow 
limits: a short flight in search of food, or some more 
eligible spot to dwell in than that already occupied. It 
takes place at all seasons, is the result of accident, and 
occurs all over the world. It may not inaptly be compared 
to the vagrant life of a strolling player. 
When a bird breeds one year in one place and one in 
another, as does, for example, the Crossbill, one may 
call it, to use an expression of my father’s, “ leading the 
life of a gipsy;”* and, in truth, that sort of existence is 
but a limited kind of migration. 
* The reason why the Crossbills select breeding localities in this irregular 
manner is a matter dependent on the presence or absence of certain kinds of 
nourishment. Where fir cones are plentiful, the Common Crossbill is found in 
abundance, and but few of the Parrot Crossbill; while where the pine is common, 
the Parrot Crossbill predominates.— W. J. 
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