INTRODUCTION OF BIRDS. 19 
industry is, in a variety of ways, destructive even to tribes not 
directly warred upon by man.* 
Nature sets bounds to the disproportionate increase of birds, 
while at the same time, by the multitude of their resources, she 
secures them from extinction through her own spontaneous 
agencies. Man both preys upon them and wantonly destroys 
* LYELL, Antiquity of Man, p. 409, observes: ‘‘Of birds it is estimated 
that the number of those which die every year equals the aggregate number 
by which the species to which they respectively belong is, on the average, 
permanently represented.” 
A remarkable instance of the influence of new circumstances upon birds was 
observed upon the establishment of a light-house on Cape Cod some years 
since. The morning after the lamps were lighted for the first time, more 
than a hundred dead birds of several different species, chiefly water-fowl, 
were found at the foot of the tower. They had been killed in the course of 
the night by flying against the thick glass or grating of the lantern. 
From an article by A. Esquiros, in the Revwe des Deux Mondes for Sept. 1, 
1864, entitled, La vie Anglaise, p. 119, it appears that such occurrences as 
that stated in the note have been not unfrequent on the British coast, Are 
the birds thus attracted by new lights, flocks in migration ? 
Migrating birds, whether for greater security from eagles, hawks, and other 
enemies, or for some unknown reason, perform a great part of their annual 
journeys by night; and it is observed in the Alps that they follow the high 
roads in their passage across the mountains, This is partly because the food 
in search of which they must sometimes descend is principally found near the 
roads. It is, however, not altogether for the sake of consorting with man, 
or of profiting by his labors, that their line of flight conforms to the paths he 
has traced, but rather because the great roads are carried through the natural 
depressions in the chain, and hence the birds can cross the summit by these 
routes without rising toa height where at the seasons of migration the cold 
would be excessive. 
The instinct which guides migratory birds in their course is not in all cases 
infallible, and it seems to be confounded by changes in the condition of the 
surface. Iam familiar with a village in New England, at the junction of two 
valleys, each drained by a mill-stream, where the flocks of wild geese which 
formerly passed, every spring and autumn, were very frequently lost, as it 
as popularly phrased, and I have often heard their screams in the night as 
they flew wildly about in perplexity as to the proper course. Perhaps the vil- 
lage lights embarrassed them, or perhaps the constant changes in the face of 
the country, from the clearings then going on, introduced into the landscape 
features not according with the ideal map handed down in the anserine family, 
and thus deranged its traditional geography. 
