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Dr. A. G. Butler,



THE BALANCE OF NATURE.


By Dr. A. G. Butler.


Last winter, owing to its length and severity, w© all had to

deplore great mortality in wild birds, and in the spring adult birds

appear to have been unusually scarce in some parts of the country,

although I cannot say that I noticed much difference in this

neighbourhood ; still, it is likely enough that in the suburbs of any

great city birds would be able to get more shelter and food than in open

and unreclaimed land.


The question is — need we anticipate a scarcity of birds for

some time to come in consequence of last winter’s losses ? I think

not, and for several reasons. It is probable that the strongest

individuals were able to survive, and to these would be added the

examples which had been impelled to migrate southwards by the

cold, and which, by the reduced competition for nesting-sites, would

probably remain with us.


In the second place, inasmuch as cold has comparatively little

effect in reducing insect life, the scarcity of birds at the season

when many insects were waking from their winter sleep, or emerging

from the pupa, would certainly tend to make the latter unusually

abundant; many thousands which, in ordinary seasons would be

devoured, would survive to lay their eggs ; and thus an unusual

quantity of food would be provided with which insectivorous birds

could readily feed their young.


The abundance of caterpillars and white butterflies this year

has been noticed by all agriculturists and gardeners, and children

have been employed in some places to catch butterflies; but it is to

be hoped that they have been instructed only to destroy the injurious

white species, and not the beautiful insects whose caterpillars feed

on noxious weeds, grasses, wild violets, or leaves of shrubs and trees.

On the other hand, the caterpillars of many moths are perfect pests.


"When insect-food is scarce, either few young will be reared,

or those which are brought up will probably be delicate and short¬

lived : in captivity, when sufficient insect-food cannot be provided,

the parents either throw some of their young out of the nest,

or else all perish from weakness. This year there can have been



