60



Evidence afforded by Captive Birds.



fact of partial confinement does not entirely obliterate a bird’s

preferences in the matter of food.


There is a tendency in the minds of exclusively indoor Zoolo¬

gists to decry the value of the work done by aviarists and curators of

Zoological Gardens : they assert that the animals observed being'

more or less limited to a comparatively small area, do not behave as

they would in a wild state, and consequently all observations

recorded must he wholly untrustworthy. Do birds in an aviary

alter their entire method of nidification ? As a rule we know

that they do not ; and when they do, it is because reason shows them

that some other method is more advantageous under existing circum¬

stances : indeed, as I have previously stated, centuries of cage life

have not obliterated from the minds of the Bengalee and Canary

the pattern of the nest which their remote ancestors used to build

when at liberty, and in an aviary containing shrubs these birds

construct their typical nests to-day.


Of course, in order to ascertain the favourite food of any wild

animal an examination of the stomachs of numerous free examples

is by far the better way ; but nevertheless a study of the evident

preferences shown in captivity is not altogether valueless. All

evidence should be accepted with caution, and the testimony of many

workers in various lands should be carefully studied and thought

over before any conclusions are come to, and it should always be

borne in mind that “ Natura non facit saltum ” is a rule rarely

broken and the development of so-called mimetic forms must have

been an exceedingly slow process, much more so than if insectivorous

animals actually cared a brass farthing what colour was presented to

them, or what attitude a caterpillar assumed when at rest or

startled. Brightly coloured caterpillars are generally severely pecked

even when subsequently rejected, so that their coloration does not

preserve life unless it puts birds upon their guard against interfering

with similarly coloured examples ; to some extent it may be so,

though I am inclined to think that smell is a more potent deterrent

than any arrangement of colours, and undoubtedly some brightly-

coloured caterpillars are rejected by certain birds, though not by all,

because they are hairy.; yet the perfect insects evolved from them



