Red-breasted Starlings, etc.



151



I should be glad if other members of our Society who have

kept Oryzoborus could give us some definite information respect¬

ing its behaviour in captivity, whether it really is destitute of

both call-note and song and whether it does despise mealworms

or other insects. It seems inconceivable that any finch should

be entirely non-insectivorous: I believe that even those Grass-

finches which feed upon seed only in their normal condition, eat

aphides when rearing their young—if they can get them.



RED-BREASTED STARLINGS, ETC.


By Dr. A. G. Buti/er.


The theory of protective assimilation is doubtless well

known to the more scientific members of our Society; but, for

the benefit of those not acquainted with it, I may briefly sum¬

marize it as follows :—


It is believed that some animals owe their very existence

to the fact that, at some stage of their development, they pro¬

duced certain varieties which tended to resemble more favoured

species ; that is to say, species which were powerful enough to

defend themselves, were immune from destruction because of

their offensive odour, or some other unpleasantness; or to the

fact that their form or colouring rendered them difficult to dis¬

tinguish from their surroundings. This tendency in the desired

direction having been, to a slight extent, protective, some of

these slight variations survived to perpetuate the new type, which

gradually improved in its resemblance until eventually it became

almost perfect: the harmless and tasty creature was passed over

in mistake for the dangerous and offensive one, or because of its

close resemblance to its natural surroundings.


That the truth of this state of things is borne out in many

instances throughout the animal kingdom cannot be questioned :

one of the most striking instances of environmental protection

being seen in the case of the Weavers of the genus Pyromelana y

the females of which are always protected by their Sedge-

Warbler-like colouring, rendering them inconspicuous among

reeds or coarse grasses, while the male only assumes his mar¬

vellously showy dress during the breeding-season, at a time when.



