Cuckoo. ZYGODACTYLI. CUCULUS. 99 
sen. ‘Taking advantage of the absence of its dupe, during 
the time of laying (which generally occupies four or five days), Peculiari- 
the cuckoo deposites its egg among the rest, abandoning it, woe uae 
from that moment, to the care of the foster-parent. As the 
same period of incubation is common to both birds, the eges 
are hatched nearly together, which no sooner takes place, 
than the young cuckoo proceeds instinctively to eject its young 
companions, and any remaining eggs, from the nest. 'To ef- 
fect this object, it contrives to work itself under its burden 
(the back, at this early age, being provided with a peculiar 
depression between the shoulders), and shuffling backwards 
to the edge of the nest, by a jirk rids itself of the imcum- 
brance; and this operation is repeated, till the whole beng 
thrown over, it remains sole possessor. ‘This particular ten- 
dency prevails for about twelve days, after which the hollow 
space between the shoulders is filled up ; and when prevented 
from accomplishing its purpose till the expiration of that time, 
as if conscious of inability, it suffers its companions to remain 
unmolested. The égg of the cuckoo is very small in propor- 
tion to the size of the bird,-which circumstance is in close 
connection with the instinct, that directs it to choose for its 
“depository the nest of a smaller species. If it selected that 
of a larger bird, the offspring that its young one would have 
to contend with, being its equal, perhaps its superior, in size 
and weight, would consequently frustrate the design, and the 
young cuckoo would perish in the vain endeavour at the sole 
possession of the nest. It is an opmion very commonly en- 
tertamed, that this bird sucks the other eggs in the nest, 
where it deposites its own, but there appears to be no reason 
for supposing this to be the case; the belief has, without 
doubt, arisen from the fact of the young cuckoo being so 
often found sole tenant, after the expulsion of its copartners. 
It has been suggested by Montacu, and I should think, 
with great probability, that the cuckoo may possess the power 
of retaining its egg in the ovoduct at pleasure, otherwise it 
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