C U C U L U S. 
436 
ed with lines of black, refembling, 'in fome meafure, the 
eggs of the yellow-hammer. 
“Tile circumfiance of the young cuckoo’s being de¬ 
fined by nature to throw out the young hedge-fparrows, 
feems to account for the parent cuckoo’s dropping her 
egg in the nefts of birds fo fmall as thole I have particu¬ 
larized. If (he were to do this in the neft of a-bird 
which produced a large egg, and conlequently a large 
neftling, the young cuckoo would probably find an in- 
furmountable difficulty in folely polfefiing the neft, as its 
exertions would be unequal to the labour of turning out 
the young birds. Befides, though many of the larger 
birds might have fed the neftling cuckoo very properly, 
had it been committed to their charge, yet they could 
not have fuffered their own young to have been facrificed 
for the accommodation of the cuckoo in fuch great 
number as the fmaller ones, which are fo much more 
abundant; for, though it would be a vain attempt to 
calculate the numbers of neftlings deftroyed by means of 
the cuckoo, yet the flighted obfervation would be fuffi- 
cient to convince us that they muft be very large.” 
It appears a little extraordinary, that two cuckoos’ 
eggs lhould ever be depofited in the fame neft, as the 
young one produced from one of them muft inevitably 
perifti; yet two inftances of this kind fell under the au¬ 
thor’s obfervation, one of which he thus relates : “Two 
cuckoos and a hedge-fparrow were hatched in the fame 
neft this morning, June 27, 1787, when one hedge-fpar- 
row’s egg remained unhatched. In a few hours after, a 
conteft began between the cuckoos for the poffeftion of 
the neft, which continued undetermined till the next af¬ 
ternoon, when one of them, which was fomewhat fupe- 
rior in (ize, turned out the other, together with the 
young hedge-fparrow and the unhatched egg. This 
conteft was very remarkable. The combatants alter¬ 
nately appeared to have the advantage, as each carried 
the other leveral times nearly to the top of the neft, and 
then funk do-vn again, opprelfed by the weight of its 
burden ; till at length, after various efforts, the ftrongeft 
prevailed, and was afterwards brought up by the hedge- 
fparrows.” 
But the principal circumftance that has agitated the 
mind of the natural!ft refpefling the cuckoo is, why, 
like other birds, it lhould not build a neft, incubate its 
eggs, and rear its own young? There is no apparent 
reafon, Mr. Jenner thinks, why this bird, in common 
with others, fhould not perform all tliefe feveral offices ; 
for it is, in every refpeci, perfectly formed for colleiSi- 
ing materials, and building a neft. Neither its external 
ill ape, nor internal dm 61 ure, prevent it from incubation; 
nor is it by any means incapacitated from bringing food to 
its young. It would be needlefs to enumerate the vari¬ 
ous opinions of authors on this fubjefl, from Ariftotle 
to the prefent time. Thofe of the ancients appear to be 
either vifionary or erroneous ; and the attempts of the 
moderns towards its inveftigation have been confined 
within very narrow limits ; for they have gone but little 
further in their refearches than to examine the conftitu- 
tion and ftrubture of the bird ; and, having found it pof- 
feffed of a capacious ftomach, with a thin external co¬ 
vering, concluded that the preffure upon this part, in a 
fitting pofture, prevented incubation. They have not 
coniiaered, that many of the birds which incubate have 
ftomachs analogous to thofe of cuckoos. The ftomach 
of the owl, for example, is proportionably capacious, 
and is almoft as thinly covered with external integu¬ 
ments. Nor have they confidered, that the ftomachs of 
neftlings are always much diftended with food ; and that 
this very part, during the whole time of their confine¬ 
ment to the neft, fupports, in a great degree, the weight 
of the whole body : whereas, in a fitting bird, it is not 
nearly fo much preffed upon, for the bread, in that cafe, 
fills up chiefly the cavity of the neft; for which pur- 
pofe, from its natural convexity, it isadmirably well fitted. 
Thefe observations may be fufficient to fhew, that the 
cuckoo is not rendered incapable of fitting through any; 
peculiarity either in the fituation or formation of the 
ftomach ; yet, as a proof ftill more decifive, our obferver 
adduces the following fact : “ In the fumnter of 178a, 
I faw, in the neft of a hedge-fparrow, a cuckoo, which,, 
from its fize and plumage, appeared to be nearly a fort¬ 
night old. On lifting it up in the neft, I obferved two 
hedge-fparrow’s eggs under it. At firft I fuppofed them 
part of the number, which had been fat upon by the 
hedge-fparrow with the cuckoo’s egg, and that they had 
become addle, as birds frequently fuft'er fuch eggs to re¬ 
main in their nefts with their young ; but,, on breaking 
one of them, I found it contained a living foetus ; fo 
that of courfe thefe eggs muft have been laid fome time 
after the cuckoo was hatched ; as the latter now com¬ 
pletely filled up the neft, and was, by this peculiar inci¬ 
dent, performing the part of a fitting-bird. At this 
time I was unacquainted with the facl:, that the young 
cuckoo turned out the eggs of the hedge-fparrow ; but, 
it is reafonable to conclude, that it had loft the difpofi- 
tion for doing this when thefe eggs were depofited in the 
neft. Having, under my infpection, in another hedge- 
fparrow’s neft, a young cuckoo, about the fame fize as 
the former, I procured two wagtail’s eggs, which had 
been fat upon a few days, and had them immediately 
conveyed to the fpot, and placed under the cuckoo. On 
the ninth day after ihe eggs had been in this fituation, 
the perfon appointed to fuperintend the neft (as it was 
fome diftance from the place of my refidence) came to 
inform me that the wagtails were hatched. On going 
to the place, and examining the neft, I found nothing in it 
but the cuckoo, and the (hells of the wagtail’s eggs. 
The fa6t, therefore, of the birds being hatched, I do 
not give as coming immediately under my own eye ; but 
the teftimony of the perfon appointed to watch the neft 
was corroborated by that of another witnefs.” 
In confidering to what caufes may be attributed the 
Angularities of the cuckoo, Mr. Jenner fuggefts the fol¬ 
lowing as the mod probable : “ The fnort refidence this 
bird is allowed to make in the country where it is def- 
tined to propagate its fpecies, and the call that nature 
has upon it, during that (hort refidence, to produce a nu¬ 
merous progeny.” The cuckoo’s firft appearance here 
is about the middle of April. Its egg is not ready for 
incubation till fome weeks after its arrival, feldom be¬ 
fore the middle of May. A fortnight is taken up by 
the fitting-bird in hatching the egg. The young bird 
generally continues three weeks in the neft before it 
flies, and the fofter-parents feed it more than five weeks 
after this period ; fo that, if a cuckoo fhould be ready 
with an egg much fooner than the time pointed out, not 
a fingle neftling, even one of the earlieft, would be fit to 
provide for itfelf before its parent would be inftinifively 
diredted to (eek a new refidence, and be thus compelled 
to abandon its young one ; for old cuckoos take their 
final leave of this country the firft week in July. Had 
nature allowed the cuckoo to have (laid here as long as 
fome other migrating birds, which produce a fingle fet of 
young ones (as the fwift or nightingale for example), 
and had allowed her to have reared as large a number, 
as any bird is capable of bringing up at one time, thefe 
might not have been fufficient to have anfwered her pur¬ 
pose ; but, by fending the cuckoo from one neft to ano¬ 
ther, (lie is reduced to the fame (late as the bird whofe 
neft we daily rob of an egg, in which cafe, the ftimulus 
for incubation is fufpended. Of this we have a familiar 
example in the common domeftic fowl. That the cuckoo 
abtually lays a great number of eggs, diffe6fion feems to 
prove very decifively. Upon acomparifon, I had an op¬ 
portunity of making, between the ovarium, or racemus vi- 
tellorum, of a female cuckoo, killed juft as (lie had be¬ 
gun to lay, and of a pullet, killed in the fame (fate, no 
effential difference appeared. The uterus of each con- 
tainedanegg, perfe6U-y formed, and ready for exclufion ; 
and the ovarium exhibited a large clufter of eggs, graa 
dually 
