on ihe Diiration of the Period of Incubation. 159


Crows, plenty of information respecting tlie duration of incu¬

bation would be available for the information of bird-keepers,

yet even the late Lord Lilford, who bred the Raven in captivity,

appears to have overlooked the importance of this part of its

life-history:* As these birds do not lay regularly, observations

on the incubation of their eggs are doubtless not easily made ;

but from what Major Bendire says of the N. American species,

there can be no doubt that twenty-one days represent the general

period of hatching for the genus Corvus. Dr. Russ was unable

to give any information on this point.


Judging by what Major Bendire tells us of Clarke’s

Nutcracker, the genus Nucifraga probably incubates for sixteen or

seventeen days. The Chinese Blue Magpi e (Cyanopotius) hatches

out in nineteen daj^s according to Dybowski (vide Russ, “FreindL

Weiclifutterfresser,” p. 695) : this species was bred in our

Zoological Gardens in 1884 and 1888. In Pica incubation seems

to last from sixteen to eighteen days (Bendire, Life-histories of

N. Am. Birds, Vol. II. p. 354). The incubation of the species of

Perisoreus seems not to have been studied, and I can find no

notes as to Garrulus ; but Cyanocitta incubates about sixteen

days according to Major Bendire’s records of the various species.

Respecting Urocissa, Cissa, Dendrocitta, and Ptilostovms I have

no notes. Lady Nevill’s Choughs laid but did not sit well; so

that she was unable to give us information respecting the

incubation of that group of Crows.


Of the Crow-Shrikes and Piping Crows no species appears

hitherto to have brought up a family in captivity, though Baron

von Comely had a pair of pinioned Piping Crows which built

a large nest in the open at Tours; unfortunately both birds were

killed by a polecat before any eggs were laid : and Campbell in

his splendid work tells us nothing as to the incubation of

their eggs.


Of the Larks hardly anything has been recorded to throw

light upon the duration of the brood (‘ Brutdaiter ’ as the Germans

tersely put it) : all we know is from Bendire’s note on Otocorys

alpestris —“incubation, which lasts about fourteen days.” In the



* Mr. St. Quintin (Avic. Mag. n. S. Vol. IT. p. 292) was unfortunately unable to settle

this point in the case of his Ravens.



