Is the PintailecL Whydah Parasitic ?



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IS THE PINTAILED WHYDAH PARASITIC?


By Dr. A. G. Butler.


In the “Journal of the South African Ornithologists’

Union,” 2nd ser., vol I., pp. 9-11, is an article by Mr. Austin

Roberts, in which he attempts to prove that Vidua principalis ,

instead of building a nest for itself and incubating its own eggs,

substitutes them, after the manner of a Cowbird, for the eggs of

Waxbills and leaves them for the latter to rear.


Mr. Roberts first got this idea into his mind from hearing

that, according to the Zulus, a young Vidua principalis is reared

out of every nest of Estrilda astrilda. Subsequently the discovery

of two sizes of eggs in Waxbill’s nests, a difference in one of five

fledglings in a Common Waxbill’s nest, and lastly the fact that

he observed a hen Pintailed Whydah leaving a nest of this

species, in the passage of which he found a half-devoured egg,

and in the cavity one egg larger than the others, convinced him

that he had obtained the true explanation of the difficulty of

discovering the nest of the Pintailed Whydah.


So much for the evidence in favour of parasitism. On the

other hand the late Dr. Stark described nests of V. principalis

very minutely, and says that all those which he found contained

3 7 oung birds; and, as Mr. Roberts admits, “ without the least

doubt as to the identity of the nests and the young birds.”


Stark indeed says that “ the eggs are not yet described,”

and this statement opens the way for the conclusion at which Mr.

Roberts arrives, that the larger eggs in the nests of Waxbills

belong to the Whydah. If so, we must conclude that, like

Hypochera and unlike other Whydahs, this species lays a white

unspotted egg; but Captain Shelley tells us unhesitatingly:—

“The egg is glossy greyish white, with underlying violet marks

and clear black or dark brown elongated surface-marks, evenly

distributed. It measures o - 6S x o'5C.” As with Dr. Stark, his

description is given without the least doubt as to the identity of

the egg.


When a typical Whydali’s nest has been described—“ the

ends of the growing grass being tied together over the nest”



