The nest being of great size is a very conspicuous object; it is composed of sticks varying from the size of a finger to that of the wrist, and lined with the softer kinds of sea-weed. It is usually placed on the summit of a rock, but is sometimes constructed on the top of a large _Eucalyptus_; always in the vicinity of water. A nest observed by Mr. Gilbert in Rottnest Island measured fifteen feet in circumference. The eggs are two in number, of a yellowish white, boldly spotted and blotched with deep rich reddish brown, which colour in some specimens is so dark as to be nearly black; other specimens again are clouded with large blotches of purple, which appear as if beneath the surface of the shell. The medium length of the eggs is two inches and five lines, and the breadth one inch and nine lines.
When near the water its flight is heavy and flapping, but when soaring aloft at a great altitude its actions are the most easy and graceful imaginable, at one moment appearing motionless, and at another performing a series of beautiful curves and circles, apparently for mere enjoyment; for from the great height at which they are executed it is hardly to be conceived that the bird can be watching the motions of its finny prey in the waters beneath.
Crown of the head, back of the neck, throat, abdomen, thighs and under tail-coverts white; feathers of the chest mottled with brown, and with a dark brown mark down the centre; ear-coverts and sides of the neck dark brown; back, wings and tail clove brown, each feather of the back with a narrow circle of white at its extremity; primaries black; bill black; cere and base of the bill bluish lead-colour; feet pale bluish white; irides primrose-yellow in some, bright orange in others; claws black.
The figure is about two-thirds of the natural size.
_J. Gould and H. C. Richter del et lith._ _Hullmandel & Walton Imp._ ]
_Falco hypoleucus_, Gould in Proc. of Zool. Soc., Part VIII. p. 162.
_Boorh-ga_, Aborigines of Moore’s River in Western Australia.
Of this rare and beautiful Falcon I have seen only four examples, three of which are in my own collection, and the fourth in that of the Earl of Derby. The specimen from which my description in the “Proceedings of the Zoological Society” was taken, was presented to Mr. Gilbert by Mr. L. Burgess, who stated that he had killed it over the mountains, about sixty miles from Swan River; subsequently it was obtained by Mr. Gilbert himself in the vicinity of Moore’s River in Western Australia; and my friend Captain Sturt had the good fortune to secure a male and a female during his late adventurous journey into the interior of South Australia. “They were shot at the Depôt on a Sunday in May 1845, just after service; they had been soaring very high, but at length one descended to the trees on the creek, and coming within range was shot; when the other proceeding to look after its companion was also killed. It must be a scarce bird, for no others were seen.”