THE BIRDS OF AUSTRALIA. 
sufficient to cles»r natural obstacles — ^and wlien flying they carry their legs 
extended straight out under the tail, shifting them, still extended, to a right 
angle with the body to regulate the balance upon any sudden turn becoming 
necessaiy, on the sighting of a desired lizard or grasshopper. They are 
handsome-plumaged birds, spotted above, while the under-surface of the wings 
iooks like mother-of-pearl. Though the bulrush beds are their favourite 
haunt, they also hunt the open downs.” 
North, in the Austf, M.us. Spec. Co/t., no. 1, Vol. Ill,, 1911, p. 177, records 
notes from various observers, but these mainly relate to nests and eggs alone. 
As regards habits Bennett had informed him : Cifcus assimilis is in these 
parts (near Booligal, N.S.W.) of migratory habits, usually arriving about 
the end of August and departing again, after breeding, about February. 
It frequents the plains and open country^ being rarely found in thick 
timber, and it preys chiefly upon small reptiles and such birds as Quail, 
liUrks, etc., to which is added large insects such as grasshoppers and 
Mantis.” 
Macgillivray noted : “ Examples of Circus assimilis may often be seen 
sailing and flapping their way slowly over the plains in search of food. On 
the wing they are easily distinguished from their congeners by the general 
light grey colour, and when seen from underneath, the black tips of the wings 
serves stiU further to distinguish them.” There is a note from Keartland 
regarding their boldness in attacking rabbits and ferrets. North also notes 
that in the Australian Museum collection there are specimens obtained by 
Mr. George Masters at King George’s Sound, West Australia. Shortridge 
also noted, as recorded by Ogilvie-Grant, Ibis 1910, p. 171, that : The 
Allied Harrier does not appear to be confined to swampy situations, as it was 
observed in the central and western divisions as well as on Bernier Island, 
It is probably less numerous than Circus gouJdi in the south-western 
division.” 
What the South-western birds are like I am unable to decide, but those 
from the North-western I separated subspecifically, and the characters of that 
form seem to be fairly constant. I state this as so far my experience has 
been that nearly all the members of this Order are variable, and while a few 
specimens can be easily determined, a larger number makes subspecies very 
uncertain quantities. The differences in size between the sexes, the plumage- 
changes and the time these take, and the continual moult, all serve to 
complicate the attempted separation of these birds into subspecies until the 
personal equation becomes omnipresent. 
According to my examination the birds from Celebes and the northern 
islands differ in their very slatey-blue backs and throats, and upper chest with 
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