56 RUDOLF SÖDERBERG, STUDIES OF THE BIRDS IN NORTH WEST AUSTRALIA. 
making all the plumage here very spotted in comparison with the more uniform 
brown back of the adults. 
This kite was not common or seemed to appear rather sporadically. For its 
occurrence cf. the former species. 
Elanus axillaris GouLp. 
Math. handl. n:r 271. SI ad. St. Georges Range ?/3 1911. 
Very seldom seen in the districts the Expedition visited. 
Falco lunulatus LATH. 
S juv., 2 ad., 8 juv. Nooncanbah, Fitzroy r. 6/12 1910, new plumage, ?/1 1911; 2/1 1911; 2 ad. 
Meda, Kimb. 3/5 1911, faded plumage; 2 29 ad. Beagle bay, Dampier land 19/7, 4/8 1911, faded plumage. 
Juvenal. — Very broad rufous edges on the back and chestnut-rufous on the 
sides of the neck and on the small wing-coverts (Plate 1, fig. 3). 
Variants. — The phenomena of discoloration that I have often observed 
in the plumages of the birds in the dryest season in Kimberley prevailed in a very 
conspicuous manner in the May, July and August specimens of this species. In the 
spec. of the 4th of Aug. the intense sunlight had caused a change of the whole 
upper-side, which from ashy blue had turned dark sooty brown to such an extent 
that the original colour had totally vanished. If we compare it with the specimen 
of the 8th of Jan., which has just obtained a new blue plumage by moulting, we 
have an instance of the effect of these bleaching phenomena. It has happened 
even to the breast, which has lost its strong chestnut colour. Fig. 1, 2 and 3, 
plate 1, show, in addition to the changes of colour, the most interesting differences 
between the plumage of the juvenal and that of the adult. 
Ecological. — I have observed this falcon on several occasions in Beagle bay. 
It did not appear until the day drew to a close. Then I saw it chasing the bats 
that wére flying about over the tops of the trees in the darkness. One specimen, 
that was cut open, had recently eaten two of these animals. 
It was not common and was not found at Sunday Island. 
Hieracidea orientalis (ScHrtEcEL) (Ieracidea berigora occidentalis et melvil- 
lensis MATH.). 
Math. handl. n:r 279. 
Variants. — I have been unable to get »paired adults and their young> 
(MATTHEW) of this form, or any other material from other parts of Australia, and so, 
although I have collected a series of 36 birds, I cannot do anything else but give 
here an easily comprehended grouping of the birds according to young and adult 
spec. and the occurrence of »light> and »dark» forms among them. (See Plate 3.) 
