THE CHANaEABLE HAWK-EAGLE 
Spi^^ius cirrhatus HmtttBtus (Horsf.) 
Description: — This hawk-eagle is interesting in that it 
furnishes us with an excellent example of dimorphism — ^tlie 
condition existing when one species occurs in two distinct 
forms. Considering their plumage alone many birds are of 
course sexually dimorphic. The reader will at once call to 
mind a number of instances : most species of wild ducks have 
quite distinct phimages for the male and female. Occasionally 
dimorphic forms of a species occur quite independently of 
sex. The Spist^Uts under discussion is a striking example of 
this for it is found in two such distinct piumages that it is not 
surprising the old naturalists regarded these phases as distinct 
species and gave them natnes accordingly. In this species 
the male is smaller than the female : a sexual difference in size 
is very common in the birds of prey. 
The dark phase is almost entirely deep blackish-brown 
above and below unrelieved by any distinct markings. Among 
local birds it is unmistakable— a nearly uniform black eagle- 
like bird only slightly smaller than the sea-eagle although 
considerably larger than the brahminy kite. 
In the light phase the underparts are whitish, more often 
than not spotted or splashed with dark brown. The head may 
be light like the underparts or on the other hand may resemble 
the upper parts which are brown; the tail has dark bands. 
The wing is approximately from 15 to 17 inches. 
The iris is bright yellow, the bill black and the feet yellow. 
Distribution: — This bird is found in India, Burma, the 
Malay Peninsula and thence through the islands to the Philip- 
pines, Closely allied races occupy the Lesser Sunda Islands 
and Celebes. 
Status in Singapore:— Th\s fine bird can often be seen in 
Singapore: in fact we suspect that the majority of the large 
raptores that are seen here, excluding the very large sea-eagle, 
belong to this species. A pair may often be seen in the jungle 
at the Botanic Gardens. In 1S98 Ridley recorded tliat it 
[loi] 
