94 PYROMELANA FRANCISCANA 
dhurra. They have a pretty habit of rising and hovering 
with a jerky flight over the sea of glossy green dhurra 
blades, with their feathers puffed out until they look like 
balls of scarlet and black velvet; this action being accom- 
panied with a loud ‘purr-rr-purr-rr’ of the wings. They 
nearly always puff themselves out in this manner when 
approaching a female. I have seen beautiful head-dresses 
made out of their plumage by natives of the Upper White 
Nile, the black and scarlet feathers being set alternately in 
broad rings.” 
With regard to the moult in captivity, Dr. A. G. Butler 
purchased one autumn five males of P. franciscana and six of 
P. afra, and writes: ‘All these birds continued to develop 
their nuptial plumage up to the first frosts, when the change 
was arrested and the bright colouring gradually receded from 
the feathers, so that in about six weeks the birds had all 
resumed their winter plumage. 
«Several views have been put forward to account for the 
change of plumage in birds, but when the colouring gradually 
comes and again recedes from the same feathers, the casting 
of a disguising film will not account for the second operation. 
“In Pyromelana the change of plumage is very slow; the 
feathers daily gain in intensity, the pale buff of the under 
parts getting scarcely perceptibly deeper, until at length the 
velvet black and the fiery orange in P. franciscana appear as 
mere spots or shaft-streaks, which gradually expand fan-wise 
towards the outer fringes of the feathers. This spotting, 
however, is very uneven, some feathers being developed in 
advance of others, so as to give the bird a very patchy 
appearance. In the bright yellow and black plumage of 
P. afra this is even more noticeable. 
“ At the change of plumage the flank-feathers and upper 
tail-coverts are moulted out, being replaced by long soft 
