Key to the Species and Subspecies. 
A. Uniform black. Males. 
a. Size large ; wing over 550 mm. ; no white flank 
patches . . . . , . . . . . . . F. m. listen, 
h. Size small ; wing over 535 mm. ; white flank patch 
on each side . . . . . . . . . . .. F. a. tunnyi. 
c. Size small ; wing under 535 mm. ; white flank patch 
on each side . . . . . . . . . . .. F. a. ariel. 
B. Breast white. Females. 
d. Size large ; wing over 590 mm. ; no light collar at 
back of neck . . . , . . . . . . F. m. listeri. 
e. Size small ; wing over 545 mm. ; rusty and white 
collar at back of neck . . . . . . .. F. a. tunnyi. 
f. Size small ; wing under 545 mm. ; rusty and white 
collar at back of neck . . . . . . .. F. a. ariel. 
Note. — I n the Australian forms the females are easily distinguished by 
means of the light collar on the hind neck as well as by size. In other races, 
as Rothschild and Hartert point out, the collar is observed in the female of 
the large form, but in those cases there is such a discrepancy in size that no 
confusion is possible. 
