Vieillot, Nouv. Dict, d'Hist. Nat, nouv. ed., ix, p. 587(1817), ex Levaillant, Le Dongri, Ois. d'A frique, pi. 170, Java; Stuart Baker, Novitates Zool., xxv, p. 291 (1918).
I have dealt with this species in great detail in lor. cit. and space is not available here to repeat my remarks The great difficulty in determining the races is due not only to the extreme individual variation but, also, to the fact that the species is a confirmed wanderer in the non-breeding season and we therefore cannot with certainty say what Museum specimens are breeding-birds and what local visitors only. If we could eliminate all but breeding-birds, we should almost certainly find the differences greatly accentuated. If the contrary was found to be the case, some of the forms now accepted would have to be suppressed. Of the races I accepted in 1918 as fairly well recognisable, the following are found within the limits of this work:—
Key to Subspecies.
A. Wing average 127 mm.; tail 131 mm.
General colour a bluish grey, not very
dark D. l. disturbans, p. SCO.
B. Wing average 132 mm.; tail 138 mm.
General colour much darker; more
indigo-grey D. l. nigrescens, p. -361.
C. Wing average 146 mm.; tail 150 mm.
General colour much the same as in B. D. l. hopwoodi, p. 801.
D. Wing average 141 mm.; tail 152 mm.
General colour decidedly paler, more
grey, less indigo D. l. stevensi, p. 30:2.
E. Wing average 134 mm.; tail 148 mm.
General colour as in D D. l longicaudatus, p, 362.
F. Wing average 131 mm.; tail 139 mm.
General colour rather darker than in
D and E D.l. minimus, p. 364.