Biannual breeding and moult-breeding overlap of the Chestnut-bellied Starling Spreo pulcher

At Kano, Nigeria, the Chestnut-bellied Starling Spreo pulcher has two distinct breeding seasons, a long one from the late dry season to the early rains (February to June) and a short one in September, October and rarely November following the rains. Males have enlarged testes from February to October, so the breeding periods are probably determined by the reproductive condition of the females. Most individuals breed in both periods but some breed only in the pre-rains period. Adult wing-moult begins in March and April, overlapping with any breeding attempts in the latter half of the pre-rains session; some birds continue to moult into the post-rains session. Post-juvenal wing-moult is from August to January for birds reared in the previous pre-rains period and is simultaneous with adult moult for birds reared in the post-rains period. An increase in ambient temperature may be the most important proximate cue determining the pre-rains and also the post-rains breeding periods. A correlation between moult-breeding overlap and co-operative breeding for some tropical birds is suggested and discussed briefly.