Testis Growth and Regression in Harmful Birds in the Punjab in Relation to Some Environmental Factors.

Abstract

Testis growth and regression were studied, in relation to environmental temperature, sunshine, relative humidity and rainfall, in the house crow Corvus splendens, the common myna Acridotheres tristis and the house sparrow Passer domesticus, all of which are harmful species in the Punjab. Testis weight varied greatly during the year, but the species differed in their response to environmental conditions. The crow and the myna have active testes during May-July and April-July respectively; in the sparrow the testes are active twice in the year, February-June and September-October. The environmental factors are not sufficient to regulate the reproductive behaviour of these birds in the Punjab, and it is suggested that the reproductive state of birds is determined by a combination of exteroceptive and enteroceptive factors which varies considerably among species.