A constant 15-hr daily photoperiod led to a prolonged reproductive phase in the female tropical weaver finch Ploceus philippinus. Thyroxine treatment (1.4 and 2.8 μg on alternative days for 5 mo) completely suppressed follicular development, and ovarian and oviducal weight, but had no effect on the liver and body weight in birds maintained on 15-hr daily photoperiods. A "thyroid-sensitive" hypothalamo/hypophyseal/gonadal axis, as exhibited by this bird and many other birds of mid and low latitudes where the degree of insolation is large, may serve as a safety mechanism against unseasonal gonadal growth and hence might be of adaptive significance in tropical photoperiodic finches. © 1974.
Chandola, A., Thapliyal, J. P., & Pavnaskar, J. (1974). The effects of thyroidal hormones on the ovarian response to photoperiod in a tropical finch (Ploceus philippinus). General and Comparative Endocrinology, 24(4), 437–441. https://doi.org/10.1016/0016-6480(74)90157-9