Fig. 1. Variation in dry oviduct mass (mg) during the laying cycle in female zebra finches in relation to stage of ovarian development. 1st egg, day first egg was laid; F1 foll, one or more yolky follicles present; 0 foll, no remaining yolky follicles; ovid egg, oviductal egg present. Columns sharing the same letter are not significantly different (P>0.05).