COPULATION-SOLICITATION DISPLAYS IN FEMALE CANARIES (SERINUS-CANARIA)- ARE ESTRADIOL IMPLANTS NECESSARY

The aim of this study was twofold: 1. To study the timing of copulatio n-solicitation displays (CSD) in female canaries during a natural bree ding cycle; 2. To address the question of the adequacy of invasive met hods such as oestradiol treatment. Towards these ends, we compared sev en oestradiol-implanted and eight control females. Moreover, temporal relationships between reproductive behaviour and plasma concentrations of luteinizing hormone and oestradiol were investigated. The results showed that: 1. CSD appeared about 3 d before egg laying, after the pe ak of nest building. The maximum number of CSD was observed at the beg inning of egg laying. CSD disappeared when the last egg was laid, at t he very beginning of incubation; 2. No significant difference was foun d between the two groups for any behavioural criterion, particularly C SD. No significant difference appeared between control and oestradiol- treated females for luteinizing hormone concentrations. In contrast, o estradiol-implanted females presented higher levels of oestradiol duri ng nest building and during egg laying, 9-13 d after implantation (med ian 2.53 and 1.47 ng/ml for implanted females vs 0.57 ng/ml and undete ctable levels for controls). Implantation had no effect on the progres s of nest building, CSD exhibition, egg laying and incubation. Our res ults suggest that implantation with oestradiol is not necessary in fem ale canary to obtain CSD since they breed readily in captivity and alr eady have enough oestradiol. The similar results in both groups lead o ne to question the necessity of oestradiol priming in some female choi ce experiments.