An Evaluation of the Suitability of Contraceptive Methods in Golden-headed Lion Tamarins (leontopithecus Chrysomelas), with Emphasis on Melengestrol Acetate (MGA) Implants: (ii) Endocrinological and Behavioural Effects
In order to be suitable, a contraceptive method should have little or no effects on social organization or behaviour. In callitrichids, changes in socio-sexual interactions between group members, due to hormonal changes induced by contraception, may have consequences for the reproductive
inhibition of offspring in their natal group. This may lead to an increased rate of inbreeding. In this paper we report on the endocrinological and behavioural effects of contraception in golden-headed lion tamarins, using data obtained through a world survey and an observational study. Hormonal
analysis of urinary oestrone conjugate levels in melengestrol acetate (MGA)-implanted females confirmed earlier preliminary findings (Van Elsacker et al 1994): MGA implants inhibited reproduction through the suppression of ovulation and regular ovarian cycles in the implanted female,
while the occurrence of ovarian cycles in the oldest female offspring of each group was not affected. Sexual interactions between the dominant adults still occurred but underwent temporal changes. Reproductive inhibition in female offspring was maintained. Social interactions between group
members altered in a non-consistent way but did not have an impact on the stability of the study groups during the study. In principle, MGA implants do not have a detrimental impact on the behaviour of group members. The suitability of MGA implants from a behavioural point of view depends
on the extent to which those involved wish to preserve the entire range of natural behaviours for this species. The behavioural effects of other contraceptive methods are still largely unknown.