Individual study: Impact of a trade moratorium on populations of yellow-crested cockatoos Cacatua sulphurea at four forest sites on Sumba, Nusa Tenggara, Indonesia
Cahill A.J., Walker J.S. & Marsden S.J. (2006) Recovery within a population of the Critically Endangered citron-crested cockatoo Cacatua sulphurea citrinocristata in Indonesia after 10 years of international trade control. Oryx, 40, 161-167
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Use legislative regulation to protect wild populations
A before-and-after study on Sumba, Indonesia (Cahill et al. 2006), found that estimated population densities of citron-crested cockatoos Cacatua sulphurea citrinocristata increased between 1992 and 2002, following the imposition of a ban on trade in wild-caught birds in 1993. Increases were seen over the entire study and at two out of four forest sites (by 130-700%). One further site showed no change in density and the final site a possible decrease. No evidence was found for forest contraction (i.e. increased densities are thought to reflect an increase in total population sizes), total recorded birds increased by 56% from 1992-2002; significantly more birds were in groups of two or more and the estimated population size was 90% larger in 2002. The authors note that the trade ban has not been enforced perfectly, but that it has significantly reduced the number of wild-caught birds being traded.