The cotton-top tamarin is a small tree-dwelling monkey that is only found in the dry forests of north-western Colombia. The species is listed by IUCN as critically endangered, which means it is threatened with extinction in the wild. The species used to be abundant in its native habitat, but tends of thousands were captured in the late 1960s for biomedical research, and current threats are habitat destruction and capture for the pet trade.
Special survey methods required!
Cotton-top tamarins are very hard to survey - they live in small family groups high up in the forest canopy and flee at the first sign of approaching humans. Hence standard, visual counting methods do not work. In collaboration with the Colombian conservation charity, Proyecto Titi, we developed a method that works. It relies on the fact that cotton-tops are territorial, and will approach if they hear a 'lost monkey' call to find out who it is. We therefore designed a survey method where two teams of surveyors walk in parallel, 200m apart, each playing recordings of cottontop tamarin long calls from a high-quality playback device. All groups within the space between the teams are assumed to respond (we tested this), and we count only groups that approach the teams from within the strip.
Watch a video about this study
For more details, there's a short video describing the development of the methods, and our first successful study, on YouTube here
This was the first ever population survey of the species, and we estimated there were approximately 7,400 animals left in the wild in 2005. Proyecto Titi undertook a follow-up survey in 2012 and we estimated there were 6,900 individuals remaining.