Since 2005, Borneo Nature Foundation has produced 50 peer-reviewed papers/book chapters on gibbons plus several reports, standard operating procedures, training materials and DVDs. Here we present 15 years of long-term wild gibbon behavioural data that represents one of the longest continuous datasets on any gibbon species. Not only has our knowledge of gibbons increased, but the profile of the small apes has also increased since 2005. This review presents data gathered by the Borneo Nature Foundation, highlighting new insights into gibbon behavioural ecology and conservation lessons learnt. Gibbons are proving to be relatively consistent in their behaviour, irrespective of changes in group demography. Although threats to gibbons across their range remain high, they demonstrate their ability to adapt their behaviour to anthropogenic disturbance. While flexible in behaviour (e.g. adapting travel routes in disturbed habitat), there is a threshold at which a forest becomes unsuitable for sustaining viable gibbon populations. We must understand more about their behavioural ecology in order to determine this threshold to help protect gibbons.