Asking for mating with females, males from different neighboring communities use different gestures to communicate their wish. While males from the North-East group use knuckle-knock signals, males from the three other communities in Tai use heel-kicks instead. We provide three lines of evidence that these gestures are based on signal traditions: by finding variation across populations, across neighboring communities and across time in the same community. For the last line of evidence, long-term data collection over the last 30 years helped to show, that the knuckle-knock was once the gesture of choice by the North group males. This ended due to the demographic decline of the group and the last two adult males being shot by poachers. Without a male role model the copulation solicitation signal of knuckle-knock disappeared and did not reappear again, despite of several adult males competing over the attention of females again in North group. Such loss of culture provides an argument for why cultural variation should be taken into account by conservation initiatives of endangered animals.
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