New research has revealed why members of a species of monkey in Uganda join in with a dawn chorus each morning.
Scientists from the University of St Andrews in Scotland state the activity appears to be intended to show off a primate's size and status among the group, the BBC reports.
Dr Anne Marijke Schel found that, by playing a recording of the call of a diminutive male guereza colobus monkey, it would always receive a response.
"We think it's the case that if someone very small calls, you counter-call to show off that you're bigger and more dominant," she said.
Evolutionary biologist Dr Reinmar Hager of the University of Manchester explained dawn chorusing, although usually associated with songbirds, plays an important part in the structure of primate society – especially among competing males.
A greater knowledge of their social systems can help in conservation efforts, he continued, as well as helping understand how more complex human interactions may have evolved.