10/03/14 Tangkoko forest, North Sulawesi, Indonesia

Tangkoko is one of the last remaining strongholds of the Critically Endangered Sulawesi crested black macaques (Macaca nigra). Wildlife photographer Andrew Walmsley is in the field documenting the work of Selamatkan Yaki, a non-governmental organisation (NGO) working to protect the monkeys which are threatened by habitat loss and the illegal bushmeat trade.

Two macaques play fighting. Scuffles like this are important in social bonding and practicing for more serious fights later on in life.