Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) head portrait, Koram island, Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) grooming, Koram island Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long-tailed macaques (Macaca fascicularis) two juveniles sitting close together. Koram island, Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) approaching camera, Koram island, Khao Sam Roi Yot National Park, Thailand.

Anup Shah / Long-tailed macaque (Macaca fascicularis) juvenile sticking tongue out. Khao Sam Roi Yot National Park, Thailand.

Christophe Courteau / Long-tailed macaques (Macaca fascicularis) grooming, with baby playing nearby, Bako NP, Sarawak, Borneo, Malaysia.

Anup Shah / Long-tailed macaque (Macaca fascicularis) baby aged 2-4 weeks clinging to its mothers back. Bako National Park, Sarawak, Borneo, Malaysia.

Edwin Giesbers / Long-tailed / Crab-eating macaque (Macaca fascicularis) head portrait of baby, Bako National Park, Sarawak, Borneo, Malaysia

Edwin Giesbers / Two Long-tailed / Crab-eating macaques (Macaca fascicularis) foraging on coastline at low tide, Bako National Park, Sarawak, Borneo, Malaysia

Edwin Giesbers / Four Long-tailed / Crab-eating macaques (Macaca fascicularis) foraging on coastline in shallow water with waves, Bako National Park, Sarawak, Borneo, Malaysia

Edwin Giesbers / Two Long-tailed / Crab-eating macaques (Macaca fascicularis) foraging along coastline in shallow water, Bako National Park, Sarawak, Borneo, Malaysia

Edwin Giesbers / Long-tailed / Crab-eating macaque (Macaca fascicularis) feeding in darkness before dawn, Bako National Park, Sarawak, Borneo, Malaysia

Edwin Giesbers / Long-tailed / Crab-eating macaque (Macaca fascicularis) foraging on coastline, Bako National Park, Sarawak, Borneo, Malaysia

Suzi Eszterhas / Long tailed macaque (Macaca fascicularis) trying to take banana from Sumatran Orangutan (Pongo abelii and young baby, North Sumatra, Indonesia. Critically Endangered

Anup Shah / Crab eating / Long tailed macaque (Macaca fascicularis) feeding on Horseshoe crab, Sumatran Coast Indonesia

Anup Shah / Crab eating / Long tailed macaque (Macaca fascicularis) swimming, Sumatran Coast, Indonesia

Anup Shah / Crab eating / Long tailed macaque (Macaca fascicularis) swimming, Sumatran Coast, Indonesia

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) looking underwater for food thrown by people, Thailand

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) pair looking underwater for food thrown by people, Thailand

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) pair grooming, Khao Sam Roi Yot National Park, Thailand

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) using stone tool to break shell, Khao Sam Roi Yot National Park, Thailand

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) group, Khao Sam Roi Yot National Park, Thailand

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) troop, Khao Sam Roi Yot National Park, Thailand

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) using stone tool to break shell, Khao Sam Roi Yot National Park, Thailand

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) feeding on crab, Khao Sam Roi Yot National Park, Thailand

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) on ball on beach, Thailand

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) female with baby, using stone to crack open shell in intertidal zone, Koram island, Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) baby suckling, Koram island, Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) with baby, using stone to break open shell Koram island, Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) female with baby, using stone tool to smash shell. Koram island, Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) using stone to break open oysters. Koram island, Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) juvenile and adult playing in water, Koram island, Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Slingshots used by monks to prevent Long-tailed macaque (Macaca fascicularis) from entering certain areas of temple, Koram island, Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long tailed macaque (Macaca fascicularis) with an ice cream which it was given at a temple. Thailand

Cyril Ruoso / Long tailed macaques (Macaca fascicularis) playing on cliffs, jumping into the sea near city, Thailand

Cyril Ruoso / Long tailed macaques (Macaca fascicularis) playing on cliffs above the sea wtih town buidings in background, Thailand

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) living in disused building, Thailand.

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) living in disused building, Thailand.

Cyril Ruoso / Long tailed macaques (Macaca fascicularis) playing in the sea, Thailand.

Cyril Ruoso / Long tailed macaque (Macaca fascicularis) sititng on beach near city,Thailand.

Cyril Ruoso / Long tailed macaque (Macaca fascicularis) troupe playing and jumping in the sea, Thailand.

Cyril Ruoso / Long tailed macaque (Macaca fascicularis) troupe playing in the sea, Thailand.

Cyril Ruoso / Long tailed macaque (Macaca fascicularis) troupe playing in the sea, Thailand.

Cyril Ruoso / Long tailed macaque (Macaca fascicularis) troupe playing and jumping into the sea, Thailand.

Cyril Ruoso / Long tailed macaque (Macaca fascicularis) juvenile playing with mirror, Gulf of Thailand, Thailand.

Cyril Ruoso / Long tailed macaque (Macaca fascicularis) juvenile playing with mirror, Gulf of Thailand, Thailand.

Cyril Ruoso / Long tailed macaque (Macaca fascicularis) sitting on football on beach, Gulf of Thailand, Thailand.

Cyril Ruoso / Long tailed macaque (Macaca fascicularis) troop playing in the sea, Thailand.