Monkeys while hiking up to 47 rest area from Penang Botanical Gardens

Usually the monkeys at the Penang Botanical Gardens are the brown haired type (I don't know what species name they are) but last few years there are these black haired monkeys start to appear. They seems harmless and they don't attack humans or eat trash from trash cans. They actually eat leaves and like to be on the trees. Compare to the predominately brown haired type, they are vicious especially when you have food in your hands and they would snatch it at every opportunity they would have. 

Usually you can spot them while hiking from a little jungle (steps) trek from inside the Botanical Gardens to "47" (thats what the local calls it) rest area.