The ways in which Lion-tailed macaques can be protected are – 

1. By stopping encroachment into lion-tailed macaque habitats, 
2. Controlling hunting, road-kills and electrocution. 
3. Management of forest fragmentations,
4. Restoration of degraded habitats and conservation breeding.
5. Building bridges out of wooden ladders to link the canopies across a road easy passage through the forest.

Read more on the characteristics and habitat of Lion-tailed Macaque on the given link.

Further readings-

1. The Wildlife Protection Act
2. CITES – Convention on International Trade in Endangered Species