Vallanadu is the one of the notable places where the Blackbust population exists. This sanctuary is located in an isolated hillock surrounded by scrub forest in Tuticorin district. Usually Blackbuck inhabits in the plain region but due to development of cities, agriculture and poaching, they have changed their residence to Vallanadu, Gunidy national park, Mudumalai sanctuary and Point Calimere sanctuary. This sanctuary is situated exactly at 16 kms distance from Tirunelveli.
The forest here is not so dense and lush, mostly they are covered with thorn scrubs. And so the species living here are mostly xerophytes and thorny hardwood. Few of the notable plants are Azadirachta indica, Dodonia viscosa, Carissa carandus, Pterolobium indicum and Euphorbia Acalypha fruticosa,
This sanctuary has got some common animals such as Black buck, Monkeys, Wild cat, Mongoose, Black naped Hare, Scaly Ant eater- Pangolin, Viper, and Rat snake. Compared to animals, birds are found in large numbers at this sanctuary, so far there are about 100 species of birds including Black winged kite, Curlew, Lapwing, Nightjar, Sparrows, Horned owl, Peacock, Heron, Stork, and Grey partridges. About 20-40 percent of the total population is occupied by Black Buck.
This sanctuary can be easily approached from Tirunelveli. The nearest airport is at Tirunelveli (16 km). There are buses from Tuticorin too, from Tuticorin this sanctuary is just 38 kms
Black buck can be found only during early morning and late in the evening. There are watch towers and shelter houses inside the sanctuary for the benefit of tourists. Climate is always sunny and rainfall is very rare in this region.