It is the largest bird sanctuary of India covering 120sq km situated in Ahmedabad, Gujarat. It became a bird sanctuary in 1969 and the Ramsar Convention Site in 2012. There are 225 species of birds with 140 being water birds. And around 210 species of birds arrive here every winter from the north including Pelicans and Storks.

The question pertains to the largest bird sanctuary in India, which is Nal Sarovar Bird Sanctuary. This sanctuary is located in Ahmedabad, Gujarat, and covers an area of 120 square kilometers. It was established as a bird sanctuary in 1969 and became a Ramsar site in 2012, which is an international treaty for the conservation and sustainable use of wetlands. The Ramsar Convention Site designation highlights the importance of the sanctuary for wetland conservation and biodiversity.

Nal Sarovar Bird Sanctuary is a significant habitat for a wide variety of bird species. It supports over 225 species of birds, with 140 of these being water birds. The sanctuary is particularly notable for the large number of migratory birds that visit it every winter. Around 210 species of migratory birds, including Pelicans and Storks, arrive from the north to spend the winter in the sanctuary. This makes Nal Sarovar a crucial stopover and wintering ground for these birds.

It is important to distinguish Nal Sarovar Bird Sanctuary from other bird sanctuaries in India. For example, Thattekad Bird Sanctuary is located in Kerala and is not the largest bird sanctuary in the country. Similarly, Keoladeo National Park, also known as Bharatpur Bird Sanctuary, is located in Rajasthan and does not match the description provided in the question. Nal Sarovar Bird Sanctuary stands out due to its size, location, and the number of bird species it supports, making it the correct answer to the question.