 The zoo is also home for wintering migratory birds such as ducks, and sports a sizable wetland inside the zoo grounds.Since the zoo is enveloped by urban settlements for miles, the zoo wetlands are the only resting spot for some of the birds and are a focus of conservationists in Kolkata.However, the number of migratory bird visiting the zoo dropped from documented highs by over 40% in the winter of 2004–2005.