ROMILA SAHA Birds at the Santragachhi jheel. (Sanat Kumar Sinha) Fewer birds have made the Santragachhi jheel their home this winter. Overgrowth of water hyacinth in the 13,75,000sq ft lake, the largest hub of waterfowl around the city, could be one of the reasons, according to experts. Last year, 5,152 migratory and local birds were counted at the jheel, said Kushal Mookherjee of NGO Prakriti Samsad, which conducts the annual Asian Waterfowl Census.