When a British birdwatcher documented a small bird nesting in the wetlands of what is now called Salt Lake in 1875, Bengal’s riverbanks used to throb with wilderness.
Almost 150 years later, researchers from the Zoological Survey of India (ZSI) again spotted the chestnut-capped babbler (Timalia pileata) in the riverine grasslands of Howrah, marking the first documented breeding population of this elusive bird in south Bengal in independent India.
“This is the first confirmed sighting of the species in this region in recent times, especially with evidence of nesting and breeding. It’s a significant record for south Bengal,” said Kaushik Deuti, co-author of the study, published in the latest edition of Indian Birds on Tuesday.
Allan Octavian Hume, one of the founders of the Indian National Congress, is also the author of The Nests and Eggs of Indian Birds, published in 1889. In the book, he quoted J.C. Parker — a contributor to Hume's ornithological records — of having spotted a nest of chestnut-capped babbler at Salt Lake on August 14, 1875.
The chestnut-capped babbler is a timid and insectivorous bird. It typically remains hidden in reed beds and dense grasslands, making sightings difficult.
Between December 2022 and March 2025, the ZSI team conducted 102 field visits across the grasslands along the Rupnarayan and Damodar rivers. The bird was found in 23 sites — most notably at Orphuli, Kamardaha, Amdanga, Char Kantapukur and Kalbansh — of which 18 were near the Rupnarayan and five near the Damodar.
The grassland patches, consisting mainly of tall wild grasses such as kash and khori, are unprotected areas and currently under threat from expanding floriculture, especially for marigold and hibiscus. Researchers said the grasses, which form thick and fluffy patches, create the perfect cover for shy birds such as the chestnut-capped babbler to live and breed.
“These grasslands are being rapidly cleared using machines to make way for commercial flower cultivation,” said Deuti. “The chestnut-capped babbler is a grassland-dependent species. If the habitat vanishes, so will the bird.”
The study also shows evidence of previously unrecorded sexual dimorphism, challenging the existing ornithological literature. Sexual dimorphism stands for visible differences between males and females of the same species. “We observed a consistent difference in iris colour — males had a red iris and females a black one,” said Sekhar Pramanik, co-author and field researcher.
“Only the red-eyed individuals were seen singing and displaying during the breeding season. And this is a significant behavioural marker.”
The researchers also recorded three distinct vocalisations — alarm, territorial and breeding calls. This finding has added valuable data to the scant sound archives available from Bengal. “It’s clear the vocal repertoire of this species is more complex than previously believed,” Pramanik said.
The researchers also noted breeding activity at four of the 23 sites, with nests found between February and April. However, the nests were later destroyed when grasslands were burnt for floriculture, highlighting the fragile coexistence between wildlife and human activity. “Sadly, even during the short breeding window, grasslands are being set ablaze for new crops,” said Deuti.
Experts say the species’ survival in the region depends heavily on urgent habitat conservation. “Without any formal protection, the grasslands might be lost forever,” said Deuti. “We may be seeing the last stronghold of this species in south Bengal.”
“Wetlands and grasslands are rapidly disappearing because of unsustainable human activities,” said ZSI director Dhriti Banerjee. “I am proud of our researchers who documented the presence of such a rare and elusive species. But this discovery is also a reminder — if we want birds like the chestnut-capped babbler to survive, we must urgently protect their habitats. Conserving wetlands and grasslands is essential not just for Bengal, but for maintaining ecological balance across the country.”
The researchers hope their findings will lead to conservation interventions and public awareness.
Deuti said: “This bird has quietly held on in the margins. Whether it survives now depends on how much value we assign to the margins.”