For decades, winter at Jahangirnagar University (JU) was heralded not by a change in temperature, but by sound.
At dawn, thousands of migratory ducks would rise from the campus lakes in sweeping formations, their calls echoing over mist-covered water before settling again.
The spectacle drew students, birdwatchers and photographers alike. This winter, that familiar sound never arrived.
By late December — traditionally peak season for migratory birds — most campus waterbodies remained unnervingly quiet. Where 6,000 to 7,000 birds once gathered each winter, researchers recorded only about 1,500 this season, concentrated largely in one or two restricted areas. The sudden silence has raised growing concern: why are the birds no longer coming?
Located on the outskirts of Dhaka, Jahangirnagar University has long been regarded as one of Bangladesh’s most important winter refuges for migratory birds. Since the first recorded sightings in 1985, researchers from the Department of Zoology have documented around 210 bird species on campus, including 126 resident species. During winter, 20 to 25 migratory species—mostly ducks and other waterfowl—used the lakes as daytime resting grounds.
That reputation is now under threat.
Data collected by university researchers show a sharp decline over the past three years. During the quieter Covid-19 period of 2019–20, winter counts stood at around 6,000 birds. Numbers dropped to between 2,500 and 3,000 in subsequent seasons, before falling further to roughly 1,500 this winter. Several lakes that once hosted large flocks are now almost empty.
“This is not a normal fluctuation,” said Professor Md Kamrul Hasan of the Department of Zoology. “It reflects a broader ecological decline. The disappearance of migratory birds is a visible symptom of ecosystem collapse.”
The loss is not only numerical. Several species that were once regular visitors have stopped arriving altogether.
Wildlife photographer and researcher Auritro Sattar noted the absence of species such as the African knob-billed duck, cotton pygmy goose, common teal and yellow-wattled lapwing. Bush birds including the Siberian rubythroat and Eurasian wryneck, along with raptors such as the long-legged buzzard and crested serpent eagle, have also declined sharply.
“What we are seeing now are only the weaker waves of migration,” Auritro said. “The birds are concentrating in the few places where disturbance is minimal. Most of their former habitats have become unsuitable.”
At Jahangirnagar University (JU), delayed habitat management has further undermined prospects for migratory birds this winter, the researcher said. “As temperatures dropped below 20°C, aquatic vegetation declined and food diversity shrank. With insufficient feeding resources, migratory birds failed to settle in the campus wetlands and eventually moved on,” Auritro added, underscoring how mistimed ecological management can negate earlier conservation gains.
According to field observations, migratory ducks — highly dependent on aquatic vegetation —are now largely confined to the Wildlife Rescue Centre (WRC) Lake, where public access is limited. Fish-eating birds, however, remain scattered across several lakes, pointing to a severe decline in the aquatic plants essential for duck species.
Experts attribute the downturn to mounting human pressure. Unplanned construction has reduced green cover and disrupted flight paths, while several lakes have been leased for aquaculture, altering natural ecosystems. Noise and light pollution, littering and unrestricted access to lake shores have further degraded habitats.
Delayed habitat management has compounded the problem. Excess water hyacinth was removed in December—just before winter—eliminating key food sources at a critical time. Beyond the campus, the situation is even bleaker. Wetlands across Savar, Ashulia and Dhamrai have been rapidly replaced by housing and industrial developments, depriving birds of feeding grounds.
“The birds rest on campus but feed elsewhere,” Professor Hasan said. “Without surrounding wetlands, no amount of conservation within the university will bring them back.”
The fading winter chorus at Jahangirnagar University is more than a loss of beauty. It is a warning that without stronger protection, regional wetland conservation and public awareness, the silence may soon become permanent.