The number of migratory birds in Rajshahi has fallen markedly this winter. Experts and observers say the main causes are destruction of habitat on the chars of the Padma, growing human disturbance and excessive light pollution in the city.

Local birdwatchers and researchers at Rajshahi University say bird numbers on the Padma banks in early December have fallen markedly compared with a decade ago. The riverbanks once hosted thousands of migratory ducks, plovers and waterbirds; now only scattered flocks remain.

Hasnat Roni, a Rajshahi birdwatcher who has observed the river for 14 years, says bird numbers on the Padma chars have fallen to less than a tenth of their former level since 2010. Along stretches of the Padma where migratory birds were once widely seen from November to March, sightings are now rare even in December and January, he said.

A research paper on population estimates, species composition, colony characteristics and the spatial description of colonial waterbirds in north and north-east Bangladesh found that, in scientific surveys carried out in four divisions between 2021 and 2023, 40 per cent of the country's waterbird colonies were in Rajshahi. Of 367 colonies identified nationwide, 157 were found in Rajshahi, the highest in the country. But these species are now at risk as riverine mudflats, wetlands and trees suitable for nesting disappear.

The research says 66 per cent of abandoned breeding sites in the country were lost to human disturbance and habitat loss, which is clearly visible on the Rajshahi chars. Researchers say the steady degradation of the Padma's wetland habitats, particularly the destruction of wetlands, mudflats and nesting trees, now threatens these species.

Hasnat Roni said the intense night-time lighting of Rajshahi city is disrupting the traditional flight paths of migratory birds.

According to the Rajshahi City Corporation's engineering department, decorative street lights were installed on almost every road in the city between 2020 and 2024. On the 3.1km road from the Kalpana Cinema Hall intersection to Talaimari alone, 130 decorative poles have been installed, each with 13 modern LED bulbs.

In addition, 180 modern decorative garden light poles have been installed along the embankment beside the road, each fitted with five modern LED bulbs.

These upward-facing, chandelier-like lights, known as Rajmukut (crown), have completely altered the migration route, Roni said. Migratory birds usually travel at night following natural cues, but when the whole riverbank is flooded with artificial light they become disoriented and avoid Rajshahi.

He added that many species that once came close to the city now move elsewhere before dawn. "They come near Rajshahi, but the sky is too bright. Their timing is disrupted and they move away."

Professor Aminuzzaman Md Saleh Reza of the zoology department at Rajshahi University said light pollution is interfering with nocturnal animals, leading migratory birds astray and changing the ecosystem of the Padma banks and nearby chars.

He added that migratory birds are also flying to other parts of the country because unprecedented rain in early November delayed the emergence of char land in the Padma. The district once had thousands of open water bodies, including canals and beels; almost all have now been turned into commercial fish farms, and migratory birds do not take shelter in these ponds.

Professor Saleh Reza said the destruction of mudflats and the loss of undisturbed chars are also to blame. Sand extraction, motorbikes on the chars, crowds of tourists, constant boat traffic and illegal hunting are shrinking safe feeding grounds.

Hasnat Roni said migratory birds increasingly prefer places with minimal human interference, even if that means moving across the border. Where the Padma branches into Indian territory, he said, birds settle comfortably on the Indian side but avoid the Bangladeshi side across the river, which shows how intolerant of disturbance the birds have become.

Although large-scale poaching has fallen compared with the past, illegal hunting still goes on at night in remote char areas, Roni said, and even limited hunting pressure affects populations that are already shrinking.

Researchers also noted that Bangladesh has no co-ordinated population count of winter migrants, which leaves conservation efforts scattered and reactive. There is no national monitoring system, yet the decline is clearly visible on the ground.

Professor Saleh Reza said a decline in key migratory birds could have cascading effects on biodiversity and ecological balance, meaning less control of fish and insects, less pollination or seed dispersal, and in turn lower productivity for rice farmers.

With peak migration expected from mid-December into January, observers feared that the continued decline could lead many species to avoid the region altogether. "If disturbance continues at this level, Rajshahi will soon drop off the migratory map," Roni warned.

Jahangir Kabir, wildlife inspector at the Rajshahi divisional Wildlife Management and Nature Conservation Circle, said it is true that human disturbance and shrinking habitat are affecting migratory bird numbers, but no conclusion about the scale of the decline can be reached without proper scientific research.

He said they are meeting farmers and residents on the chars, distributing leaflets and raising awareness about protecting migratory birds. "We will stay active throughout the winter and run regular patrols to prevent illegal hunting. Anyone involved will be brought to justice."

Source: Jagonews24. First published in Bengali on The Agro News.