Do not be surprised to spot migratory birds in summer
Over-summering, where migratory birds choose to extend their stay beyond winter, is a common phenomenon. Conservation efforts too, therefore, have to be extended throughout the year
One early morning in the first week of May, our photographer Mohammad Minhaj Uddin went to Lal Char in Noakhali's Hatiya upazila. Being a local of this region, he was completely taken aback to see flocks of Kentish Ziria, or the Kentish Plover, there.
As the gentle waves of the Bay of Bengal lapped against the sandy shore, hundreds of birds scattered along the coastline. With nimble steps, they darted back and forth, probing the wet sand for tiny crustaceans and insects hidden beneath the surface.
Minhaj had his reasons to be surprised.
It is common knowledge that these ground-nesting migratory birds usually arrive in the coastal areas of Bangladesh from North and Central Asia and North Africa before the onset of winter.
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Some juvenile birds who are not yet sexually mature stay back in non-breeding sites, like Bangladesh, throughout the summer. "So, it is flawed to associate migratory birds with only the winter season
In the past, Minhaj had only seen these birds during the winter months, with his first encounter with them dating back to 2015. A local guide named Mahbub, who had tagged along with him, also confirmed that the presence of Kentish Plovers during this time of the year was "rather unusual."
Therefore, seeing them in summer, especially in the very first month of the Bangla calendar, seemed strange to Minhaj. The first thought that struck his mind was, "Now that these migratory birds are coming to Bangladesh in summer, surely this is the result of nature becoming aggressive in the face of climate change."
Upon learning his experience, I too wondered what the possible reason behind this might be and decided to dig deeper into the matter.
But what I discovered after consulting with experts was rather astonishing. While climate change is indeed a significant threat to nature, it turned out that the phenomenon of migratory birds being spotted in Bangladesh in May was nothing new.
Experts termed it "quite natural" and debunked the common misconception that migratory birds can only be seen in Bangladesh during winter. This also underscores the importance of conservation efforts being maintained consistently.
Sayam U Chowdhury, a conservation biologist with interests in the ecology and conservation of threatened species in Asia, said that many shorebirds, particularly the young ones, do not travel north during summer.
This phenomenon of migratory birds choosing to extend their stay beyond the typical winter months and remaining in the coastal and wetland areas of the country during the summer season is known as "over-summering".
So, it is very likely that the Kentish Plovers Minhaj and Mahbub spotted in Lal Char did not arrive in Bangladesh in May. Instead, they probably decided to extend their stay beyond the winter season, having arrived in the country much earlier.
To understand the over-summering behaviour of shorebirds in Bangladesh, Sayam and his team conducted a five-year study (2011–2015) on the shorebirds of Sonadia Island, Cox's Bazar. They observed the birds during both the winter (January–March) and summer (May–August) seasons.
During this period, 23 shorebird species were recorded over-summering on Sonadia Island from May to August. All 23 were observed during both the summer and winter periods, with the most abundant over-summering species being the Lesser Sand Plover, Greater Sand Plover, and Eurasian Curlew.
According to Sayam, "no significant differences were found between mean summer and mean winter counts in case of large to medium size shorebirds. A high proportion of those larger species visiting Sonadia Island were first-year birds."
Since a substantial number of globally threatened shorebirds were recorded over-summering on Sonadia Island, Sayam recommended that conservation efforts should be undertaken throughout the year.
Meanwhile, Delip Kumar Das, assistant professor of Zoology at Jagannath University, who is now pursuing his PhD at the University of Groningen, informed that he visited Lal Char several times from October to March for surveying shorebirds and noted that "Kentish Plover is indeed a common species there."
According to him, migratory birds in Bangladesh are seen in the highest numbers from autumn to spring, and species like the Black-tailed Godwit and Eurasian Curlew stay for as long as nine months in Bangladesh each year.
Most migratory birds begin arriving in Bangladesh as early as August, with their numbers peaking around mid-November. The period from April to July is considered the breeding season for migratory birds such as the Kentish Plover.
During this time, they migrate back to the north to engage in courtship rituals, nest building, egg laying, and rearing of their chicks.
Then again, some juvenile birds who are not yet sexually mature stay back in non-breeding sites, like Bangladesh, throughout the summer. "So, it is flawed to associate migratory birds with only the winter season," Das said.
In that case, why are migratory birds mostly seen during the winter season? As per Das's argument, during the dry season, water is scarce, causing migratory birds to congregate in a few select sites where water is available.
However, during the monsoon season, they disperse across coastal areas, including remote locations where photographers or cameramen rarely venture to document their presence.
Das further added that migratory birds are attracted to Bangladesh, particularly its coastal areas, mainly due to the abundance of food and the opportunity to rest and relax.
Coastal areas experience regular tidal fluctuations, creating intertidal zones where water levels rise and fall with the tides. These intertidal zones expose nutrient-rich mudflats, sandbars, and shallow waters during low tide, providing abundant feeding opportunities for migratory birds.
Birds such as shorebirds, waders, and waterfowl thrive in these dynamic environments, foraging on the exposed mudflats for prey like small invertebrates and fish.
But haor regions are not this hospitable for migratory birds year-round, as they experience extensive flooding during the monsoon, with water levels rising rapidly due to heavy rainfall and runoff from surrounding areas. This flooding can inundate large areas of habitat, reducing available foraging and roosting sites for migratory birds.
To put it simply, coastal areas always remain a haven for migratory birds compared to the haor regions. For example, Nijhum Dwip is considered the "busiest airport" for migratory birds.
But Das warns that due to climate change and global warming, these coastal areas in Bangladesh too could eventually become inhospitable for migratory birds if the water levels rise significantly.
"So, of course, climate change remains a cause for concern," he concluded.
