World Migratory Bird day 2024: Protect Insects, Protect Birds


As the birds take to the azure skies and journey across distant lands, oceans, and even continents, they bring tidings of changing seasons from their homelands and balance to the waiting ecosystems.

The natural process of migration occurs when birds leave their native lands during unfavourable conditions to find favourable grounds for better survival. Annually, thousands of flocks of migratory birds take flight to escape the onset of winter in their native lands, to warmer parts of the world via flyways or migratory routes, where more food resources, warmer conditions, and better chances for survival prevail, where they will eventually spend their winter. Since some flyways are long and aimed at distant lands, many birds stop-by at several warmer ecosystems for rest and feeding too.

What Makes Migration Possible For Them?

Migratory birds possess perfect morphological and physiological adaptations to migrate. Most of these birds have a higher aspect ratio and more pointed wings compared to their non-migratory neighbours, stronger pectoral muscle fibres, more red blood cells to withstand the low levels of O2 at high altitudes, and many even have different forms of hemoglobin with differential efficiencies for O2 transportation. These birds store energy mainly in the form of fat, since it releases more energy upon hydrolysis. There is a dramatic increase in appetite and feeding seen in migratory birds too, a behavior termed ‘hyperphagia’ that is seen a few weeks prior to the onset of seasonal change. With this, the food consumed is stored as fat, increasing the bird’s metabolic fuel reserves. Many shorebirds and songbirds forage during the day and migrate during the night, possibly for protection from predators and dehydration. Migratory birds are known to use day lengths and declining temperatures to sense changing seasons, while they follow specific flyways with the help of the sun’s orientation, stars, and the Earth’s geomagnetic field.

Many reduce the air resistance and the number of wing beats to glide, thus reducing energy expenditure. A flock of geese fly in a ‘V’ shape to reduce drag for this reason too. Many species use the same flyways and stopover sites during every migration, hinting at navigation skills and spatial memory capacities in these birds.

Wingspan of Arctic Terns who migrate from the Arctic Circle to the Antarctic Circle yearly

Migratory birds in Sri Lanka

As a beautiful, tropical island with lush greenery and biodiversity-enriched ecosystems, Sri Lanka is one of the main stopovers and wintering grounds for many bird species from all over the world. Migrants include Egrets, Wagtails, Plovers, Ruddy Turnstone, Black-winged Stilt, Glossy Ibis, Common Redshank, Pin-tailed Snipe, Little Stint, Eurasian Curlew, and Greater Flamingo.

   Fig. 2: Common Redshank

   Fig. 3: Black-winged Stilt

Fig. 4: Lesser Sand Plover

As the southern tip of the Central-Asian flyway, flocks following the flyway route reach our island through the western route, eastern route or Andaman route by mid-August and return to their native lands by the end of April the following to breed.

The main bird sanctuary in Sri Lanka is Kumana National Park, an important roosting and breeding site for migratory birds. Several hundred flamingos are sighted in Bundala National Park and Mannar Lagoon during the migratory season, due to the lagoons’ abundance of food resources. More common migrants, such as the Asian Paradise Flycatcher (Sudu-redi hora) and the Indian Pitta (Avichchiya), take temporary residence in home gardens.

Fig 6: Asian Paradise Flycatcher

Fig 7: Indian Pitta 

These migratory corridors allow birds to rest along their journey towards other lands or winter there until they could fly back home during favourable seasons, connecting ecosystems and biodiversity across the world.

The Importance of Migratory Birds

The second Saturday of May is dedicated to these migratory birds, given their importance and crucial role in maintaining nature’s balance. These birds are the bearers of dispersing agents, allowing seed and spore dispersal in diverse habitats. This results in increased chances for a plant species’ survival, reproduction, colonization, and reforestation. Migratory birds participate in nutrient cycling, which is vital for an ecosystem’s functioning. They are also both predators and prey, completing the complex food webs that maintain the balance of the ecosystems they get involved in. The migratory bird species contribute to the maintenance of biodiversity since they move to regions with better chances for survival until their native land assumes favourable climatic conditions again. The insect populations that these birds feast on are kept under control upon their yearly visits, thus controlling pest populations as well.


World Migratory Bird Day 2024

This year’s theme for World Migratory Bird Day, which falls on May 11, 2024, focuses on the role of insect populations and their importance to these migratory bird species. As important sources of nutrients and energy, insects are most abundant in stopover routes such as wetlands, forests, and agricultural lands, and this allows the birds to rest and refuel before resuming their journey towards favourable grounds, or simply provide the migrants with an abundance of nutrition while they stay. Due to the immense amounts of pesticides, insecticides, and chemical fertilizer used by humans for agricultural activities in the vicinities of these stopover sites, insect populations are rapidly declining. This is affecting the migratory birds’ survival and fitness, their immunity, and reproductive success, reducing the chances for these birds to reach their native grounds again for breeding, given the long distances they have to cover. With this, bird numbers would keep rapidly declining, and with it, all the useful services they render to the ecosystems they join, however temporary, would be lost.

Given the importance of these migratory birds for the functioning and balance of ecosystems, it is important that we protect the ecosystems that these birds are a part of for the conservation of these avian migrants. As the theme for World Migratory Bird Day 2024 highlights, insect populations in the stopovers and wintering grounds have to be left abundant for the migrants. It is our duty to reduce the use of harmful chemicals and fertilizers that destroy non-target insects, use better sustainable pest management methods for pest control in agricultural lands, minimize overuse of land, conserve the main migratory bird hotspots without distorting them with infrastructure and deforestation, and allow nature to take control of the natural processes that are rightfully hers.



    A GUIDE TO THEIR IDENTIFICATION AND STUDY by P N Dayawansa and Mayuri R Wijesinghe
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  4. Migration Window to Nature. Available at: (Accessed: 09 May 2024).
  5. Have Wings, will travel: Avian adaptations for Migration Smithsonian’s National Zoo and Conservation Biology Institute. Available at: (Accessed: 11 May 2024)


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