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Migratory birds are fascinating creatures that embark on epic journeys spanning continents and defying geographical barriers. It’s a remarkable natural phenomenon observed across the globe. The most interesting fact is that they fly long distances between their wintering and breeding grounds across continents and oceans, unlike other birds. The prominent reason for migration is to escape harsh winter conditions while seeking abundant food sources and suitable nesting locations. As they travel thousands of miles between two grounds, their physical ability, regularity, and navigational skills should be at a truly remarkable level. Pelicans, storks, swifts, flycatchers, orioles, cuckoos, sandpipers, arctic terns, cranes, and shore larks are some migratory species.
There are two types of migrations: long-distance migrations and shorter migrations. Some birds, like Arctic terns, travel between Arctic breeding grounds and the Antarctic each year. Shorter migrations occur as altitudinal migrations: White-tailed Ptarmigan in North America migrates vertically between alpine meadows and lower valleys; latitudinal migrations: European Cuckoos travel from Europe to Africa for the winter; and coastal migrations: shore birds such as sandpipers and plovers migrate along coastlines, stopping at mudflats and beaches.
They undergo extensive preparation for migration, including energy storage through increased food intake and diet changes, organ and muscle adjustment, and mostly for efficient flight. As a specific adaptation, their belly gets larger, and their digestive system automatically shuts down to store energy. This makes their flight more efficient since the productive energy could be used for the flight as a whole. Some species, like the bar-tailed godwit, even undergo drastic changes, like shrinking their digestive systems to enhance flight muscles.
Have you ever thought of the reason behind the patterns created by migratory birds while they fly?

Despite the distance between their breeding and wintering grounds, they have to migrate for the sake of their survival while keeping their physical fitness within an adequate range. Since they should conserve energy gained before the journey and have to save until they reach their destination.
When birds fly in a V-formation, they take advantage of the upwash vortex fields created by the wings of the birds in front. This aerodynamic effect allows them to conserve energy by flying slightly behind and to the side of the bird in front. Each bird benefits from reduced air resistance. The V-formation minimizes the effort required to maintain flight, especially during long-distance migrations.
The V-formation also facilitates communication and orientation among the birds. Birds can visually track the movements of their companions, helping them stay on course during migration. Additionally, communication within the flock is essential for safety and coordination. Birds can signal danger, share information about food sources, and maintain social bonds while flying together.
The Life Cycle
Their life cycle mainly consists of four phases: the breeding phase, migration away from breeding grounds, the overwintering period, and migration back to breeding grounds. During the breeding phase, migratory birds arrive at their breeding grounds in spring. Then they establish their territory by singing and building nests. The female lays and incubates the eggs until they hatch. After the breeding phase, migratory birds embark on their long journeys to their wintering grounds. They seek areas with abundant resources. They settle in their wintering habitats during the overwintering period. These areas provide essential resources during the colder months. As spring approaches, they begin their return journey to enjoy the warm weather in their native grounds. They navigate using celestial cues, the Earth’s magnetic field, and visual landmarks. The return migration is equally impressive, as they find their way back to the same breeding ground where they started.
Conservation
Migratory birds face many threats affecting their declining populations. The loss, degradation, and fragmentation of important migratory habitats is the potentially largest individual threat to them. When considering migratory birds, habitat plays a major role, as most of them are habitat-specific species. They need a quality habitat to build their nests, and it will be a protective habitat for hatchlings. If that habitat is destroyed or disturbed during the breeding season, nests and hatchlings may be lost or abandoned, or productivity may be reduced. Also, biodiversity loss, climate change and pollution make their populations decrease.

It is identified that some of the conservation remedies help increase their number and maintain healthy populations in a significant manner. Habitat restoration and conservation efforts, habitat mitigation, smart project siting, international coordination, climate change research, and habitat change predictions are some of the remedies that can be taken.
There are some service coordinates agreed upon internationally, such as the Trilateral Committee (US-Mexico-Canada), the Ramsar Wetlands Convention, the US-Russia Environment Agreement, the US-China Convention Protocol, and Migratory Bird Conventions with Canada, Mexico, Japan, and Russia, which help with the healthy populations of them.
Written by:
Dinya Hasandi,
1st Year Undergraduate,
Biological Science Stream,
Faculty of Science,
University of Colombo.
References:
- Migration Challenges & Conservation in Birds: Strategies for Safe. . . (2023, October 3). Birdfact. https://birdfact.com/bird-behavior/migration/challenges-and-conservation#:~:text=International%20Conservation%20Efforts%201%20The%20Convention%20on%20Migratory,Ramsar%20. . .%205%20World%20Migratory%20Bird%20Day%20
- Powell, H. (2023, October 2). The Basics of bird migration: how, why, and where. All About Birds. https://www.allaboutbirds.org/news/the-basics-how-why-and-where-of-bird-migration/
- The full annual cycle of migratory birds. (n.d.). Smithsonian’s National Zoo and Conservation Biology Institute. https://nationalzoo.si.edu/migratory-birds/full-annual-cycle-migratory-birds#:~:text=A%20migratory%20bird%E2%80%99s%20annual%20cycle%20can%20be%20divided,live%20in%20different%20habitats%20or%20have%20different%20needs.
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