An extraordinary flight

n their annual ritual, birds from colder regions have started arriving in Nepal, making our land more colorful with their varied plumages. It’s well known that birds travel to warmer climates in winter and back to cooler climates in summer. The lack of important resources like food and shelter drive them to warmth in winter, while the competition for the same motivates them to go back to cooler regions in summer. Nepal hosts about 150 species of migratory birds during winter, and about 60 in summer. The birds that come in summer lay eggs and raise their young in Nepal, while the opposite is true for birds that visit in winter.
 

Every year, migratory birds traverse almost the same routes. Whether their behavior is genetically motivated or if there are some conscious decisions behind it are subjects of study for ornithologists. Migratory birds use a variety of ways to navigate, many of which aren’t fully understood yet.

A lot of their behavior is genetic: birds kept in captivity are known to show restlessness, overfeed, and generally move towards the right direction when it’s time to migrate. Birds are also supposed to have an internal compass that helps them detect directions according to the Earth’s magnetic compass.

At the same time, birds have also have been known to learn migration: they use landmarks like hills, rives, etc, or the night skies, to navigate, which indicate intelligent processing of information. Birds that migrate by night navigate with the help of stars and moon.

Jyotindra Thakuri, Conservation Officer at Bird Conservation Nepal, informs that the birds’ orientation is disturbed by atmospheric elements like clouds, and ducks that migrate by night are known to stop on cloudy or foggy nights.

Conversely, birds that migrate by day navigation do so with the help of sunlight and landmarks. Some diurnal immigrants to Nepal include step eagles, peregrine falcons, and demoiselle cranes. These birds are known to memorize landmarks like hills, rivers, etc. When landmarks change due to natural processes, like erosion, etc, or human processes like construction of new cities, it confuses birds.

Migratory birds show other indicators of learning migration. While a novice migratory bird may get lost, experienced birds can judge things like directions and wind drift better. They pass on their skills to younger ones, proving that learned knowledge isn’t just the domain of human beings.

Some birds also get lost and turn up miles away from their destination, proving that migration is’'t entirely an intuitive process. Jyotindra informs that Nepal has recorded some vagrant birds, like the rare Black-Necked Crane, which normally migrates to Tibet, India and Bhutan. And at other times, birds just forget to migrate back to their homeland in summer after they have spent the winter in Nepal. Surprisingly, their body adapts to the climate of the Nepali summer, which is warmer than the summers of their homeland.

The amount of stopovers a bird makes varies according to the species. Bigger birds like bar-headed goose can cross the entire journey from Siberia in two days, stopping only twice on the way. Smaller birds and ducks stop many times on the way and take a month or more on the journey.

The European widgeon is among birds that fly the farthest to reach Nepal, coming to Nepal from the remote parts of Western Europe. Birds gain the energy for these remarkable flights through voracious feeding before their flight. Birds that don’t stop over especially require considerable stores of energy. They eat so much before flights that the extra fat they put on may even double their weight. By the time they arrive at their destination, they will have lost most of their extra fat.

Lack of food and energy isn’t the only thing that these voyagers have to contend with. Their flight is also fraught with dangers to their life.

“Birds of prey like golden eagles and falcons routinely attack smaller ones like demoiselles,” says Jyotindra, “and reaching their homeland safely is uncertain for these little birds.”

The concept of “homeland” for these migratory birds is vague, because wintering birds stay in Nepal for half the year, from October to April. Nepal is as much their home as their summering ground in Northern Asia or Europe. And yet, many of these birds, like Siberian ducks, are named after northern regions like Siberia or Mongolia. “They are named after areas where they were first spotted and recorded,” informs Jyotindra.

Some varieties of the Lesser Cuckoo, which come over to Nepal from Africa to lay their eggs and raise their young, are identified as African for the same reason—when it could be reasoned that Nepal is more their home because here is where they raise their young. Nepal is the Lesser Cuckoo’s summering ground, just like Siberia is for the birds that come to Nepal in winter. 

Migratory birds in Nepal mostly head towards the wetlands, though some of them also like to live in forests and farmlands. Wherever they go, the birds have important ecological functions to fill in the cycle of nature.

“Birds are an indicator of environmental health,” says Jyotindra. “The presence of migratory birds indicates that our environment contains the resources required to sustain them.”

The yearly arrival of birds in Nepal proves that it is a haven not just for human beings but also for these feathered beauties. It’s that time of the year again when we enjoy lively visitors from distant lands. And this year, we won’t just enjoy their beauty but also respect the hardships that they go through to reach our Himalayan land.

Some facts about migrating birds:

·         The speed of migrating birds varies from 30 km/hr for small birds, like hummingbirds, to 100 km/hr for larger ones, like geese.

·         Bigger birds can fly as far as 800 kilometers without stopping. This enables birds like the Bar-Headed Goose to complete the entire journey in 2-3 days.

·         Birds may fly as low as 500 meters and as high as 9,000 meters above ground.

·         Many migratory birds spend a large part of their lives flying. The Arctic Tern flies to the Antarctic region in winter and flies back to the Arctic region in summer to lay eggs and raise its young. It spends up to eight months in flight, crossing the Earth twice every year.