• Pera Kasemsripitak

Migratory Birds in Thailand

In silhouette against the smooth orange sky, hundreds of black kites rest on the eucalyptus trees. They will glide again when thermal columns form in the morning.

AS THE SUN set over the vast rice paddies in Nakhon Nayok, Thailand, hundreds of black-eared kites perched scattered on dozens of trees, the soft light warming and drying their delicate coat of feathers.

The air was cooling down, dissipating the thermal column the raptors relied on to glide and hunt. Brown, dull, and small, black-eared kites seem like quite an ordinary bird. As golden hour approached, they settled down to rest on an array of branches overlooking the wetlands. Perching for hours on end, they can look sedentary to the spectator. Nothing can be further from the truth. These predatory birds fly over 5000 kilometers every year from Siberia and Mongolia to the tropics, fleeing the intense climate of the north.

After the air cools, birds take a rest on the trees for the night. Here, two black kites are perched on a fallen branch in the swamp, with many more scattered around.

Black-eared Kites, like many migratory bird species, do not stop during their journeys. Food from their stomachs transform into fats stored in their bodies to preserve heat and energy while saving weight for their flight. To maximize their energy efficiency and speed during their journey, they molt to prepare new aerodynamic feathers. Their large wing surface area allows them to make use of thermal columns (pillars of rising hot air from the ground) to stay airborne while minimizing loss of energy from flapping their wings. Furthermore, long migrations aren’t one-day trips. Raptors and other birds use a sleeping technique called ‘unihemispheric slow-wave sleep’ (USWS), which allows them to fly with their eyes closed. One side of the brain enters deep sleep with the eye corresponding to this side half-closed, while the other eye remains fully open for the flight. They essentially have 2 pilots working in shifts to keep them aloft. These adaptations are crucial for their long-distance flights.

Chai, a zoologist studying Bird, Mammal, Amphibian, and Reptile populations observed the scene of the gathering from afar. “These hawks are quite weak after their long flights,” he said, as a Jungle Crow chased a Black-eared kite overhead. “These crows can actually kill the raptors”.

In Pak Phli, Nakorn Nayok, amongst the semiarid ranchland and scrub, is a public wildlife preserve just 26 km south of Khao Yai National Park. The wet and uneven conditions make it perfect for waders and hawks to hunt, attracting tens of thousands of migratory birds every year. Snakes, fish, frogs, and lizards make a perfect meal for the wading birds, increasing the chances of spotting a rare or endangered species in the region. Black-winged stilts, painted storks, cormorants, herons, and even oriental darters, which were rarely seen, are now commonly found here during wintertime. The plethora of Bird Species is a true spectacle to any observer - whether an amateur watching for pleasure or a professional collecting scientific data. With increased attention towards these flying gems, conservation efforts are bringing them back to residential areas and cities. If humans accrued equal wisdom to these birds’ instincts, maybe they’ll stay around for longer for everyone to enjoy.

Displayed below are photographs of the remarkable nature in the area.

Displayed in front of our fiery sun is a pair of black kites in silhouette. During their species’ bi-annual migration, this very sun emits polarized light rays which guides the birds to their destinations.

A large flock of black-winged stilts takes off from the wetlands early in the morning to look for food.

A flock of painted storks is seen flying in tandem with an airplane under a magnificent sunset. The “V” shape of their flying formation conserves their energy in long flights due to the reduced air resistance on the birds flying at the back of the formation. The birds take turns flying in front and fall back when they get tired, balancing the efficiency of the group.

In solitude, this cattle egret was observed eyeing prey in a swamp. This species of heron usually lives in symbiosis with livestock to feed, hence its name.

The biodiversity within this swamp ecosystem is stunning; over 50 species were observed within one day, most of which were birds. Depicted here are 4 different species of birds; black kites, seen on the trees, a little cormorant, seen near the bottom left corner, cattle egrets, standing on a rotting stump, and a grey heron standing next to the cattle egrets.