Top 15 Intriguing Facts About Swiftlets

Swiftlets belong to the Swift family (Apodidae), which is further divided into two main subfamilies: 13 primitive Swiftlet species (Cypseloidinae) and 79 modern Swiftlet species (Apodinae). The scientific name for Swiftlets is derived from a Greek word meaning 'without feet' (apous) due to their extremely short legs, commonly observed as they gracefully soar across the sky rather than perching on the ground.

Swiftlets are among the species spending most of their time in the air, with some, like the common swiftlet, even sleeping and mating while flying. Larger species, such as the white-throated needletail, are among the fastest flyers in the animal kingdom.

These valuable birds are widely distributed in many Southeast Asian countries and regions with tropical and subtropical climates. In Vietnam, the majority of Swiftlet farming is concentrated in provinces in the South, such as Khanh Hoa, Kien Giang, and Binh Thuan. Swiftlets play a crucial economic role, bringing substantial income to local communities.

Swiftlets utilize their own saliva to construct nests, and this saliva exhibits excellent adhesive properties, allowing them to attach nests to various surfaces such as branches, leaves, and even vertical structures like walls, cliffs, and caves.

Typically, the nesting process of Swiftlets occurs as they prepare for the breeding season, unfolding as follows:

• The males call the females to join them for communal living prior to the breeding season. Both genders collaboratively build nests for egg-laying purposes.
• During the breeding phase, the salivary glands of both males and females develop and expand on the sides of their mouths. They start secreting saliva and use their beaks to elongate it into strands. Subsequently, either the male or female employs these strands to weave the nest.
• This process continues consistently for about 45-50 days, with both partners taking turns to forage for food and return to rest in the nest. Typically, the saliva in Swiftlet nests dries within 2-3 hours.
  
• As the time for egg-laying approaches, the weaving and construction of the nest accelerate. The completion of the nest coincides with the onset of the female's egg-laying.

Regarding Size: Swiftlets display considerable size variation due to their extensive variety. The smallest species, known as Pygmy Swiftlet, weighs only around 6g and measures a mere 10cm. On the other end, the largest Swiftlet species, the White-rumped Swiftlet, can weigh up to 190g and reach a length of about 25cm.

Physical Appearance: The most distinctive feature of Swiftlets is their legs. These birds have extremely short legs, nearly invisible to the naked eye, often only noticeable when they pause from flying and cling to surfaces like cliffs or walls. This characteristic leads them to spend most of their lives in flight, seldom landing and walking like many other bird species.
Swiftlets' feathers are typically black or slightly brown, with males and females having a similar appearance. Their bodies are shaped like a lozenge, accompanied by large wingspans that enable graceful and easy flight in the sky. Additionally, this structure aids in hunting prey even while in flight.

Behavior: Swiftlets, with their short but sharp claws, are adept at gripping and clinging to vertical surfaces or challenging terrains such as walls, mountain cliffs, and rock surfaces. They use their saliva to create nests on these vertical surfaces and initiate the breeding process once the nest is complete. This species lives in large flocks, with a considerable number of individuals.

Habitat: Swiftlets predominantly thrive in regions with tropical or temperate monsoon climates. Their diverse habitats include grasslands, mountain crevices, meadows, deserts, urban areas, etc. They are commonly found in elevations higher than sea level, approximately 4000m, and in proximity to water sources.

While we often consume swiftlet nests, the specific swiftlet species may go unnoticed. Across the globe, numerous swiftlet species exist. However, in our country, there are four common groups of swiftlets:

• White Swiftlet: Found exclusively in Southeast Asia, white swiftlets build nests primarily using their saliva, making them more valuable than other species. The white swiftlet, about 13cm in length, has a shorter body than other swiftlet species. It features grayish breast feathers, lighter tail feathers, no white patches on the back, and a round tail.
• Black Swiftlet: Evaluated lower than white swiftlets due to nests containing only saliva and more body feathers. After harvesting, humans employ techniques like soaking, feather separation, freezing, and drying to produce high-quality swiftlet nests.
• Indian Swiftlet: Rated the lowest as their nests consist of approximately half saliva and the remaining portion includes grass, moss, and attached feathers. The nests require additional processing to remove impurities and undergo a drying process to create high-quality swiftlet nests. As the name suggests, these swiftlets are most commonly found in India and Sri Lanka.
• House Swiftlet: Highly valued by breeders for the products obtained, house swiftlets predominantly construct nests using saliva. Depending on the harvesting technique, processing may or may not eliminate impurities. House swiftlets thrive in various locations and prefer environments with temperatures around 28°C.

The breeding season for Swiftlets usually begins from March to mid-April each year. During this time, the male pairs with the female, and both seek a suitable location to build a nest for later egg-laying. Normally, Swiftlets forage during the day and return to the nesting site in the evening around 6 PM. After resting for about an hour, they start secreting saliva to construct the nest.

They continuously build the nest from the evening until 3-4 AM the next day. In the initial phase of nest building, they weave about 12 strands per day, increasing to around 15 strands per day as the breeding season approaches. The nest-building process lasts for approximately 50 days.

Once the nest is complete, both Swiftlets mate to initiate their reproductive process. Typically, Swiftlets mate during the night, between 9-11 PM or 1-3 AM the next morning. They mate 3-4 times a day before laying eggs, approximately 8-10 days later. After the first round of eggs is laid, Swiftlets mate one final time to produce a second batch of eggs, focusing then on caring for their offspring.

During the incubation period, only one parent is involved in this task, while the other forages for food. They often switch roles 4-5 times a day. After about 3 weeks, the eggs will start hatching, giving rise to fledglings. Initially, both parents will forage and return to warm their offspring. As the chicks grow a bit older, the parents will only be responsible for feeding them without the need for warmth.

Devotion: Swifts live in flocks but form monogamous pairs. During the breeding season, the male and female swifts collaborate to build a nest and live together almost their entire lives, only leaving if their nest is threatened or destroyed.

Keen Senses: Swifts possess a highly sensitive sense of smell, quickly detecting even the faintest unfamiliar odors in their surroundings. This explains why they choose nesting sites used by their kind before, as the scent of their flock indicates a safe place.

Never Perching: Unlike many other birds that perch on branches or power lines, swifts simply hang on cliffs or construct nests indoors without ever perching. This behavior is partly due to their weak legs, incapable of supporting their weight. However, their astonishing flying speed, reaching up to 160 km/h, compensates for this limitation. They can fly continuously without feeling tired, covering distances exceeding 50 km daily.

Due to the harsh natural weather conditions, island swiftlet nests often exhibit a rough surface. The rougher and more intensely golden the color, the older the nest. Island swiftlet nests typically manifest as small, round structures with exceptionally rigid and uneven legs – not flat. Since island swiftlet nests adhere to rocky surfaces, the area where the legs contact the nest remains uneven due to the irregularity of the rocks.

In contrast, indoor swiftlet nests showcase an ivory-white hue, are larger, possess more feathers, and feature a smoother surface.

The market value of island swiftlet nests far surpasses that of house swiftlets due to the extremely challenging and strenuous nature of harvesting nests from the wild islands. Conversely, harvesting nests from houses proves relatively straightforward.

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