The Pygmy Swiftlet, scientifically known as Collocalia troglodytes, is a tiny bird species that belongs to the swiftlet family. These birds live in caves and other dark areas, where they build their nests with their saliva.
Despite their small size, they are skilled flyers and are capable of catching insects in mid-air. In this article, we will explore the identification, plumages, molts, and similar species of the Pygmy Swiftlet.
Identification
Field Identification
The Pygmy Swiftlet measures only 9-10 cm in length and has a wingspan of around 16-17 cm. These birds are small and compact, with a slightly curved wingspan, which gives them a distinctive look.
They have dark grey-brownish feathers on the upper parts of their bodies, and lighter, paler grey feathers on their underparts.
Similar Species
One of the birds that can be confused with the Pygmy Swiftlet is the Uniform Swiftlet, which is found in the same range. The Uniform Swiftlet is slightly larger than the Pygmy Swiftlet and has a more uniform color, a paler throat, and a more square tail.
Plumages
The Pygmy Swiftlet is sexually monomorphic, meaning that the males and females are identical in plumage. They have a plain plumage pattern, with no distinctive or bright colors.
However, some variation in the color of their feathers can be seen in birds from different populations.
Molts
The Pygmy Swiftlet undergoes two molts every year, which helps them to maintain their plumage and replace feathers that have become worn or damaged. The pre-basic molt takes place in the late summer or early fall, and the pre-alternate molt occurs in the late winter or early spring.
During the pre-basic molt, the Pygmy Swiftlet replaces all of its feathers, including the flight feathers. During the pre-alternate molt, the birds replace their body feathers, but not their flight feathers.
This allows them to maintain good flight capabilities throughout the year while still keeping their feathers looking good.
Similar Species
The Pygmy Swiftlet is very similar in appearance and behavior to other swiftlets such as the Uniform Swiftlet. These birds are very hard to distinguish from one another without close examination.
To identify and differentiate between these birds, it requires keen observation of body size, color, and plumage details. Another similar species to the Pygmy Swiftlet is the Philippine Swiftlet.
These birds have lighter feathers on their underparts than the Pygmy Swiftlet, and a dark brown patch on their rump. They share the same feeding habitat, similar to Pygmy Swiftlets.
Conclusion
The Pygmy Swiftlet is a small, compact bird species that is expertly adapted to its habitat in caves and other dark areas. Its plain plumage and tiny size make it quite tricky to distinguish from other similar swiftlet species.
Despite being unremarkable in appearance, the Pygmy Swiftlet is remarkable in its ability to catch insects mid-air and navigate its dark home with ease. By understanding the key identification features and molts of the Pygmy Swiftlet, bird enthusiasts can appreciate the subtle beauty of these small birds.
Systematics History
The Pygmy Swiftlet, Collocalia troglodytes, has a complex taxonomic history that includes several changes in its scientific classification. Initially, it was considered a subspecies of the Uniform Swiftlet (Collocalia vanikorensis), but later research showed that it was a distinct species.
The Pygmy Swiftlet belongs to the Apodidae family and is part of the Collocalia genus, which includes other swiftlet species.
Geographic Variation
The Pygmy Swiftlet’s geographic range includes several countries in Southeast Asia and the western Pacific. These birds are found in the Philippines, Malaysia, Indonesia, Micronesia, the Solomon Islands, and Papua New Guinea.
They typically inhabit limestone caves, rocky cliffs, and crevices in buildings, and can sometimes be found in open woodland areas.
Subspecies
The Pygmy Swiftlet is divided into several subspecies, which have different characteristics and geographic ranges. There are currently nine recognized subspecies of Pygmy Swiftlets, according to the International Ornithological Congress (IOC).
1. C.
t. atrata: This subspecies is found in the Andaman Islands and some regions of southern Thailand.
It has dark grey-brown feathers that are paler on the underparts. 2.
C. t.
buergersi: This subspecies is found in the northern Philippines and is slightly larger than other subspecies. It has relatively pale feathers on its underparts, and the tail is more squared-off than other subspecies.
3. C.
t. kordoana: This subspecies is found in the Mima Mounds area of northeastern Papua New Guinea.
It has a dark grey-brown plumage, and the feathers on its underparts are slightly lighter. 4.
C. t.
lepidopygialis: This subspecies is found in the Soela group and other islands in the southern Moluccas of Indonesia. It has a dark grey-brown plumage and is smaller than other subspecies.
5. C.
t. leisleri: This subspecies is found in the Wallacea region of Indonesia and is notably smaller than other subspecies.
It has a dark grey-brown plumage and pale feathers on its underparts. 6.
C. t.
palawanensis: This subspecies is found in Palawan Island in the Philippines and has dark grey-brown feathers that are paler on its underparts. 7.
C. t.
spilura: This subspecies is found in the Babar and Tanimbar islands of Indonesia. It has a dark grey-brown plumage and pale feathers on its underparts.
8. C.
t. troglodytes: This subspecies is found throughout Malaysia, Thailand, and Indonesia and is the most widespread of all subspecies.
It has a dark grey-brown plumage and pale feathers on its underparts. 9.
C. t.
wallacii: This subspecies is found in the Waigeo Island of Indonesia and has a dark grey-brown plumage and pale feathers on its underparts.
Related Species
The Pygmy Swiftlet is part of the Collocalia genus, which includes other swiftlet species. These birds are similar in appearance, but have different characteristics and behaviors.
Some of the closely related species to the Pygmy Swiftlet include:
1. Uniform Swiftlet (Collocalia vanikorensis): This species is found in Southeast Asia and Australia and is slightly larger than the Pygmy Swiftlet.
Its plumage is pale brownish-grey, and it has a more squared tail. 2.
Glossy Swiftlet (Collocalia esculenta): This species is found throughout Southeast Asia and the Pacific and is slightly larger than the Pygmy Swiftlet. Its plumage is dark grey-brown, and it has a more rounded tail.
3. Mountain Swiftlet (Collocalia linchi): This species is found in Southeast Asia and is slightly larger than the Pygmy Swiftlet.
Its plumage is dark grey-brown, and it has a more squared tail.
Historical Changes to Distribution
The Pygmy Swiftlet’s distribution has changed over the years due to various factors, including human activity and climate change. For example, deforestation and urbanization have led to the destruction of the bird’s natural habitats, which has affected their populations.
Climate change has also caused changes in distribution patterns, as birds may migrate to new locations to find suitable breeding and feeding habitats. In addition, the Pygmy Swiftlet’s distribution may be affected by the distribution of its prey.
These birds feed on small insects and require a steady supply of food to survive. Changes in the distribution of insects may lead to changes in the Pygmy Swiftlets distribution, as birds may need to move to new areas to find sufficient food.
Conclusion
The Pygmy Swiftlet is a unique bird species that has undergone various taxonomic changes over the years. Understanding the different subspecies and related species can help us appreciate the diversity of bird species in Southeast Asia and the Pacific.
The Pygmy Swiftlet’s distribution is dynamic and may be affected by various factors such as human activity and climate change, which may impact the bird’s populations in the future.
Habitat
The Pygmy Swiftlet is a bird species that inhabits a variety of habitats, but most commonly, it is found in limestone caves, rocky cliffs, and crevices in buildings. These birds prefer dark areas, which mimic their natural habitat in caves.
They can sometimes be found in open woodland areas, but their requirement of dark places is a must for their survival. Significantly, Pygmy Swiftlets have a particular preference for living in large groups, and they tend to flock together in colonies containing thousands of individuals.
These colonies are noisy environments, with birds constantly chattering and calling vociferously.
Movements and Migration
Pygmy Swiftlets are not known to migrate long distances, but they do make small-scale movements throughout their range during certain periods of the year. These movements are typically related to breeding and food availability.
Breeding movements: During breeding, Pygmy Swiftlets may move to new locations to find suitable breeding habitats that provide a sufficient supply of food and nesting sites. When these birds are breeding, they are known to be residents.
Food movements: Pygmy Swiftlets move to follow their preferred food sources. Due to their habit of feeding on insects in flight, these birds are known to follow swarms of flying insects across different habitats.
It is worth noting that the Pygmy Swiftlet is a weak flier, and as such, it cannot undertake extensive flight movements. It commonly feeds, breeds, and roosts close to its primary habitat.
Conservation
The Pygmy Swiftlet is not considered a threatened species by the IUCN Red List of Threatened Species. This bird species is adaptable, and it can colonize new habitats as long as its primary requirements are met.
Nevertheless, like many bird species, the Pygmy Swiftlet faces multiple threats, with the most significant being habitat loss. These birds are reliant on caves, cliffs, and crevices for nesting and roosting, and human activity, such as deforestation and urbanization, is destroying their natural breeding and feeding habitats.
Further, these birds may also face competition for food resources from invasive species such as rats or bats. To protect the Pygmy Swiftlet, conservation efforts must focus on maintaining and restoring suitable habitats.
This could involve establishing protected areas or habitat management practices that limit human disturbance and protect these birds habitats. Active conservation measures to avoid excessive capture must be ensured as there is also a demand for Pygmy swiftlets in the wild bird trade, where they are caught and traded as pets or for medicinal purposes.
Conclusion
To sum up, Pygmy Swiftlets are residents in areas which they choose to live and breed, they mostly flock together in large colonies where they establish noises that announce their presence. Their choice of habitat mainly consists of natural dark areas such as caves where they can easily feed and breed.
While Pygmy Swiftlets undertake small-scale movements as they follow their preferred food sources, they are not known to undertake extensive migratory movements. However, they face a significant threat due to habitat loss and higher demand for their capture in the wild bird trade.
Conserving their habitat is vital to ensure the future of this bird species.
Diet and Foraging
Feeding
Pygmy Swiftlets are aerial insectivores which means they feed on insects while airborne. They are skilled fliers and take advantage of their small size and agility to hunt insects that are on the wing.
Their short wings and forked tails make them agile in the air, and they can capture their prey in flight.
Diet
The primary diet of Pygmy Swiftlets is insects such as flies, ants, mosquitoes, and other small flying insects. These birds feed mainly on insects that are found around caves and other dark places, where they nest and roost.
They are sometimes known to feed alongside other swiftlet species, such as Glossy Swiftlets, in mixed feeding flocks.
Metabolism and Temperature Regulation
Pygmy Swiftlets have a high metabolic rate, which helps them to maintain their body temperature. Their small size and rapid metabolic rate help them to regulate their body temperature, even in cool environments.
These birds also have specialized plumage that regulates their internal temperature in response to external factors such as heat or cold.
Sounds and Vocal Behavior
Vocalization
Pygmy Swiftlets are vocal birds, and they are known for their distinctive calls that are audible in their breeding colonies. These calls are primarily used for communication within the colonies, and they play an essential role in the social organization of the birds.
The calls of Pygmy Swiftlets are high-pitched, short chirping sounds that are repeated frequently. These sounds are made by the birds’ syrinx, which is located at the base of the trachea and produces sounds as air passes through it.
The calls of Pygmy Swiftlets can be quite loud, and they can echo through the caves or cliffs where the birds live. Pygmy Swiftlets also produce a variety of courtship calls, which are used during the breeding season to attract mates.
These calls include high-pitched trills and twittering sounds, which are performed by both males and females. In addition to vocalizations, Pygmy Swiftlets also use visual cues to communicate.
They have distinctive body postures and displays that are used during courtship and other social interactions.
Conclusion
In conclusion, Pygmy Swiftlets are birds specialized in aerial insectivore feeding upon air-born insects. They have high metabolic rates that are adapted to regulate their internal body temperature in their small bodies.
The birds are social animals, nesting and roosting in colonies where they have distinctive calls that echoily resound throughout their habitat. The calls are an important source of communication that plays a significant role in the social organization of the birds.
Behavior
Locomotion
Pygmy Swiftlets are skilled fliers, and their flying skills are among the most remarkable characteristics of this bird species. They are known for their short, curved wings, and forked tails that make it easier for them to maneuver and catch insects in the air.
They have a high level of agility, which they use to navigate through the dark, cluttered environments where they live. The birds use echolocation skills to navigate successfully while feeding and flying in dimly lit spaces.
Self Maintenance
Pygmy Swiftlets, like most birds, are fastidious self-groomers and spend a considerable amount of time preening their feathers. They use their bills to clean their feathers, remove dirt, and remove ectoparasites that may be attached to their feathers.
Agonistic behavior
Being social, Pygmy Swiftlets have a complex social structure within their colonies, which leads to various forms of aggressive behavior. They may use a series of vocalizations, displays, and actions to establish social hierarchies.
Milder conflicts are solved by swinging their heads or necks and chattering, and more severe disputes can result in pursuing or physically attacking the opponent.
Sexual behavior
During the breeding season, Pygmy Swiftlets engage in courtship behavior similar to other bird species. They use displays, vocalizations, and physical gestures to attract potential mates.
They also form strong pair bonds, with some of the couples staying together for several breeding seasons.
Breeding
Pygmy Swiftlets are colonial nesters, which means that they breed in large groups in the same location.
Breeding colonies can contain thousands of birds, and they usually occupy the same nesting site year after year.
The breeding season varies depending on the location and subspecies, but it typically takes place during the warmer months of the year. When breeding starts, the colony becomes noisy and crowded as birds compete for nesting locations and mates.
The Pygmy Swiftlet constructs and maintains its nest, which is typically made up of spit which it cements to a vertical surface. These nests may be round, half-saucer-shaped, or cup-like depending on the location.
However, all can support one or multiple eggs.
Demography and Populations
The global population size of the Pygmy Swiftlet is currently unknown. However, in general, their populations are relatively stable.
The birds ability to colonize new habitats and large colonies of breeding birds make them generally less vulnerable to changes in habitat or hunting in the wild. However, as Pygmy Swiftlets habitats are being threatened by human activities such as deforestation, urbanization, among others affects their populations.
In addition, the significant ecological effects of the destruction of their natural habitatswhich often contain landmarks and significant historical sitesare devastating entire ecosystems. Thus, there is a call to preserve the populations and habitats of the Pygmy Swiftlet and other bird species to maintain the balance in the ecosystem.
Conclusion
To summarize, Pygmy Swiftlets are social birds that live in large colonies where they engage in various social behaviors such as vocalizations, displays, and physical gestures. They are skilled fliers, able to navigate dimly lit caves and crevices in search of insects to feed.
The Pygmy Swiftlet breeding season usually takes place during the warmer months of the year, and it constructs its nest out of spit, which it cements to a vertical surface. The global population size