Ha Long leaf-nosed bat – Hipposideros alongensis – Bourret, 1942

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Science name: Hipposideros alongensis – Bourret, 1942

Taxonomic:  Animalia>> Chordata>> Mammalia>> Chiroptera >> Hipposideridae >> alongensis

Species status: Endemic ; IUCN status: VU (Vunerable)

Description: 

Physical Characteristics:
Size and Weight: Hipposideros alongensis is a small bat species, with body lengths ranging between 4 to 6 centimeters and wingspans up to 24 centimeters. It is lightweight, typically weighing between 5 and 10 grams, allowing for agile flight and easy maneuverability.

Body and Fur: This species is covered in soft, dense fur, with most individuals displaying dark brown or reddish-brown coats. The coloration provides effective camouflage within its natural habitat, blending with the dark caves and forest environments where it roosts and forages.

Nose and Echolocation: One of the most distinctive features of Hipposideros alongensis is its leaf-shaped nose, which plays a crucial role in echolocation. The nose is adorned with intricate patterns and folds, specialized for amplifying high-pitched vocalizations that assist the bat in navigating its environment and detecting prey.

Wings and Eyes: The wings of the Ha Long Leaf-nosed Bat are long and slender, with translucent membranes between the elongated fingers. These wings are critical for agile flight in dense forests and caves. The species also has large, round eyes adapted for its nocturnal lifestyle, allowing it to see well in low-light conditions.

Distribution and habitat:

Altitude:
Hipposideros alongensis inhabits elevations ranging from as low as 3 meters to approximately 523 meters above sea level.

Range:
This species is endemic to northeastern Vietnam, particularly within the karst landscapes of Ha Long Bay and Cat Ba archipelago. Two subspecies have been identified: Hipposideros alongensis alongensis on the karst islands of Ha Long Bay and Hipposideros alongensis sungi within fragmented karst forests in mainland northeastern Vietnam. Its distribution is highly restricted, and the species is not recorded outside of this specific region.

Habitat:
Hipposideros alongensis is closely associated with limestone caves, using them for roosting. Its habitat includes a range of environments, from cultivated areas with fruit trees to both primary and secondary forests within karst landscapes. These bats are known to forage along forest trails, streams, and under the canopy of fruit trees, typically flying at heights between 1 to 10 meters above the ground or water. Additionally, it has been observed in mangrove ecosystems.

Behaviour and ecology: 

Social Structure:
Hipposideros alongensis is a social species, forming large colonies in limestone caves. Colonies can consist of up to 500 individuals, although many of these colonies have been in decline due to habitat disturbances. Within the colony, bats roost on cave walls or ceilings, hanging upside down using their sharp claws.

Feeding Habits:
This species is insectivorous, preying primarily on insects such as beetles, moths, and flies. It uses its advanced echolocation abilities to detect and capture insects mid-flight. These bats are important in controlling insect populations, contributing to the ecological balance of their habitat.

Reproduction:
The breeding season of Hipposideros alongensis typically occurs from April to June. Females give birth to a single offspring, which they nurse and care for until the young are old enough to fly and forage independently. The species can live up to 15-20 years in the wild, with reproduction ensuring the continuation of colonies despite external pressures.

Conservation and status: 

IUCN Red List Category and Criteria:
Hipposideros alongensis is listed as Vulnerable under criteria C2a(i), due to its restricted range and a declining population estimated to be fewer than 10,000 individuals. The largest colonies, once numbering around 500 individuals, have dramatically declined to fewer than 200 in some cases, with ongoing declines observed since 2008.

Population Trend:
The population of Hipposideros alongensis is decreasing, with an estimated 9,000 mature individuals remaining. The species has experienced significant declines due to disturbances in its roosting and foraging habitats.

Threats:
The primary threats to Hipposideros alongensis include habitat destruction caused by limestone quarrying, tourism, and deforestation. Human disturbances in caves, where the bats roost, and the loss of forested foraging grounds have greatly impacted the population. The use of pesticides in agricultural areas also poses indirect threats by reducing insect prey availability.

Conservation Actions:
While some populations of Hipposideros alongensis are found within protected areas, such as the Cat Ba National Park, more targeted conservation efforts are required. Protecting limestone caves and surrounding forests from human activity and raising awareness about the importance of preserving bat habitats are critical to ensuring the species’ survival.