Bumblebee Bat (Craseonycteris thonglongyai)

Description

Kitti's hog-nosed bat (Craseonycteris thonglongyai) is not only the smallest bat in the world, but also the smallest mammal in existence, and the sole living species of the family Craseonycteridae. Its extinction would not only be the loss of an incredibly unique species, but an entire branch of the evolutionary tree would vanish from our planet. Kitti’s hog-nosed bat has long greyish-brown fur on its back, and shorter, paler fur on its underparts. Its common name arises from its flat, fleshy, pig-like muzzle, situated between extremely small eyes concealed by facial hair. Their large and membranous ears, with a long and well-developed tragus, enhance their ability to pinpoint the echoes with which they navigate. Male Kitti’s hog-nosed bats possess a rounded, glandular swelling on the lower portion of the throat; this is either less prominent or completely absent in females.

 Range Description:

This species occurs in Thailand and Myanmar. The type locality in Thailand is Kanchanaburi, Ban Sai Yoke (= Yok), cave near the Forestry Station (14''26'N, 8''51'E). It potentially occurs further south in Myanmar, a genetic study is being undertaken to determine if the species exists in two isolated subpopulations. There are additional limestone caves near the Thai border in Myanmar although these have not been surveyed. Its elevational range is from 0-500 m asl.
Countries: Native:
Myanmar; Thailand

Population:

The total population is restricted to eight caves in Myanmar (Pereira et al. 2006) and 35 in Thailand (Yokubo et al. 2005; Redfield, 2006). The population in Thailand is estimated to be 5,100 individuals and the population has decreased. From 1983 to 1997, there has been a 10% decrease while from 1998 to the present a 14% decrease has been estimated. These figures are not based on the same cave samples, as the species disappeared from some caves and appeared in others and it is not known whether this simply reflects colonies moving from one cave to another (S. Bumrungsri pers. comm.) The population in Myanmar is over 1,500 individuals (P. Bates pers. comm.), all age classes are included although this is likely to be represented by mature individuals as the species matures quickly.
Population Trend: Decreasing

Habitat and Ecology:

This species is always associated with limestone outcrops near rivers and can survive in degraded areas. It always roosts in caves. Weighing around two grams, this tiny bat is reputedly the world's smallest mammal. It is insectivorous and normal foraging range appears to be limited to an area of around 1 km from the roost site (Hutson et al. 2001). This apparently wary bat can be found deep inside small caves, hanging high on the ceiling, suspended by their toes and strong claws. A ‘tendon-locking mechanism’ keeps their claws bent with very little muscular effort, and hanging upside down allows the bat to swiftly take flight from the resting position. Many caves in which Kitti’s hog-nosed bats have been found contain only 10 to 15 individuals, but the average group size is 100, and the maximum is 500. Females give birth to a single young in late April, the dry season, and leave their offspring in the roost whilst they venture out to forage. Kitti’s hog-nosed bats emerge from their caves shortly after sunset, and again just before dawn, when they hunt for brief periods. They search for prey around the tops of teak trees and bamboo clumps, gleaning insects from foliage and seizing small flying insects from the air. Like other bats, the Kitti’s hog-nosed bat can locate prey and navigate through the trees by using echolocation. They emit ultrasonic squeaks that bounce off their surroundings, and the echoes are used to create a mental map of the area, and determine the location of potential prey.
Systems: Terrestrial

Major Threat(s):

The species is affected by disturbance of roosts by religious visits, fertilizer collection and tourism - there has been development of 'show caves' (S. Bumrungsri pers. comm.). There is also the potential for the extraction of limestone which would cause habitat destruction. The smallest mammal in the world, this tiny bat weighs less than 2 grams. Its body is about the size of a large bumblebee, hence the common name “bumblebee bat”. Since it was first described in 1974 this tiny mammal has been disturbed by collectors and tourists wanting to see the world’s smallest mammal. Today the main threats are from burning of the forest areas near the limestone caves in which it lives.

Conservation Actions:

 There is a need for the protection of the cave roosts. A survey of the limestone caves just across the Thai border inside Myanmar is required to determine if the species occurs there. Education of monks to prevent burning of incense is also required (P. Bates pers. comm.) as well as improvement of trans boundary collaboration on conservation of the species along with trans boundary information exchange, and identification and establishment of protected areas (P. Bates pers. comm.).

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