Hipposideros bicolor 131 kHz and Hipposideros bicolor 142 kHz
Common name: Temminck’s Bicolored Roundleaf Bat
The distribution of the Hipposideros bicolor bats. Because they have only recently been identified as separate species, this distribution is for both species combined.
This is Hipposideros bicolor 142 Khz.
Recently, studies of echolocation calls and genetics have shown that what we always believed to one species, Hipposideros bicolor, is actually made up of two species. They are very hard to tell apart, but they differ slightly in the length of their forearms, their noseleaf structure and their echolocation calls. This species has an average echolocation call frequency of 131 kHz, and the other, an average of 142 kHz. At some point, we have to come up with a new name for one of the species, but for now we refer to them as 131 kHz H. bicolor and 142 kHz H. bicolor.
Nose: Like all roundleaf bats the Hipposideros bicolor bats have a very distinctive noseleaf, which in this case is a pinkish grey to dark grey color. The noseleaf is slightly flatter and broader in the 131 kHz bat, and the edges to the the noseleaf of the 142 kHz bats are slightly curved up at the edges, but this is difficult to tell without both of types in the hand for comparison.
Unlike Hipposideros cervinus there are no lateral leaflets, small crescents of skin, on the muzzle.
The noseleaf on the left is that of Hipposideros bicolor 131 kHz and is slightly flatter at the edges than the noseleaf of Hipposideros bicolor 142 kHz on the right
Fur: The bicolor bats get their name because their fur is made up of two colors; the fur is pale at the base and for much of the length, and then brown at the ends. Sometimes the fur will be a reddish-orange color at the tips, usually if the individual has come from a large cave where the build up of ammonia from the bat’s urine bleaches the fur orangish.
Ears: The ears are large between 17 and 21 mm long, and quite rounded until the very tip.
Wings: The wings are a dark brown, broad and rounded, so this species can fly with great manoevurability in the forest.
Tail: Like all Hipposideros, a small tail membrane stretches between the legs, but doesn’t go much beyond the ankle. The tail itself is fully enclosed by the membrane, with maybe just a mm or two of the tail poking out beyond the edge. At each ankle, there is a small rod of cartilage called a calcar, to which the tail membrane is attached, which helps the bat control the position of the membrane in flight.
Size: Hipposideros bicolor 131 kHz is the slightly larger of the two H. bicolor, with an average forearm of about 45 mm and weight of 9 g. The average forearm of Hipposideros bicolor 142 kHz is 43 mm and the average weight 8 g. However, both the forearm lengths and the weights can overlap. So if we have a big bat (forearm greater than 46 mm, we can be sure it is H. bicolor 131 kHz, and if we have a small bat (forearm less than 43 mm) we can be sure it is H. bicolor 142 kHz, but if it is mid-sized (forearm between 43 and 45 mm) it can be impossible to say which is which without recording the echolocation calls.
Ecology
The bicolor bats are forest species and primarily cave dwellers, roosting in large colonies together. They can also be found in the crevices of large boulders.
Where they can be found
Because we have only recently realised there are two species, the current distribution maps may be wrong, as they include both of the two species. It’s possible that one of the species isn’t found everywhere that is listed at the moment. Until we have studied these species across their whole range, we can’t say for sure. For now, their distribution is listed as:
Pakistan and India to Myanmar, Thailand, Loas, Vietnam, Sumatra and Borneo.
