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Text and photos by Nick Baker, unless credited to others.
Copyright ゥ Ecology Asia 2024







Horsfield's Flying Squirrel

Fig 1

Fig 2

Fig 3

Fig 4


Family : Sciuridae
Species : Iomys horsfieldii

Head-Body Length : Up to 19 cm
Tail Length : Up to 18 cm
Weight : Up to 165 grams

Play call

Horsfield's Flying Squirrel, or Javanese Flying Squirrel, is a medium-sized flying squirrel which occurs in a range of habitats including primary forest and poor secondary forest.

It is considered to be an adaptable species which may consume a range of seasonal food items, but predominantly fruits. It may occur in areas where fruit trees were once planted by villagers, but which are now abandoned and have reverted to secondary forest.

Contrary to Thorington et al (2012), who suggested the species many now be extinct in Singapore, it is still in fact fairly common in secondary forest in the centre of the main island of Singapore, both in the areas designated as nature reserve and in neighbouring regrowth forest.

This species appears to be fully nocturnal, only emerging from its treehole after nightfall. At such times its presence in the forest can be ascertained by its loud call, which can be heard from some distance. The call is a short, downwardly-inflected bark rather like that of a small dog.
Play call

Its fur is brown on the back, and orange or whitish beneath the gliding membrane or patagium. The tail, which is flattened like a feather, is orange to reddish. Its ears are relatively large, and upward-curving, and there is typically a dark eye ring.

Horsfield's Flying Squirrel occurs in Peninsular Malaysia, Singapore, Sumatra, Java and Borneo. Thorington et al (2012) recognise four subspecies.

Figs 1 and 3 : Typical example of Horsfield's Flying Squirrel from Peninsular Malaysia at an elevation of 1100 metres. This specimen, along with more than 20 others, was attracted to the presence of abundant acorns in an area of forest dominated by oak trees (possibly Quercus gemelliflora).

Fig 2 : This species can glide effortlessly and efficiently for many tens of metres, without significant loss in height.

Fig 4 : Male specimen from Singapore's central forests, consuming a small, soft, pulpy fruit.

References : M10