The inland broad-nosed bat (Scotorepens balstoni) is a species of vesper bat. They are endemic to Australia and widespread throughout the inland, especially in arid and semi-arid regions. This insectivorous microbat, measuring in length, roosts in tree hollows during the day and forages over woodland and water at night.
Description
The inland broad-nosed bat is a moderate-sized species of microbat. It features a characteristic broad square-shaped muzzle when viewed from above that is formed by swollen, glandular pads. The fur colour of the species can vary from dark brown to a pale sand colour, with light grey-brown on the back and pale brown on the belly being most common . This species along with other broad-nosed bats have short slender ears, small eyes, a tail enclosed in the uropatagium membrane and only one upper incisor on each side. Unique to male inland broad-nosed bats are the numerous spines on the glans penis, with up to 22 spines on the head in two long rows. Body measurements, especially forearm length, along with distribution are useful in identifying the species. The species can also be identified by its short tragus of . Male inland broad-nosed bats tend to be slightly smaller than females.
Table 1. Measurements important for identification purposes
The species has characteristic echolocation frequencies of 34.1 - 38.7 kHz in WA and 28 –34 kHz in NSW.
Taxonomy
Scotorepens balstoni (pronounced skoh′-toh-rep′-enz bawl′-stun-ee) translates to mean ‘Balton’s darkness creeper’.
There are several synonyms existing for this species which include: Nycticeius balstoni (Thomas, 1906) Scoteinus balstoni (Thomas, 1906) Nycticeius influatus (Thomas, 1924) Scoteinus influatus (Thomas, 1924) Scoteinus balstoni caprenus
Research evidence indicates that Scotorepens balstoni may be a ‘composite of several distinct species’ creating the need for a ‘comprehensive taxonomic assessment’ of the species. Due to similarities in appearance Scotorepens balstoni is most likely to be confused with the other species of small broad-nosed bats (Scotorepens): S. greyii, S. orion, S. sanborni and S. sp..
Distribution and habitat
Inland broad-nosed bats are distributed widely throughout inland Australia, including arid and semi-arid regions. They are generally not distributed east of the Great Dividing Range.
In Western Australia distribution covers the northern wheatbelt, the south-western interzone, the Murchison region, the Gibson desert and the Great Victoria desert. In the Western Australian rangelands the species shows preference for Mulga woodland, while also choosing to inhabit Salmon Gum/Gimlet and York Gum woodlands. In the semi-arid Mallee region of north-western Victoria inland broad-nosed bats show a preference for open woodland and dryland woodland habitats. Other known occurrences in semi-arid regions in New South Wales are at Willundra Lakes and Kinchega National Park, along with Dangalli in South Australia. In South Australia distribution in arid areas indicates a habitat preference for river red gums following surface drainage systems.
Behaviour
Roost habits
Inland broad-nosed bats prefer to roost in tree hollows, in groups of up to 45 individuals. Roosting also occurs in the roofs of buildings, under metal caps of power poles and in water pipes. They often roost horizontally. The species has been known to share roosts with colonies of south-eastern freetail bats (Mormopterus sp.).
Diet and foraging
Inland broad-nosed bats are described as air-superiority insectivores. In northern distribution areas they are known to eat cockroaches, termites, crickets, cicadas, bugs, beetles, flies, moths and ants. In Victoria their diet consists mostly of beetles, ants, bugs, moths, flies and grasshoppers. They start foraging earlier than most other species, beginning usually just on dusk. Foraging is achieved using echolocation whilst in continuous flight, keeping within 15 metres of the ground, with rapid diversions to pursue prey. Foraging mainly occurs between trees, not going above the tree canopy, as well as at the edges of forests venturing into open areas. Speeds during flight have been measured between . Flight efficiency is a result of the species having a streamlined head shape, silky fur texture and small manoeuvre-enhancing shaped ears.