Bats Chiroptera

click to enlargeTRACKS & SIGNS: Bats roost in a number of locations such as caves, mines, modern and old buildings, bridges, walls, tree holes and rock crevices. In many situations they leave evidence behind, most notably in the form of droppings. Droppings of all bats are small, similar in size to mouse droppings. Mouse droppings, however, are hard and difficult to crush, whereas those produced by bats crumble under slight pressure as they consist of insect fragments. Droppings can occasionally be observed in large numbers under long established roosts in attics, caves and under exit points on buildings. Droppings can often be seen stuck to windows or the walls of houses. In some instances, urine streaks can also be observed. There is some variation in dropping size and consistency, which may give an indication of the species:

 

Variation between species' droppings*
Daubenton's bat Particle size is fine and dropping have a smooth outline. Droppings are about 2mm in diameter and 8-9mm in length.
Natterer's bat Particle size is medium, diameter is about 2.3-3.3mm and length is about 8-11mm.
Whiskered bat Medium particle size, length is about 6-9mm and dropping diameter is about 2.0-2.3mm
Leisler's bat Dropping are about 2.5-3.0mm in diameter and about 6-9mm in length. The particle size is medium.
Nathusius' pipistrelle Particle size fine, diameter 1.5-2.0mm and length 7-9mm. Smooth outline.
Common pipistrelle Particle size fine, diameter 1.5-2.0mm and length 7-9mm. Smooth outline.
Soprano pipistrelle Particle size fine, diameter 1.5-2.0mm and length 7-9mm. Smooth outline.
Brown long-eared bat Particle size medium-coarse. Diameter 2.5-3.0mm and length 8-10mm. Knobbly outline.
*based on Stebbings, R.E. 1993. Which Bat Is It? The Mammal Society, London.

 

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Droppings of bats with those of the house mouse and the brown rat for comparison
A pile of bat droppings underneath the roost exit

 

Some species such as the brown long-eared bat and Natterer's bat use feeding perches to consume insects and these can be identified by the piles of droppings and intact wings of insects. Heaps of long-eared bat droppings in attics do not often contain insect wings.

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A bat roost behind some dislodged plaster on an outside wall
Herald & Underwing wings in a pile of brown long-eared bat droppings
A tree roost
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A building occupied by whiskered bats
A hibernation site for Daubenton's bats
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A roosting brown long-eared bat
The ceiling of an underground dungeon, worn smooth by roosting Daubenton's bats
A 'traditional' roosting site for bats
Urine stains on a window underneath a roost exit

 



© Jon Russ 2001. Text refereed by Angela Ross & Lynne Rendle.

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