How to identify pipistrelles from other European species The presence of a post-calcarial lobe indicates that the species is either a pipistrelle (Pipistrellus) or a serotine (Eptesicus). The post-calcarial lobe is essentially a mebranous lobe on the posterior of the calcal (right - arrowed). Serotines have a greater forearm than pipistrelles so if the forearm is greater than 38mm it's a serotine, and less than 38mm it's a pipistrelle. In the UK and Ireland, that just leaves Nathusius' pipistrelle, the common pipistrelle and the soprano pipistrelle. |
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Morphological meaurements The most important measurements to take to separate Nathusius' pipistrelle from the common and soprano pipistrelle are the length of the forearm (A) and the length of the 5th digit without the wrist (B). It's much easier to use some dial calipers to do this. The forearm is easier to take when the wings are folded up against the bats side. A general guide is to calculate the ratio between the lenght of the forearm and the 5th digit (i.e. 5th digit divided by forearm). If the resulting value is greater than 1.25 it's usually a Nathusius' pipistrelle. |
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The Table below show the data taken from a sample of pipistrelle bats in Northern Ireland and south-west England. The first number in italics is the median value, the values in parenthesis are the range, and the last figure in square brackets and in bold are the number of individuals. Notice that the median for Nathusius' pipistrelle is higher than than for the other two species. However, there is some overlap. | |||||||||||||||||||||
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Wing venation Another method of identifying the species of pipistrelle, based on the pattern of wing venation, has been put forward by von Helversen & Holderied (2003). The diagram on the right shows the 'cells' that are used to separate each species. The key cell is the one that stretches from the elbow to two-thirds of the way down the 5th digit (shaded). In Nathusius' pipistrelles, this cell is divided halfway, whereas in the other species of pipistrelle it remains a single, unbroken cell. |