created July 2oo8
Pipistrellus nathusii (Keysering & Blasius 1839)
Nathusius’ pipistrelle is a rarely recorded bat in Great Britain and Ireland. Nathusius’ pipistrelles a small species found from western Europe to Asia Minor. To date, however, there have only been about 410 records in the UK . Click here for Jon Russ’ distribution map
We have yet Bedfordshire to get a Nathusius in thw hand, but thanks to Nick Tribe of the Leicestershire bat group have a good idea of what to look for.
In September 2009 we did get a chance to see one first hand, when we had a chance to see this Nathusius in care with the Herts and Middlesex group.
As Jon Russ says
“Nathusius’ pipistrelle is a small species in comparison to other UK and Irish species. The upper fur is longer and shaggier than that of soprano and common pipistrelles, occasionally with pale frosted tips, but generally mid-brown. The under fur distinctly pale. The face, ears and membranes generally dark. Ears are medium sized and rounded – slightly longer than broad withal tragus that has a distinctly blunt rounded tip, about four times as long as broad and curved forward; The calcar reaches about half way to tail and a distinct post-calcarial lobe is present. The thumb has a claw that is equal to or greater than the width of closed wrist. The dorsal surface of the tail membrane is well haired on the basal half and beside the tibia. The fur on the underside of the tail membrane sometimes extends obviously along forearm to wrist ( based on Greenaway & Hutson, 1990).
A general guide is to calculate the ratio between the length 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. “
What was most obvious was how shaggy it’s fur was, the shape of its muzzle and the fact that the fur covered the tail membrane
Until recently we had only one confirmed record dating back to 2005, but had six records in 2007. Five of the six were found over water These were widely spaced which is not surprising as these bats are known to cover long distances.
In May 2010 we got a very clear recording of a Nathusius at Priory Country Park. This is the third time we have heard Nathusius here . Interestingly the other two records were in September.
Pipistrelles have a distinctive way of flying and are the bats you are most likely to see, They have a swooping , fluttering flight and often fly in circles following the same route over and over again,but you can’t separate the three species on the basis of flight pattern.
Things get easier if you have a bat detector but it is still not straightforward. Nathusius’ Pipistrelle are not the easiest bats to identify and we are grateful to Jon Russ for his help in confirming recordings. A rule of thumb is that if the peak frequency is below 40KHz it might be a Nathusius , but might not be, and the social calls are even worse to disentangle.
For more information on identifying Nathusius calls