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Visual Clues for Leisler's Bats

You can also use visual clues to help identify the bat.

Leisler's bats have long but very narrow wings that look quite pointed. They fly high, out in the open usually in fairly straight lines or in big, wide arcs making dives to catch prey in the air. The wings beat deeply and the flight is very fast.

The rhythm of the Leisler's bat call reflects the way they fly. It is regular when they are making wide arcs or straight lines, but then suddenly becomes erratic as dives are made.

Similar species

The following two species have not been confirmed as occurring in Ireland, but are still worth considering, as bat species distributions can gradually change.

Noctule bats look similar to Leisler's bats in flight, as they too have long, narrow wings, but tend to fly higher in the open and perform much steeper dives to catch their prey. Their calls tend to also have lower peak frequencies (see previous page).

There have been some unconfirmed records of possible noctules in Ireland, so if you identify characteristics which seem more like noctule than Leisler's bat then record the bat as "Leisler's unsure".

Serotine bats are recorded in the southern half of England and as far west as Cardiff, but are not thought to occur in Ireland. In flight they often look heavier and darker than Leisler's bats and noctules. They don’t tend to fly as high up which makes them look bigger and their wings are broad. Their wing beats are much more fluttery and shallow and their flight is not as fast. They are much more likely to be making smaller, tighter turns popping in and out of tree cover.

As the serotine tends to make more turns, the rhythm can often be erratic but with a ‘funky’ pattern. Serotines can even land on the ground or on dung to take big insects like beetles.

 

 

 

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Above: Noctules tend to perform steeper swoops than Leisler's bats. If you observe this flight pattern and the call peak frequency is below 22 kHz then record as "Leisler's unsure" (see the previous page for more information on determining the peak frequency).

 

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