This last weekend was pretty busy as I went along to Chesire Wildlife Trust's Bat & Moth evening as well as taking a day out at Yorkshire Sculpture Park. On the upside, that makes for quite a few articles. On the downside, that makes for no time in which to write them, especially when you consider that I work part-time as a lecturer and it's enrollment week!
Friday's Bat & Moth evening was pretty nifty, split into a bat watch and walk, as well as an introduction to moths and moth trapping, so I'm going to do a few entries on it in a similar way.
The bat watch & walk was really interesting and informative, though a bit more technical information about the frequency ranges of the bats we were picking up on the bat detectors would have been more helpful -- but you can't have everything. We did an emergence watch and saw quite a few brown long-eared bats (Plecotus auritus) leaving their roosts in one of the older buildings at Delamere. They were really loud at the 43 kHz range on the bat detectors, which is no surprise as their call range is 27-56 kHz. However, it's really worth noting that you'll see these critters before you hear them usually as the detectors only work on their quiet calls up to a distance of 6m, hence their other name, whispering bats. A good daylight indicator of these chaps being around is moth wings under the roost (most favoured moth being the Yellow Underwing) and of course, bat droppings on the wall.
As soon as they left the roost, they immediately headed for the closest tree to feed. They are gleaning feeders, meaning that they eat the insects that alight on leaves and tree bark. Unfortunately, as it was a bit dark and the bats were a bit far away (who'd've thought, eh?) I wasn't able to get any pictures of any bats that evening, however, here's a picture from wikimedia commons of what a brown long-eared bat looks like:
They look far more charismatic as a species when they're moving and not stunned. Bad photos even happen to bats, apparently!
The next bats we fleetingly saw and certainly heard were the pipistrelles. There are two types of pipistrelle -- the common pipistrelle (Pipistrellus pipistrellus) and the soprano pipestrelle (Pipistrellus pygmaeus). The main identifying difference if you're spotting using a detector is that the common pips have a call with most energy at 45kHz, whereas the soprano pips have a higher echolocation call at 55kHz. We also heard a few social calls down in the 20kHz range. Social calls are the bat world's version of a male bat calling out "hey, ladies!", especially when you bear in mind that bats have harems.
The calls of these bats are interesting to listen to as you can actually hear them hunting. When they dive to catch an insect, it sounds like someone has just blown a raspberry. When it stops, chances are that the bat is having dinner.
I'm fairly certain I also heard a Natterer (Myotis nattereri), though as the pips were around at the time and were being pretty loud, it was hard to tell. However, it wasn't the same sound and the frequency went as high as 70kHz before suddenly stopping rather than fading out. The lovely folks from the local bat group seemed to think it was a good possibility though.
Either way, they were amazing to watch and to hear. It's just a shame their body-clocks are so antisocial!
Friday's Bat & Moth evening was pretty nifty, split into a bat watch and walk, as well as an introduction to moths and moth trapping, so I'm going to do a few entries on it in a similar way.
The bat watch & walk was really interesting and informative, though a bit more technical information about the frequency ranges of the bats we were picking up on the bat detectors would have been more helpful -- but you can't have everything. We did an emergence watch and saw quite a few brown long-eared bats (Plecotus auritus) leaving their roosts in one of the older buildings at Delamere. They were really loud at the 43 kHz range on the bat detectors, which is no surprise as their call range is 27-56 kHz. However, it's really worth noting that you'll see these critters before you hear them usually as the detectors only work on their quiet calls up to a distance of 6m, hence their other name, whispering bats. A good daylight indicator of these chaps being around is moth wings under the roost (most favoured moth being the Yellow Underwing) and of course, bat droppings on the wall.
As soon as they left the roost, they immediately headed for the closest tree to feed. They are gleaning feeders, meaning that they eat the insects that alight on leaves and tree bark. Unfortunately, as it was a bit dark and the bats were a bit far away (who'd've thought, eh?) I wasn't able to get any pictures of any bats that evening, however, here's a picture from wikimedia commons of what a brown long-eared bat looks like:
They look far more charismatic as a species when they're moving and not stunned. Bad photos even happen to bats, apparently!
The next bats we fleetingly saw and certainly heard were the pipistrelles. There are two types of pipistrelle -- the common pipistrelle (Pipistrellus pipistrellus) and the soprano pipestrelle (Pipistrellus pygmaeus). The main identifying difference if you're spotting using a detector is that the common pips have a call with most energy at 45kHz, whereas the soprano pips have a higher echolocation call at 55kHz. We also heard a few social calls down in the 20kHz range. Social calls are the bat world's version of a male bat calling out "hey, ladies!", especially when you bear in mind that bats have harems.
The calls of these bats are interesting to listen to as you can actually hear them hunting. When they dive to catch an insect, it sounds like someone has just blown a raspberry. When it stops, chances are that the bat is having dinner.
I'm fairly certain I also heard a Natterer (Myotis nattereri), though as the pips were around at the time and were being pretty loud, it was hard to tell. However, it wasn't the same sound and the frequency went as high as 70kHz before suddenly stopping rather than fading out. The lovely folks from the local bat group seemed to think it was a good possibility though.
Either way, they were amazing to watch and to hear. It's just a shame their body-clocks are so antisocial!
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