Forum Topic

Bats by the Rjver

On Sunday evening we went for a Bat walk along the Thames path from the Putney boathouses to the Wetlands centre. We were a little concerned last year that the bat population had diminished after the rather savage trimming of the trees along the "towpath". However, now they've grown back there seems to be a massive resurgence in the number of bats, which is a good sign.  Two short videos of pipestrelle bats by the Wetlands, Barnes; ignore planes joggers, etc 😶 (Bat box set to pick up 50 kHz echo location frequency.)https://flic.kr/s/aHsmFmVigs

Michael Ixer ● 2669d18 Comments

That is very good news.

Ivonne Holliday ● 2669d

Fantastic videos Michael! 👏🏻 They are such interesting creatures and you have even managed to capture that odd clicking sound they make.🦇Thankyou for sharing. xx

Sue Hammond ● 2669d

Thanks, Sue. Yes, they are fascinating and it's good to see them thriving. The clicks are from the bat detector: it takes the ultrasonic bursts of sound the bats use to navigate and translates them into the clicks that humans can hear.  We set it to 50 kHz which on our detector will pick up common (45 kHz) and soprano (55 kHz) pipistrelles. (For reference, CDs have a top frequency 20kHz.) 

Michael Ixer ● 2669d

Oh I thought the sounds were actually coming from the bats themselves but you have explained it very well. Is this the way bats also communicate with each other and do the different species make slightly different sounds in flight?

Sue Hammond ● 2669d

Each bat species uses a different frequency for echolocation, which they use for navigation in the dark to avoid obstacles and locate insects for food. This is one species/echolocation frequency table:  http://www.staffordshirebats.btck.co.uk/Information/FrequenciesI believe they use other high frequencies for communicating with each other: warning of danger, identifying each other, asserting territory, mating calls, etc but I must admit I don't know too much about that. I believe the saying "blind as a bat" is untrue, in light they apparently have quite good sight but obviously at night, when they're usually looking for insects to eat, there's little or no light to see with.

Michael Ixer ● 2669d

Thanks Michael that is very interesting. Do you go on the bat walks in Wandsworth Park?

Sue Hammond ● 2669d

We go to Wandsworth Park for walks, normally early in the day but one time recently was we were leaving the Park at dusk after going for a walk to Point Pleasant we spotted a bat passing through the trees. Wimbledon Common also has bats, including Daubenton bats on (I think) Queensmere which skim just above the water for insects. They're also in the Wetlands but you can only get in on an organised tour to see those.

Michael Ixer ● 2669d

The reason I asked is because the FoWP have organised bat walks, the last one was in May I think. I assume there are quite a number of bats in WP or the walks would be pointless lol.

Sue Hammond ● 2669d

Think I've had bats in my garden as something dive bombed me and very high tree's in next door garden. This was when getting dark.

Barbara Stevens ● 2669d

Lucky you, I'm jealous Barbara. Might have been a stag beetle though.

Sue Hammond ● 2669d

Sue, I am so happy I found a stag beetle in the garden yesterday.

Martine Guy ● 2669d

OMG! 🙀

Sue Hammond ● 2669d

Yes I did think of you.

Martine Guy ● 2669d

Sue funny you said that, there used to be stag beetles in a lilac tree, but that was cut down and they disappeared.

Barbara Stevens ● 2669d

Word association?😉Stag Beetle>Sue

Sue Hammond ● 2669d

Barbara, perhaps they've set up home in another tree nearby? I won't say lucky you this time lol.

Sue Hammond ● 2669d

Sue, don’t you remember we had a stag beetle thread on the Forum and I think you said you weren’t keen on them?

Martine Guy ● 2669d

It was a while ago, I was worried they would hurt my little yorky or the cat. Haven't seen any for a few years now.x

Barbara Stevens ● 2669d