UK Bats

Question 1

what is the scientific name for a Noctule bat?

Answer 1

(Nyctalus noctula)

Question 2

what is the scientific name for a Soprano pipistrelle?

Answer 2

(Pipistrellus pygmaeus)

Question 3

what is the scientific name for a Common pipistrelle?

Answer 3

(Pipistrellus pipistrellus)

Question 4

what is the scientific name for the serotine bat?

Answer 4

(Eptesicus serotinus)

Question 5

what type of detector is a heterodyne detector?

Answer 5

tuneable with a dial. The bat calls are picked up by an ultrasonic microphone and mixed with the output of a high frequency oscillator in the bat detector. This produces sounds that are the sum and difference of the two frequencies. Thus if the bat detector is set to 50kHz and an incoming bat call is at 49kHz then the difference is 1kHz which we can hear. The sum signal (99kHz) is ignored for obvious reasons! Clearly if the bat call is at 50kHz then we hear nothing, so the output of the bat detector is not an accurate reproduction of the original bat call. However, bats never emit a precisely steady sound, so this is not any problem in practice. By adjusting the tuning frequency of the bat detector we can “listen” to different portions of the bat call and with practice can distinguish the calls of a number of bat species or families.

Question 6

what does a bat use to navigate its surroundings?

Answer 6

echolocation They make high frequency sounds and listen for the echoes that bounce back to give them information about the world around them. The sounds that bats make are usually high above our hearing. Human hearing generally can take in sounds up to about 20kHz. Most bat calls are between 20 and over 100kHz, far above our range. The detector brings the frequencies down to around 0.1 – 10kHz so that we can hear them.

Question 7

how far away can a brown long eared bat be heard?

Answer 7

around 10 metres away, they have quiet calls

Question 8

how far away can noctules be heard?

Answer 8

50-100 metres, they have very loud calls

Question 9

what does a soprano pippistrelle sound like at 48khz?

Answer 9

short popping sounds like bubblewrap, this popping sound occurs more around 48khz and the clipping sounds occur at 45khz, This is characteristic of the pipistrelles.

Question 10

what is a noctule bats peak frequency?

Answer 10

Noctule bat 21kHz or below

Question 11

what is the peak frequency for common pipistrelles?

Answer 11

Common pipistrelle 44- 48kHz

Question 12

what is the peak frequency for soprano pipistrelles?

Answer 12

Soprano pipistrelle 52 - 63kHz

Question 13

what does a soprano pippistrelle sound like at 45khz?

Answer 13

very short clipping twittering sounds, high pitched and different to the noctules twittering birdlike sounds

a popping sound occurs more around 48khz and the clipping sounds occur at 45khz, This is characteristic of the pipistrelles.

Question 14

what is peak frequency?

which detector needs this technique?

how do you do it?

Answer 14

this technique is for heterodyne detectors

when a bat comes by, you wobble the dial to a slightly higher frequency and then to a slightly lower frequency. In one direction the tone or pitch of the sound will generally become noticeably lower and in the other direction it will become higher.

Continue to turn the dial in the direction of the DEEPENING note. The sound should also start to get louder.

When you get to the deepest note you can read the dial and that should give you the peak frequency the bat is using. It is usually just beyond the loudest frequency.

Many bat species use typical peak frequencies and finding this can help us to identify them

Question 15

what do echolocating noctules sound like on a frequency division bat detector?

Answer 15

frequency division:

short and slow, thudding sounds with higher pitched ends

The noctule bat typically uses a two-part call often referred to as a ‘chip chop’ sound. Each pulse is fairly long compared to other bats and this gives it a very rich flavour.

These bats are big and fly fast but the repetition rate of the calls is slow, on average about 4-5 pulses per second, but sometimes even less as they fly high above the trees.

Identifying Typical Noctule Calls:

• Call often has two parts and sounds like ‘chip-chop’ (but not always alternating).
• Repetition rate slow at 4/second (sometimes down to 2/second)
• Rhythm - regular punctuated with erratic bursts
• Tonal quality - deep, rich ‘chop’ sound & slightly higher ‘chip’
• Pitch/peak frequency – deepest at 21kHz or below

Question 16

what type of bat is this?

Answer 16

Noctule bat

Nyctalus noctula

Question 17

what is the peak frequency of serotine bats?

Answer 17

Serotine bat 25 - 32kHz

Question 18

what is the peak frequency of lesser horseshoe bats?

Answer 18

Lesser horseshoe bats 110kHz

Question 19

what is the peak frequency of greater horseshoe bats?

Answer 19

Greater horseshoe bats 81kHz

Question 20

what bats fall under The Myotis bats?

Answer 20

whiskered, Brandt’s, Daubenton’s, Bechstein’s and Natterer’s bats

Question 21

what are the frequencys you hear myotis bats?

what do they sound like?

Answer 21

With the Myotis family of bats the pitch of the sound does not significantly change wherever you tune. The calls sound like dry fast clicks/hammer taps wherever the dial is positioned.

Myotis bats use calls that sweep through many frequencies from around 70+ kHz down to 30kHz.

Wherever the dial is tuned however the fast dry clicks sound pretty much constant in pitch and tone, and the sound remains essentially the same

Question 22

what is reptition rate when listening to bat calls?

Answer 22

The repetition rate refers to how fast each bat call follows the previous one in a series. In general it is related to the size of the bat (big bats tend to be slower) and the habitat (out in the open bats make slower calls than when flying between obstacles among trees, hedgerows etc).

Question 23

what is rythem when listening to bat calls?

Answer 23

Rhythms relate to how the bat is flying. Bats flying in straight lines have regular rhythms and bats that tend to make lots of twists and turns tend to have erratic rhythms.

Question 24

what is tonal quality when listening to bat calls?

Answer 24

The tonal quality or flavour of the call varies between species. Some use deep, rich sounds and others flatter, ‘tinny’ calls. It relates to the duration of the call and long calls sound richer than short ones. The pitch or note helps us to find the peak frequency or where the bat is putting more energy into the call.

Question 25

when is the best temp to survey bats?

Answer 25

If it is too cold this will put bats off as insects will not be abundant. Try and choose a warm evening as bats rarely fly in conditions below 7°C. Bats will fly in light drizzle but ideally it should be dry and forecast to stay dry for the evening

Question 26

what should you do to start off your survey?

Answer 26

start around 20 minutes after sunset

Just prior to starting the survey make the following pre-survey observations and record them on your recording sheet:

1. Start time
2. Temperature (use a thermometer or check next day’s newspaper/web reports).
3. Weather conditions
   Weather conditions that may affect bats are recorded including cloud cover, wind speed and rain. Estimate the conditions based on the following options:

Cloud:
• Clear (0 -1/3 of the sky covered with cloud)
• Patchy (1/3 – 2/3)
• Full (3/3)

Wind:
• Calm
• Light
• Breezy

Rain:
• Dry
• Showers
• Drizzle

If wind is more than breezy, or rain is more than a shower or drizzle then you should not do the survey.

Question 27

what procedure do you follow on walk 1 after starting off your survey?

Answer 27

Once you are ready and have recorded the conditions, the survey starts with Walk 1.

Remember to hold your detector up at a 45 degree angle and begin walk 1 with your detector tuned to 25 kHz as illustrated in the video clip.

Walk at a steady pace counting any noctule or serotine bat passes only. When you hear a bat, you can take a few moments to stop and identify the species. Immediately after identification continue walking and counting the passes. If you are surveying in pairs one of you could count while the other tries to identify.

If you think a bat pass was by a noctule or a serotine but you are unsure which, note it down as “unsure”.

When you reach the first spot, stop - this is the end of “Walk 1”. Record the total number of passes on your survey form under “Walk 1”.

Question 28

what routes do bats like to follow when emerging?

Answer 28

When bats emerge from the day roost they often follow certain linear features like hedges or tree lines, keeping close to cover to fly to their feeding sites.

Question 29

what does a serotine bat sound like?

Answer 29

You can hear that the rhythm is very irregular, sometimes faster and sometimes slower and it has quite a musical effect.

Identifying Typical Serotine Calls:

• Never a two part call, single call sounds like ‘tock’
• Repetition rate - slightly faster than noctule 5-6/sec
• Rhythm – erratic and sometimes ‘funky’
• Tonal quality – not as rich as the noctule
• Pitch/peak frequency – deepest at 25-32kHz

Question 30

how do you tell the difference between a serotine and a noctule bat call?

Answer 30

the noctule call is two part and regular, crisper popping sounds

the serotine is three part and irregular, speeds up and slows down. serotines call is slightly duller and has more of a tap sound to it

Question 31

what bat is this?

Answer 31

serotine bat

thin tragus no mushroom shape

Question 32

what bat is this?

Answer 32

serotine bat

Question 33

what bat is this?

Answer 33

noctule bat

Question 34

what bat is this?

Answer 34

soprano pipistrelle

Question 35

what bat is this?

Answer 35

soprano pipistrelle

Soprano pipistrelles are small, usually a uniform brown colour. The main difference is the face. The muzzle is upwards pointed and the face often light brown or pinky. In contrast the common pipistrelle has a darker face, hence the name bandit. The muzzle has better developed glands that can appear to be quite bulbous.

Question 36

what bat is this?

Answer 36

common pipistrelle

common pipistrelles have much darker faces,

Dorsal fur is dark to chestnut brown. Ventral fur is paler.
Ears are short and triangular with a rounded tip.
The tragus is up to four times as long as it is broad.
The wing membranes are opaque.
The calcar is up to 1/3 of the length of the tail membrane and a post-calcarial lobe is present.
The penis is slightly bulbous.
Average weight (as given by Greenaway & Hutson, 1990) 4-8 g.

Question 37

how do you tell the difference between a noctule and serotine bat?

(looks not bat call)

Answer 37

Noctule 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 steep dives to catch prey in the air. The wings beat deeply and the flight is very fast.

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

Serotine bats often look heavier and darker. 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.

Be aware that the serotine’s distribution is limited in the UK. It mainly occurs in the south of England. However records have been received from as far north as Derbyshire and as far West as Cardiff.

Question 38

how do you distinguish between a serotine and noctule bat using a detector in a field survey if youre unsure?

Answer 38

1. Pause. Walking creates a lot of noise at 25kHz so it is best to stop.
2. Listen to whether you can hear a two part call or a single type of call.
3. Focus on the repetition rate and the rhythm and see if it is slow and regular or funky.
4. If it is two part call tune slowly down towards 20kHz and see if the sound gets deeper.
5. If sound does get deeper find the peak (deepest) – if it is below 21kHz it is likely to be a noctule
6. If the sound gets higher as you tune to 20 go back up to 25 or above and try to find the peak frequency. For a serotine it will be 25 or above.
7. Look for visual clues

Question 39

Answer 39

brandts bat

bulbous penis, light to dark ear colour,

Question 40

what TYPE of sonogram is this? (not what species)

Answer 40

social call

What it looks like

The spectrogram may show “V” shaped and tick shaped calls.

Social call example Play

What it sounds like

These sound like bat calls but with trills, and they’re much closer together than normal bat calls. They may also have a different pitch than normal calls.

Question 41

what TYPE of sonogram is this? (not what species)

Answer 41

searching

What it looks like

Spectrograms show a well defined pulse of sound, usually between 13KHz and 120KHz. There are usually a number of regularly spaced pulses making up a sequence. The shape of the pulse can range from:

Vertical hockey-stick shaped Play

Flatter, more horizontal hockey-stick shape

Thin vertical line

Flat table or plateau shape

What it sounds like

Searching calls can sound like a chirp, a squeak or an airy whistle.

Question 42

what TYPE of sonogram is this? (not what species)

Answer 42

feeding

What it looks like

On the spectrogram you can see pulses getting closer and closer together, with the lines getting shorter and shorter.

Buzz-shaped Play

What it sounds like

These sound like normal bat calls but the calls get closer and closer together until they terminate abruptly.

Question 43

what TYPE of sonogram is this? (not what species)

Answer 43

insect

What it looks like

The spectrogram can have fast evenly spaced pulses near the bottom, much closer together than bat calls, or it might look like messy background noise in which you can hear distinct sounds.

Distinct pulse Play

Like a car alarm

Messy spectrogram

What it sounds like

These sound like a rattling, a buzzing, or like a car alarm

Question 44

what TYPE of sonogram is this? (not what species)

Answer 44

What it looks like

The spectrogram appears random with no regular patterns to the noise, and may have either vertical or horizontal lines.

Car background noise Play

Click

Horizontal spectrogram

Vertical spectrogram

What it sounds like

These can sound like a click, a crackle or static noise, or something metallic like the sound of a workshop. Some may sound like listening out the window of a moving car