Bat Echolocation Frequencies: A Species Guide for Surveyors

Different UK bat species echolocate at different peak frequencies, ranging from around 18kHz for noctules up to around 110kHz for lesser horseshoe bats. Almost all of that range sits above human hearing, which tops out at roughly 20kHz, so a bat detector isn't optional kit for acoustic identification; it's the only way most calls become audible at all.

Frequency alone doesn't confirm a species on its own. Call shape, rhythm, repetition rate, and habitat all matter too, and the same bat can shift its peak frequency noticeably between open commuting flight and cluttered woodland. But knowing the typical range for each species is still the starting point for tuning a detector and for making sense of what it's telling you. If you want the fuller picture of how bat identification works, including why frequency alone rarely settles it, our piece on bat identification covers the science behind it.

Peak frequencies by species

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  Common pipistrelle (Pipistrellus pipistrellus): around 45kHz
• Soprano pipistrelle (Pipistrellus pygmaeus): around 55kHz
• Nathusius' pipistrelle (Pipistrellus nathusii): typically below 40kHz, with a slower repetition rate than the other two pipistrelles
• Noctule (Nyctalus noctula): 18 to 27kHz, often alternating between higher and lower calls to produce a distinctive "chip-chop" sound
• Leisler's bat (Nyctalus leisleri): around 25kHz, similar in style to the noctule but with less predictable alternation
• Serotine (Eptesicus serotinus): around 27 to 32kHz
• Myotis species (Daubenton's, Natterer's, whiskered, Brandt's): calls sit broadly between 35 and 50kHz, heard as short clicks rather than smacks or warbles, with Natterer's typically faster and quieter than the others
• Brown long-eared bat (Plecotus auritus): similar frequency range to the Myotis group, but extremely quiet, sometimes described as a "whispering bat" since it's barely audible even with a detector close by
• Barbastelle (Barbastella barbastellus): alternates between around 32kHz and 45kHz
• Grey long-eared bat (Plecotus austriacus): the UK's rarest bat species, with only a handful of known maternity roosts. Frequency and call style are very close to its brown long-eared cousin, so confirming it typically needs more than acoustic data alone
• Greater horseshoe bat (Rhinolophus ferrumequinum): around 82kHz, a continuous, loud, warbling call
• Lesser horseshoe bat (Rhinolophus hipposideros): around 110kHz, similar in style to the greater horseshoe but pitched higher

Why this matters alongside night vision survey work

Acoustic detectors and night vision aids are complementary rather than interchangeable. A detector picks up echolocation calls that confirm species presence and can help identify what's emerging, while night vision or thermal equipment lets a surveyor actually see the emergence itself, count individuals, and pin down the exact access point a bat is using. Neither on its own gives the full picture: a detector without a visual reference can't always tell you which of several nearby features a bat came from, and visual observation alone can't reliably confirm species for many bats, particularly quiet ones like the brown long-eared bat.

Detectors themselves come in a few different types. Heterodyne detectors shift a chosen frequency band down into human hearing range in real time, useful for quick fieldwork but limited to one frequency at a time. Frequency division and full spectrum detectors capture the whole call and either divide or slow it down for playback and later analysis, which is why full spectrum recordings are generally preferred where accurate species identification matters, since nothing gets filtered out in the field.

This is part of why the BCT technical guide on night vision aids for bat surveys treats time-matched acoustic recordings as standard practice alongside NVA footage, rather than as a separate exercise. If you're planning survey work and want the fuller detail on timing and methodology, our piece on bat survey season covers how these visits are scheduled and spaced across the season.

What else helps confirm a species

Frequency is the starting point, not the whole answer. A few other things ecologists and experienced bat enthusiasts factor in:

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  Call rhythm and repetition rate, since some species call in a steady, evenly spaced pattern while others are more erratic
• Call duration and pulse interval, the length of each individual call and the gap between them, which vary by species and by whether a bat is in open flight or working close to clutter
• Habitat, since certain species are strongly associated with woodland edges, water, or open farmland
• Timing of emergence, since species vary in how soon after sunset they typically appear
• Roost type and location, which can rule some species in or out entirely depending on the structure involved

This is also why frequency ranges overlap between some species. A bat calling around 45kHz could plausibly be a common pipistrelle, but without other context, that frequency alone isn't a confirmed identification. Reference call libraries and identification keys, the kind used for species identification work feeding into the National Bat Monitoring Programme, cross-check exactly these features together rather than relying on frequency in isolation.

A few genuinely strange things bats do with sound

• Feeding buzzes: as a bat closes in on an insect, its call rate speeds up dramatically into a rapid buzz, sometimes over 100 calls a second, giving it a near-constant stream of positional updates in the final moments before capture. It's one of the most recognisable sounds on a detector once you know what you're listening for.
• Doppler shift compensation: horseshoe bats fly and call at the same time, which means their own movement shifts the pitch of the echo they hear back, the same Doppler effect that changes a siren's pitch as it passes you. Horseshoe bats actually adjust their outgoing call frequency in real time to compensate, so the echo always lands back at the frequency their ears are tuned to.
• Social calls: not every sound a bat makes is for navigation. Bats also produce lower-frequency social calls for communication between individuals, at roosts or in flight, which sound quite different from an echolocation call on a detector and are usually left out of frequency charts like the one above entirely.

FAQs

What frequency do bats echolocate at? UK bat species echolocate at peak frequencies ranging from around 18kHz (noctule) to around 110kHz (lesser horseshoe bat), almost all of it above the upper limit of human hearing.

Can humans hear bat echolocation calls? Generally no. Most UK bat calls sit above roughly 20kHz, the upper edge of human hearing, which is why bat detectors are needed to convert them into an audible range.

How can you tell bat species apart using a bat detector? Peak frequency is the starting point, but call shape, rhythm, repetition rate, call duration, and the interval between pulses all help confirm species, since several species have overlapping frequency ranges and the same bat can shift frequency between open and cluttered flight.

Do you need both a bat detector and night vision equipment for a survey? They serve different purposes and work best together. A detector helps confirm species from echolocation calls, while night vision or thermal equipment lets a surveyor see the emergence itself and confirm exact access points, something acoustic data alone can't always do.

What's the difference between heterodyne, frequency division, and full spectrum bat detectors? Heterodyne detectors shift one chosen frequency band into human hearing range in real time. Frequency division and full spectrum detectors capture the entire call for playback or software analysis afterwards, generally giving more reliable species identification since nothing is filtered out during recording.

*Cover photo credit: the_biodiversity_ecologist