Identifying Bats

Does anyone have any recommendations for identifying bats? There’s been several that have been flying around my neighborhood (Los Angeles) every evening and I’d like to know whether there’s an app for recording their calls or a way to identify them visually. I did learn some bat taxonomy and ID in college but that was mostly with prepared specimens.

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I am no where near educated enough to sufficiently answer your question however, I can help a little. There is a machine which is reasonably hard to get your hands which records bat sounds. It can be bought online or given to you by a local scientist who specializes in bats. However if you can’t get the machine try this. If you do have the ability to actually find where the bats roost try your best to get pictures of the bats face. Try your best not to disturb the bats but, you NEED the bats face for a confident ID to species. If your are to scared or don’t want to risk scaring the bats just get pictures of the bats body and coloration. Though you most likely won’t be able to get the observation to species it will get far enough. However, the first option is the best though.

  • Jonny
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The device you mentioned is generally referred to as a bat detector (clever, right?), and works by making recordings with a specialized high-frequency microphone. One of the more readily available ones comes from Wildlife Acoustics (here: https://www.wildlifeacoustics.com/products/echo-meter-touch-2-ios, they also have an android version). The software does attempt to make an ID based on the call characteristics; however, I will caution that the automatic IDs are extremely unreliable. It’s not necessarily a fault with the software, it’s mostly that the calls of bats are highly variable and bats hunting similar prey in similar environments often make similar calls.

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A bat detector is the best way to get an approximate ID without disturbing them. Trying to get into a roost to identify them visually should not be done if you’re not experienced as you will likely disturb them and it may even be illegal to do so (I don’t know the specific laws in California but in many places it is illegal to disturb bat roosts without a license).

As @neotomastolemykeys mentioned, the Echo Meter Touch is a detector that plugs into a phone or tablet and allows you to listen and see the calls on a spectrogram. These detectors are very good in my experience as they are full-spectrum (meaning they pick up various frequencies at the same time), allow you to listen in real time AND record, and they give possible IDs. And while they’re not completely reliable, the ID is often accurate to genus level.

If you can’t or don’t want to spend that much money on a detector, I would recommend looking into a “heterodyne” detector. These tend to be cheaper, and while they don’t have all the features of the EM Touch, they’re still good and with some research online listening to recorded bat calls, you can learn to identify some species with one. The main downside is that heterodyne detectors need to be tuned to a particular frequency, so you can only pick up calls that are around that frequency, meaning you can miss other calls. The heterodyne I have is a Magenta 4, which is quite affordable for a bat detector, however I think this might be a UK brand so I don’t know how available it is in the US.

You could also look into whether there are any local bat-watching groups you could go to, as these would probably give you a chance to try out detectors before buying (though obviously, if there are any groups, they may not be running right now).

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@corvidaeus I probably shouldn’t sound quite so harsh on the auto-ID from the handheld detectors, but I’ve had some real struggles in areas with high bat diversity. I do a lot of bat call ID professionally, and it can be really tricky in parts of the U.S. where we regularly get 11-15 species, all of which are operating in the 20-50kHz range. I think the handhelds are a fantastic tool for learning and discovery, and you can make recordings of bats with definitive calls for proper identification, but I feel somewhat obligated to advertise ahead of time for folks that the auto-IDs aren’t sufficient on their own for species ID in most cases.

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Quite simply, bats can be tough. Acoustic data (i.e., a sonagram of the call) from a bat detector isn’t always definitive. For many Myotis species, a photo isn’t always diagnostic unless you get close-up photos of certain features such as the calcar and take measurements of ear, forearm, body length, etc. Even bat specialists are challenged by some individuals that they have in hand. Unfortunate, but that’s the reality. But, if you live in an area where the bat diversity is rather low, you might have an easier time narrowing down what you have.

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I totally understand, I also do bat surveying professionally and there is a lot of overlap in the calls, and you’re right that they’re usually not sufficient for species-level ID. Most of the species I encounter here in the UK can at least be narrowed down to genus level using the detector, and the auto-ID has generally been correct on that (I don’t think I’ve ever had it suggest Myotis when encountering a pipistrelle, for example). But yes, I imagine it would be more challenging in areas of higher diversity - many of our bats are quite rare and we don’t tend to get more than 3 or 4 species at one time.

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