Hi Anna, I'm unsure what you mean by activity. If you mean activity patterns, then you'll need a temporal record of when bats are calling. If you mean as a measure of abundance to relate to moth/prey abundance, then you'll need to to validate that the number of calls relates to abundance (and I'd account for detectabilty too). I think Brad Law in Australia has used number of calls as a measure of abundance and validated the method, and he uses an automated ANABAT recorder and call ID.

Hi Anna and Matt. I agree with Matt when he says the activity patterns and also the measure of abundance to relate to moth / prey abundance. I'm starting to work with bioacoustics, with the company Wildlifeacustics. The equipament Echo Meter EM3+ proved to be very efficient to point abundance of records of bats activities. Although I am starting my research with this equipment, I can guarantee you that it is robust enough to enable information and data on bat activities, and in addition you also have a lot of information about echolocation and ultrasound emissions. 

Thanks both for your answers. The Wildlife Acoustics iphone microphone plug in looks like a really good tool for citizen science!

If I were to use number of calls as a measure of abundance, would I need to have a full spectrum device or could that be done with zero-cross analysis? Fernando, I see that the EM3+ has both capabilities, which mode are you recording with?

Thanks again!

I am also working with bioacoustics. Recording insectivorous bats in Mexico in the INECOL AC. I think in a cost benefit and also depending on how much budget you have, the Ultramic is pretty good. I have also had the opportunity to use the M2 Petterson 5000 and until now also choose the M2 or M3 of Wildlife acustics. For the analysis of the recordings, now the most appropriate and best to do is to treat them by automatic means, but this is only possible with an average or above budget. I still have much to learn, I hope I serve something centrate on information and experts and q methods have done. Greets :)

I use Pettersson D-240X paired to an MP3 recorder and let it record all night long. Then I use Sonobat software to help with species ID. This is a full spectrum set-up. There are pros and cons for using full spectrum and zero cross for acoustic purposes. Do a search and you will see a few papers discussing the merits of both techniques. The bottom line is that one is no better than the other. A solid design would be to use acoustics and netting to qauntify bats, or to use a combination of full spectrum and zero cross. As was stated earlier, you should deploy a few stations (or volunteers) along a stretch of the study area. The size of your study area will determine how many sample stations you will need. I recommend you survey during spring, summer, and autumn.

I used number of bat passes per hour to quantify activity. Then I pooled the calls from a stretch of river during a 1 month time period. Of course a bat pass could be navigation calls, social calls, feeding buzzes, prey search calls, etc. Whatever you use, be sure to explicitly state your metric in your methods. Also realize activity at a sample site can vary between nights, seasons, and even within a night. So, you may want to resample the same site, or establish a series of stations during different nights.

Hi Anya. As I said, I'm starting studies with these devices. I think that the explanations of full spectrum and zero cross were well presented by Charles. I am a beginner in this area and have much to learn. I returned last night from my trip to the Lauraceas State Park, where I installed the Song Meter SMBAT+ to record bat activity and diversity. When we're there, we used the active device, the Echo Meter EM3+ recording in real time the species that are active and foraging activities.  We recorded several different species, including Myotis. We will have much work to analyze these data. Greetings. Fernando

Fernando seems to have very good suggestions. I'm using a large number of automatic recorders (34) to study a 1700ha forest for bat activity in consequent years from April to early October. The amount of data is huge, so it is worthwhile looking into automatic all identifiers. I'm using the Sonochiro-software which seems to be pretty intuitive to use.

Thomas, the area where I and my team are conducting our research on bat survey and bat ecology with the Wildlifeacustics devices and mist nets has 32,000 hectares of Atlantic Rainforest in Brazil. This is a very large area. We need to use several methods to raise the bat diversity and ecology, including search in shelters, where we can find and catch species not recorded in mist nets. The Song Meter SMBAT+ and the Echo Meter EM3+ can help to record species like these. Greetings. Fernando

In the Netherlands we've used Batloggres of Elekon and let people place those in their backyard and then have them pass the Batlogger on (Hopping Detectors). It is a easy to use real-time recorder with free (!) identification software of good quality (Batexplorer/Batscope). It can store up to 128Gig of recording on a sd card. The identification software is easy to use, also for less experienced batworkers. And you can quickly identify 95% of the recordings as Pip pip so you can concentrate on the remainder for diversity (rare species) and use the 95% for activity...

Compared to EM3 the microfones on the Batloggers are senitive and picked up more calls in general and more  calls of the low frequency group. That migth ofcourse change in the future.

As a relatieve measure of activity (and certainly not # animals) we used #passages (a passage is one recording, one recording can hold several calls). 

We started to use the same divice for several other citizen science projects. People find it very easy to use and the recordings are good and results are surprising (rare species picked up in locations we didnt expect them).

Well worth a try in my opinion!

Hope this helps.

These answers have been so helpful. I'm surprised to see that no one is mentioning the Titley Anabat. I suppose that's because it does not have full spectrum capabilities, and is therefore not sufficient with the goal of measuring activity. Just out of curiosity, does any one use an anabat for projects that only need zero-cross data? Is it becoming obsolete? I have been using one only because it's the only device I've had

Just knowing that auto-identification software exists and is being used by professionals in the field is very encouraging. I've been trying to self-train on reading sonograms for common species in my area and it's proved quite challenging! Marcel, it's great to know your citizen scientists have been successful  using Elekon.

Thank you all!

Anya,

You can still acheive the goal of bat activity with zero crossing. A bat pass, whether it be a single call pulse or a train of pulses, can be detected and qauntified using zero cross. You can use this data to get at the activity level during the sampling period at your site. Because bats can move long distances and will visit many sites, it is best to sample many sites to get an overall picture of activity. You can even count the number of feeding buzzes and targeting pulses to get an idea of what sites are used for feeding-all with zero cross. Many things must come together to successfully record a call: microphone orientation, bat position relative to the microphone, air humidity, background noise dB (calling insects and frogs), where the bat's head is oriented during pulse generation, etc. So just because you fail to record a certain species or get low activity at an otherwise "juicy" site does not mean bats were not there or will not be there another night. Such is the fun of chasing bats.

You can also ID species with zero cross-check around because ANABAT has species ID software (ANALOOK). One thing acoustics only limits your understanding to is that a bat from species A made X passes at the site during the sampling period. Mist netting will give you the sex, reproductive condition, relative age, morphometrics, and an indication of how many bats were present. Acoustics can't do that. Good luck and don't give up.

Cheers,

Charles

Hi Anya,

As you can see you've stumbled into a complex topic. I helped develop Sonobat automated identification software for my master's degree, so I am partial to full-spectrum acoustic analysis. However, Anabats are still commonly used, despite the fact that they discard a wealth of information in the transformation from full audio to zero-crossing. That said, in many cases zero-crossing can give the ability to identify species, and as others have mentioned there are automated tools for analyzing Anabat data, as well as full-spectrum data. In the U.S., Sonobat and Kaleidescope (through Wildlife Acoustics) are commonly used for automated species identification.

I would add one precaution, which is that no automated identification tool for bats is perfect. Especially in areas where there is high bat diversity there will always be some calls that cannot be identified to species, and some calls that are mis-identified. That's because bats make a huge variety of calls and no automated classifier can ever cover the entire range of calls that bats make. For you and others who are interested, there are classes offered by Bat Conservation International and Bat Conservation and Management to teach people how to do all this stuff.

Good Luck!