1. WHAT AND WHY?
Passive sound-recording (PSR) is viewed upon by some as “cheating”, in that it is achieved without the operator present. NocMig is one of the more famed members of the PSR family, but can also be carried out during the day. Another example of PSR can be achieved with the use of “drop-rigs”. Drop-rigs are typically water-proofed, compact recording devices which, as the name suggests, dropped off at a location of choice, usually, but not always, with a particular target in mind. The device is set or programmed to record of its own accord, without the need for a physical presence. Whatever the view on the authenticity of the technique, there is no doubt that it is very effective and can produce show-stopping results. Read on for a list of some of the numerous positives associate with PSR:
- Animals (birds, mammals or otherwise) can be sound-recorded in more natural circumstances, as they are not influenced by the operator’s presence.
- It is possible to obtain extremely close recordings of your target, with some careful planning.
- Because drop-rigs can be placed right at the point where an animal is expected to vocalise, a high-quality audio can be obtained with even the cheapest of equipment.
- Shy or nocturnal species can readily be recorded using this technique.
- One can amass a very large volume of data (up to several months or more) without having to put in the man-hours, in the field (it will still require man-hours to process and edit).
- It means you can never be too busy to record!
- It’s exciting! When it comes to retrieving the device, the mystery of what may or may not have been captured can be thrilling, although it can be equally nerve-wracking, wondering whether or not your device has been stolen or damaged.
2. WHAT DO I NEED?
Passive-recording can be achieved with all manner of devices. Because the unit can be placed right at the point where you expect your target to vocalise, you can obtain extremely nice results with even the cheapest of equipment. To keep things simple, and to demonstrate this point, we will talk you through the three pieces of kit we currently use to passively record, with a very impressive bonus setup used by Cork-based birder Thomas Wallenda.
Let’s start with the deservedly popular, and amazingly versatile Audiomoth. Despite being the size of a matchbox, this little device packs a powerful punch. It takes three AA batteries and can last weeks in the field. It is highly programmable and gives you to power to tell it when and for how long to record. It is easily water-proofed, using a ziplock bag, or a small junction-box with a small opening, sealed with light plastic. To demonstrate what this gem is capable of, let’s take a look at some of our favourite passively-recorded tracks using the device.
If you’re feeling a little bit braver, you can also leave a handheld recorder or even a parabola out in the field. Why risk it? Well, the sound quality, or in the case of the parabola, the quality and range will be greatly increased. Of course it is only advisable to do this if you feel confident enough that your expensive equipment won’t be stolen or damaged. Let us talk you through some of our past scenarios with samples.
First up is the handheld recorder. We love our Olympus LS-12 and because of this, wouldn’t leave it anywhere too risky. It wasn’t the most expensive piece of kit but they cost quite a bit more than an audiomoth and are discontinued. As we are often in the field surveying, this little device is often sealed in a ziploc bag and left out to capture some of the natural sounds of the environs. It’s usually close enough to keep an eye on and because we aren’t targeting flying birds, it works just fine as is. Of course, it could be used to target a specific bird or mammal too.
We often use our parabola to passively record, with amazing results. Setting up a parabola to point towards a bird-feeder or area which hosts a hive of bird activity is a great way to cheat yourself some nice bird audio. You can be working from home, whilst recording at the same time, with your equipment in a safe place. Don’t have a garden? Don’t worry – just find an area out in the countryside that has a lot of bird activity, setup your device to record, and retreat to a safe distance. Whilst surveying in nice conditions we often run our parabola alongside. But of course, it’s not essential to do this with a parabola. Just work with what you have. As we’ve said before: good quality recordings are possible with even the cheapest of devices.
Now for something a little bit different: Cork-based birder Thomas Wallenda uses a highly inventive Raspberry-Pi setup to passively record in his garden with great success. The sound quality is very nice and to our surprise everything was very cheap. Thomas tells us that he has had this setup in a bush for over a year now, with no rain-based or any other form of damage incurred.
Here are some more technical details, kindly provided to us by Thomas:
“This is the hardware that you need: the basic bits cost about 50 euro plus the power bank(s). All the software is free. And obviously my parabola needs an upgrade 🙂
- Raspberry Pi Zero W – €11
- Micro USB TO USB Cable – €2
- Micro USB TO USB Adapter €3
- UGREEN External USB Sound Card €14
- Lavalier Microphone €10
- Micro SD Card e.g. 32G (24h recording generates about 3.4 GB data) – € 5
- Sealable Food Container € 3
- Power bank 6700 or 10500 mAh, e.g. GOJI – GUP10BK20 € 20
- A new 6700 mAh Power bank would last about 12 hours
What about the sound quality then? Check it out for yourself below. It’s really quite good
So there you have it. It’s possible to record with all manner of devices, cheap and small, large and expensive, and everything in-between. There’s a recording option to suit everyone’s budget s and needs, so why not start?Back to Top