During the last year or two, the value of sound recorders as an essential field tool has become more recognised than ever before in British birding. This usage has, largely, been twofold: nocturnal sound recording (noc-mig) has, after steadily becoming more 'mainsteam' over the past two years, enjoyed a remarkable spike in uptake terms. Lockdown and the subsequent limit on birders' movements no doubt played a part in this. Almost in tandem has been the increase in people carrying sound-recording gear in the field, whether to specifically record birdsong and calls or to try and document a rare or unidentified bird (the Cornish Paddyfield Pipit being one such example).
Continuous sound recording in the day – we'll call it CSR in this article – is by no means a new concept. But, while it is practiced in Britain, I am always surprised at how so few people are doing it. Until recently this includes myself, as it wasn't until I first dabbled in noc-mig a few years ago that I realised I was missing a trick by not recording continuously during daytime field sessions.
What is CSR and why is it useful?
CSR is rather like 'noc-migging' during the day: keeping a recorder running while you go about your birding, in order to document every song or call heard while you're in the field. In a similar vein to noc-mig, CSR will pick up that calling flyover whenever it occurs – there's no need to worry about switching your recorder on and hoping you have time to pick up the bird in question before it's gone. In short, you won't miss with CSR, but turning the recorder on each time you want to document something will inevitably result in many flyovers slipping through the net.
A recording of a flyover Grey Wagtail, obtained passively by continuous sound recording while in the field. While this species may not be of note in most places, if the wagtail moving overhead was Citrine, then CSR would have captured proof of identity vocalisations (Ed Stubbs).
With flyovers perhaps the main reason for someone to consider CSR, let's take a closer look at the benefits. I write this in mid-September – peak autumn migration is upon us and, for the next couple of months, many birders will be getting up at the crack of dawn and heading into the field, whether to undertake visible migration (vis-mig) at a favoured watchpoint, bush bashing along the coast and everything in between. In any of these scenarios, a fleeting flyover can catch you off guard, whether a Richard's Pipit flushed from a beach dune or a Lapland Bunting bombing over an inland hill. With CSR, these species and their distinctive calls are nailed – even if you've got the briefest or poorest view imaginable – and documented for good measure.
Whether you want to confirm the ID to yourself or are providing a description of the event to a rarities committee, the recording and sonogram – hard evidence – is there. Often there is hardly any time to think, let alone act, with unexpected flyovers and CSR thus proves an assurance tool. It's not always easy to describe bird vocalisations in an authentic way and, furthermore, exactly how a call sounded can erode in your mind over time. Also, if you've heard a call that left you unsure, CSR allows you to go back through it and pick away – I've often found that a bird has called a few times more than I thought it did in the field, as well.
How to CSR
Depending on how you're birding during a particular session, there are two main ways to CSR. For most field sessions, it's preferable to have the sound recorder on you in person. This means you're recording as you move around, with the recorder picking up the calls you hear. How you do this depends on your setup. I often just use my sound recorder, with no shotgun microphone attached (unlike my noc-mig set up). This is fitted with a small wind muff, which is rather important in regard to reducing wind noise and other man-made sounds.
This Hawfinch was recorded via a stationary setup at Portland Bird Observatory, Dorset, with the excitement of observers and camera shutters also picked up (Joe Stockwell).
I've tried all manner of ways to fit the recorder to my person – from masking tape to bandanas! – but have found a handy solution, which is placing the recorder inside the mesh drinks holder on the side of my Karrimor rucksack. As the drinks holder is bigger than my recorder, I pad it out in order to reduce movement. My recorder (Olympus LS-P4) comes with an in-built directional microphone, which means I don't need to use an external shotgun or similar – it records 'upwards' (thus reducing the noise of footsteps etc and enhancing overhead sounds). Other options include safety clips, a breast pocket on a jacket, gaffer tape, straps on your wrist akin to a watch – whatever works for you is the way to go, but it will probably take a few sessions of trial and error.
However, many popular recorders with birders don't have the in-built directional microphone and so hugely benefit from an external, directional microphone. Mark Lewis, who has written an excellent page on CSR (or, in his words, 'passive acoustic birding') here, explains his sound recorder and external microphone setup: "I use a Zoom H4N Pro recorder and a Rode NTG4 microphone that is constantly running for CSR.
CSR isn't just useful for flyovers. This calling Red-breasted Flycatcher was documented as soon as he heard it and before it was seen. You can also hear the finder pishing! (Mark Lewis).
"I wear this in a harness that sits on my shoulder – it's nothing more than a sock shape with a strap attached – and to keep the mic in place I wrap the slack from the strap around my rucksack shoulder straps. This keeps the mic pointing upwards and both hands free, and allows me to access it quickly to point at birds singing or calling from land.
"If I hear anything of significance while birding I simply note the time on the recorder and skip straight to that when I'm looking at the recording later on. Even if nothing interesting flies over, having the recorder running constantly allows me to get some really nice recordings at ground level.
Mark's setup, including a harness which supports a shotgun microphone which faces up, picking up overhead calls and keeping his hands free to point it in any direction necessary (Mark Lewis).
"So far this method has helped me confirm badly heard flyover Red-throated Pipit and a distant calling Siberian Chiffchaff, nail the ID of flyover Woodlark, and meant I was ready to record an unseen calling Red-breasted Flycatcher and a Blyth's Pipit that was flushed by birders. None of these calls would have been recordable if I hadn't had the equipment ready and running.”
... and the CSR recording Mark obtained when it was (Mark Lewis).
The other way to CSR is a stationary setup. This is ideal if you're vis-migging and are essentially not moving – perhaps doing a watch from a headland or hilltop. It's just like a noc-mig setup: having the recorder facing upwards and running (with or without an external, directional microphone) while you stand near it. There are plenty of ways to do this, but I have found that strapping the sound recorder to a microphone stand, with a directional microphone at the top of the stand facing up, is by far the best way for clear results of overhead birds.
The steadiness a stand brings helps with sound quality, too. To be honest, given the number of dedicated vis-miggers in Britain, I'm surprised there aren't more people recording like this. It's the perfect safety net for capturing that rare flyover. I spend many hours vis-migging in my local area in Surrey and last autumn CSR captured a flyover Red-throated Pipit over my patch. I failed to photograph the fast-moving bird (despite my best efforts, which you can hear in the recording!), but the sound recorder nailed it, both documenting the bird and creating a wonderful personal keepsake for me.
A flyover Red-throated Pipit recorded via CSR during a stationary vis-mig in Surrey (Ed Stubbs).
Joe Stockwell often practices CSR while he vis-migs in Portland, Dorset, and he offers his thoughts: "It wasn’t until I discovered noc-mig and how to process recordings in bulk that I thought I should be doing this by day too. I knew it wasn't a new thing by any stretch, but until I did it the worth hadn't become apparent. 2017 saw me take time out from a busy work schedule, one which I never returned to following on from having such an awesome time. Most mornings were spent either wandering the fields of Portland or vis-migging from the patio at the observatory with Martin Cade and Grahame Walbridge.
"I started to leave a recorder running from start to finish, normally about 10 metres away from us, in the hope that anything we heard and saw would be recorded. Starting out this was fairly basic: a Tascam DR-05 recorder and cheap shotgun microphone from Amazon. As with my early nocturnal recording, this setup was actually really good. Later that autumn a rather large sum of money was sent to Sweden and a few weeks later a Telinga Pro-X parabolic dish setup arrived. This changed not only how good my recordings now were, but also how much more I began to pick up, long before any of us would make the call.
"Nowadays I like to vis-mig away from the patio to make sure any recordings I do make are clean. The last thing I'd want is a flyover Blyth's Pipit with various observer's commentary trying to figure out its identity, no matter how entertaining that could sound!"
A stationary setup, featuring a Telinga Pro-X parabolic dish that picks up every overhead call (Joe Stockwell).
Power and processing
An issue I encountered early on with my CSR experimentation was power, or rather a lack of. I often use my recorder on the back of a night of noc-mig – there isn't enough time between my bleary-eyed awakening and stumbling out the front door for the recorder to fully charge. Often, my recorder can battle on an hour or so post-noc-mig, but it's recommended to obtain a power pack. Much like one you'd use to portably charge your phone, it can give your sound recorder a new lease of life ahead of a CSR session. A good power pack will keep it charged for at least 12 hours, I've found.
A busy dawn migrant finch soundscape at Portland, including Brambling, Chaffinch, Goldfinch and Linnet (Joe Stockwell).
As Mark mentioned earlier in this article, it's easy to note down the time you've heard something, so that you can quickly find it when processing the recordings on software later on. I actually speak into the recorder once a bird or call of note has occurred, stating the species, call-type and time – a close-range human voice stands out like a sore thumb on a sonogram.
It's worth pointing out that the quality of CSR recordings can often be middling or even poor. A bird can flyover whenever, so all sorts of background noises can be going on and, especially if you’re not birding alone, human voices can be an issue. Wind is an important factor, too. One thing I do to minimise poor quality is more or less 'freeze' when I suddenly hear a decent bird, so footsteps and movement cease as soon as possible. This process can actually be heard in one of Mark's recordings below.
The rattling trill part of this Lapland Bunting call is distorted by the sound of the observer's movements, but by stopping still, the 'peu' part can be heard clearly (Mark Lewis).
So, for anyone who has a sound recorder and hasn't yet considered CSR, I highly recommend giving it a go when you're out in the field this autumn. Not only will it automatically record calls you'd struggle to nail if recording 'manually', it also could prove crucial in nailing that rare flyover or probable vocalisation that you weren't 100% certain of at the time. It's a straightforward concept really and doesn't require much ingenuity to manufacture a setup that suits you. Sometimes a flight call is all you'll get on a class bird, so it's surely worth being assured that you'll document it.