Audio recording tips for eBird
Hi all. It’s becoming increasingly common for folks to submit audio recordings to help document their sightings in eBird, so I thought I’d offer a few tips on how to maximize the usefulness of your recordings.
First, smartphone mics are optimized for loud sounds at close range, so they will do an excellent job picking up handling noise and the sound of the wind blowing across the mic, but will be much less effective at capturing more distant bird sounds. So as you are about to start recording, get your phone in a comfortable position (with the microphone pointing at the bird!), and try to hold it steady with minimal movement. Avoid introducing extraneous noises, such as from talking (even in a whisper) or walking. If the bird is a bit distant or the vocalization is weak, it’s fine to capture an initial recording in case the bird flies off, but then get as close as possible so you can maximize the signal-to-noise ratio. Because sound radiates in all directions, the sound intensity follows the inverse square law, meaning that if you cut the distance in half, the sound intensity will be quadrupled. Moving even a little bit closer can make a big difference. Just because you can hear the sound clearly doesn’t mean your phone will pick up all of the essential details. If there is any wind, try to use your body or some other object as a windshield. Another good technique is to hold the recorder close to the ground – the wind is generally much calmer at ground level.
Second, aim for getting at least a minute of audio that is free of handling noise. Recordings as short as 5 to 10 seconds are often submitted, but these have little value to researchers and are rarely adequate to document a rare bird sighting. In addition to the length of the recording, pay attention to the number of vocalizations. It’s always best to capture a long series of calls or song phrases. If the bird is vocalizing infrequently, don’t hesitate to get several minutes of audio.
eBird best practices call for the handling noise to be edited out and the recording to be amplified to a peak of – 3dB. There are free audio recording and editing apps for iOS and android phones that can make this fairly easy. If you prefer recording in Merlin, you can export those recordings to your desktop computer and edit them in free software like Audacity. The eBird help pages have additional recording tips you can find here: Smartphone Audio Tips.
Finally, if you are inclined to rate your own recordings or those of others, please review the rating guidelines here: Audio Rating Guidelines. Accurate ratings are important to researchers as well as regular eBird users searching the archives for high quality recordings. If you would like to see examples of appropriate ratings for audio files, check out the recordings here: Rating examples. These are from one of the best sound recordists in the country, and he always rates his own recordings accurately. You might be surprised at what merits a 2 or 3 star rating!
Thanks, and good birding,