The Mid-Coast Audubon Chapter asked me to write up a couple of paragraphs on bird sound recording for their newsletter. And, I share it with you all, as well…
An abundance of bird song is what first comes to mind when I think of spring. Why not consider recording it? You likely already have the tools you need to give it a try – your cell phone! Here are some tips I learned from the Macaulay Library at Cornell’s Lab of Ornithology.
1) Download a dedicated recording App (like Voice Record Pro) for your phone that allows you to record using uncompressed WAV files, rather than an MP3 file. While you personally may not hear the difference in the sound files, the latter compresses the file and data will be lost, making it of less value to science as information will be missing which may have been important for science (such as for measurements).
2) So as not to scare off a singing bird, approach slowly, indirectly, and incrementally. It can be hard to guess how close you can get without causing the bird to change its natural behavior. At first, try about 25 meters away (about 80 ft). Using the sound level meter, increase/decrease the gain till the peak range is -6 to -12dB and begin recording. Once you have recorded for at least 30 seconds and up to 2 minutes consider getting closer, or to keep recording. Add a short announcement (species if you know it, behavior, location, time and date). If you decide to try getting closer, aim to halve the distance between the bird and the microphone, as the power of the audio signal will increase by 75% (6dB). But remember, no audio recording is worth causing the bird stress.
3) Once home, download your file. Resist anything more than minor edits. Using free audio software like Audacity, you can trim the ends (to about 3 sec before and after the song). If you want to cut a little bit of low frequency noise (such as distant traffic), you can apply a High-Pass Filter at 60-100Hz, but never more than 250Hz. Then, go ahead and normalize the recording (via “Amplify”); the bird song by -3dB, and your voice announcement by -10dB. Export your modified sound file to save and rename it (something different than your original file), and voila! You are now ready to add your sound recording to your e-Bird checklist!