If you already have a computer, adding a microphone that you can put outside is probably one of the easiest ways to start nocmig recording. Although many computers have a 3.5mm line-in socket, the internal sound card that processes the incoming audio can add a lot of noise to recordings. You’re probably better off going for a USB microphone. For as little as £12 you can get a basic USB microphone typically used for video conferencing, or you can spend more and get something that will produce higher quality recordings. Its worth adding a 10m USB extension cable to give greater flexibility over where you place the mic. Better quality USB mics will give higher quality recordings, as detailed below. The main drawback of using a USB mic is the need to have power to run a computer through the night, which may limit use in some locations.
The one pictured here is a Kinobo mini “AKIRO” USB microphone. There are lots of variants on this basic theme. They’re c7cm long and come with a 1.5m cable. These are cheap and of variable quality but can give good enough results to see what’s going over your location and whether its worth investing time and money in more serious recording efforts.
The spectrogram below, of Blackbird alarm calls at dusk, was made using a £10 mini USB in a mixing bowl. This mic produced visible artefacts at 4kHz and 8Khz (dark blue lines) and the banding in the lower frequencies is probably due to the incorrect shape of the “parabola” (aka mixing bowl) incorrectly focusing sound waves. A mini USB with a proper parabola would probably work pretty well. Regardless, the calls are easily visible and this setup got SG his first Moorhen and Water Rail, and an Ortolan Bunting…
If you want greater sensitivity and higher quality recordings one option is the Yeti range of USB microphones produced by Blue. SG used one of these for 6 months and recorded a wide array of migrants. The image below shows a Yeti mic sealed in a plastic waste pipe with a salad bowl for reflector and cling film rain cover.
The sound quality with the Yeti mic is excellent. Here is a recording of a Coot using this setup:
And here is the corresponding spectrogram: