Sunday, April 17, 2011

Steve's Owl Recorder- the technical side of monitoring

Steve King is one of the owl project's dedicated volunteers and brings his technical expertise to our program. Steve set up a remote broadcasting and recording device on the Big Chico Creek Ecological Reserve (BCCER) that he can monitor from his computer at home. Here is how he explains it.

The owl recorder is a device that can play a bird or owl call (in this case a N. Saw-whet Owl) and then record for a period of time after. The recorder can run completely unattended or can be commanded to play specific calls and record from anyplace with Internet service. The idea was to help us better understand when the Northern Saw-whet owl arrives and/or passes through the BCCER during migration. It was designed using a small low power computer. A USB audio input and output device was connected and a audio amplifier was also added that was capable of driving outdoor speakers. The picture above shows the recorder (and Steve) with the antenna on top, computer in the white box and the speakers down below. The battery is on the ground and the solar panel is behind the camera in a sunny location.

The call is played for 15 to 30 seconds and the recording is started right after the call ends. The time of the recording can vary. Once the recording is completed, it is sent to another computer over a wireless connection. The second computer is a little more powerful and it converts the audio wave file recording to a MP3 file and also creates a spectrogram of the audio recording. The spectrogram and recording are uploaded to a web page where we check for sounds. We can look at the spectrogram to determine if any sounds are on the recording. Below is a spectrogram after playing a Saw-whet Owl call, which shows a Saw-whet responding in a series of toots. The spectrogram and recording below was made in April of 2011.

Follow this link if you would like to hear the audio for the spectrogram. This was the latest detection for a Northern Saw-whet owl on the reserve for this season. There was a little wind that night, which shows up on the right of the spectrogram. There is also a highway in the area.

Pretty cool stuff! (comment by D Garcia)