Dickcissel Night Flights

Thrush

Thrush is PC software that detects short bursts of acoustic energy in the 2.8-5.0 kHz frequency range. It is effective for detecting night flight calls of thrushes and many other species of night migrants in North America. To operate, locate Thrush in an convenient place on your computer (e.g., in the C:\My Recordings folder). Create a folder called "temp" on the C drive and within the "temp" folder create a folder called "calls" [ C:\temp\calls]. Then, create a text file named "stop.txt" on the C drive [C:\stop.txt]. No text need be included in the file. The file name serves as the start and stop button for the software. To start the detection software, change the name of the "stop.txt" file to "go.txt" [C:\go.txt], then double click on the appropriate Thrush icon to begin the program.

There are three versions of Thrush. They are exactly the same except in where they receive inputted sound and how their detected files are named. To download, click on the appropriate link below (each ~400 kb download):

Thrush-o is a version that is used for detecting night flight calls from VCR or other audio recordings. You start the program at the same time you start your audio recording playing into the computer. Detections are copied to wav files in the C:\temp\calls folder and given a file name that contains the word Thrush and then the time of the detection. This time is the time elapsed from when you started the program Thrush-o to when the detection occurred.

Thrush-r is a version that is used for detecting flight calls directly from an active microphone. Detections are copied to wav files in the C:\temp\calls folder and given a file name that contains the word Thrush and then the time on your computer when the detection occurred. If your computer clock is set accurately, then this time will be the time when the call occurred during the night. The date is also included in the file name. Thrush-r is typically used in conjunction with the Windows Task Scheduler for automated nightly call detection (see discussion at end of computer section on the Recording gear page).

Thrush-x is a version that is used for detecting calls directly from a wav file on your computer. To use this version you need to create a folder called My Recordings on your computer's C drive [C:\My Recordings]. Change the name of the wav file that you want to process for calls to Soundfile.wav [C:\My Recordings\Soundfile.wav]. Then, as with the other detectors, change C:\stop.txt to C:\go.txt and double click on the Thrush-x icon. Detections will show up in the C:\temp\calls folder. Processing takes place faster than real time, typically a half hour or so for an 8 hour sound file on a computer with a 1 GHz or faster processor. File names contain the word Thrush and the time of the detection. This time is the time elapsed from when you started the program Thrush-x to when the detection occurred. Note: this software only works on mono, 22050 sampling rate, 16 bit, wav files.

General Information on all Thrush detectors

All the Thrush detectors are very sensitive and will detect any isolated short sound in the 2.8-5.0 kHz frequency range. Therefore, it is important that your microphone be placed in a location that is as far away from singing insects and frogs as possible. A distant chorus is ok, because the individual calls blur together and do not stand out from the background noise. But, distinct calls of many species of insects and frogs will trigger false detections. Some loud insects or frogs can be 50+ meters from a microphone and still trigger a detection. The presence of singing insects or frogs may result in thousands of false detections in an evening. The small frog called the Spring Peeper Hyla crucifer, which is common across much of eastern North America, is a frequent source of false detections. Their common vocalization is very similar to the flight call of the Swainson's Thrush and can even be confused with Swainson's Thrush.

All the Thrush detectors produce a text file in the C:\temp\calls folder with a logarithmic index for variation in hourly sound energy in the 2.8-5.0 kHz frequency band. The file name is LogThrush.txt.

All the Thrush detectors have an automatic shutdown mode that is triggered when 10 or more detections occur within 20 seconds. This, to some degree, prevents massive numbers of false detections due to rain drops, continuous song from insects and frogs, or mechanical noises. The detection operation resumes again as soon as the program sees that detections fall below 10 in 20 seconds.