Last summer(2018) I deployed a simple audio recording device in our yard to sample the sounds of that ecosystem for thirty seconds every thirty minutes. Over the monitoring period from early in May through the end of October I accumulated around 8800 audio files. These were automatically analyzed and uploaded to a page on this website as they were recorded.
The images below are of a kind of pseudo-spectrogram, in the sense that it is irregularly sampled, built up from the power spectral density calculations for each thirty second recording for an entire month. I like these graphics because they show the general rhythms of the ecosystem. (click on any graphic for a larger view)
In May and June one can see the diurnal rise and fall of bird song. In early May, perhaps the evening calls of frogs and toads down at the pond. Then in mid-July the beginning of the most striking feature of these records, the appearance of the songs of the summer insects and the diurnal frequency changes with species and air temperature. In the fall months, one can see the tapering away of the insect sounds punctuated by abrupt changes caused by foul weather.
Over the next several weeks I hope to do a series of posts with more details in each month. I will also be making some changes to the recording hardware and software with the goal of getting two recorders out this year and earlier in the spring.