In my PhD thesis and in the paper Detecting bird sounds in a complex acoustic environment and application to bioacoustic monitoring, I have proposed a simple yet robust algorithm for automatically detecting calls of the Eurasian bittern in the wild.
The Eurasian bittern is a threatened bird species found in reed beds and other wetland habitats. Its sound is very simple, very deep, and very characteristic. It is pretty similar to what you can produce by blowing over the opening of an empty bottle (use a large one) in regular intervals.
Recently, I have been asked whether I still have the Matlab code for the algorithm. A bit of digging on an external hard drive has shown that I indeed still have it.