I discovered that now exist an app that permit to recognize birds simple listening to their chants.
For the moment it is only for ipad/iphone and it is not for free:
Here it is a more verbosely explanation:
"Song Sleuth turns your iPhone or iPad into an automatic bird song identifier covering the 200 most common vocalizing land birds in the U.S. Developed by Wildlife Acoustics, in collaboration with world-renowned bird expert and illustrator David Sibley, the app records bird songs and suggests likely matching species. The identification algorithms are the result of over a decade of research and experience designing professional bioacoustics recorders and software.
Not just for beginners, the app also has features for intermediate birders who might need an identification hint or wish to study the included example recordings to take their ear birding to the next level. Advanced birders who don’t need any identification help will appreciate the ability to make and keep recordings for further study."
