Bird songs and calls are as significant as field marks for identification, and recognizing birds by sound is arguably the most challenging skill in birding. Yet birders have had little option but to memorize songs, until the introduction of the spectrogram—a visual graph of sound that shows speed, repetition, pauses, pitch pattern, and tone quality. The spectrogram is at the core of this essential Peterson field guide, making it possible for readers to visualize sounds and search the book for any song heard in the field. You can also compare the spectrograms to audio recordings available online through Cornell's Lab of Ornithology.
Peterson Field Guide To Bird Sounds Of Western North America
Author: Nathan Pieplow.