Changes in speed
One of the basic questions we ask of any bird sound is, “are the notes slow enough to count, or too fast to count”? Sometimes, the answer is both.
Some bird sounds change in speed. If the elements in a series are more closely spaced on the spectrogram as you move from left to right, then they are growing more closely spaced in time, which means that the series accelerates. If the elements grow farther apart, the series decelerates.
Here are a couple of examples. The song of the Wrentit is a series of notes that accelerates into a trill, while the drum of a Yellow-bellied Sapsucker starts as a trill of tapping notes, and slows into a series.
Changes in pitch
Phrases, series, warbles, and trills can also change in pitch. For example, a warble might sound upslurred if it shows an overall trend towards higher notes. Similarly, a series might fall in pitch if each note starts slightly lower than the last, even though each individual note may be upslurred.
Changes in both speed and pitch
Many sounds change in speed and pitch at the same time. A quick glance at the spectrogram of the Sora’s whinny shows us that it’s an overslurred, decelerating series with an early peak:
Here’s a decelerating, downslurred series of upslurred whistles:
And here’s a phrase accelerating into an upslurred warble:
Sometimes the repeated elements in a series may themselves consist of multiple notes. A two-noted series sounds like a two-syllabled word repeated, such as “peter peter peter;” a three-noted series, like a three-syllable word repeated, such as “teakettle teakettle teakettle.”
Examples of two-noted series
Examples of three-noted series
Yes, there are four-noted series too
With the basic vocabulary that I’ve introduced in these three posts, we can describe the pattern of almost any bird sound. But there’s more to bird sounds than just pattern. Stay tuned for the next installment in the series.