5 December 2024
Crows are so vocal that we can’t help but think their caws are a language. So what are crows saying in their big boisterous flocks before they roost?
Dr. Douglas Wacker at University of Washington Bothell (UWB) wondered the same thing so in 2017 his team began recording and analyzing pre-roost aggregations on the UWB roofs. The rooftop recordings were not enough to crack the code so now the team has turned to spectrogram analysis.
Dr. Wacker presented information on crow vocalizations at the Olympic Peninsula Audubon Society in November 2024. To measure the calls they analyzed these components.
- Syllable = a single caw
- Gap = the length of silence between caws
- Call = a series of caws
- Pause = the length of silence between calls
The team recorded crow vocalizations in various contexts and compared the spectrograms. And they discovered an unusual thing. Crows appear to be “saying” things in the silence between their caws (gaps) and the pauses between their calls.
- Gaps between caws: Are longer in pre-roost aggregations (evening) than in post-roost aggregations (morning).
- Pauses between calls: Are shorter while mobbing an owl than in pre-roost aggregations.
If you want to know what a crow is saying, listen to their silences.
Learn more about crow language in this Olympic Peninsula Audubon Society’s video. I have set it to start nearly an hour into the meeting, beginning with spectrogram analysis of crow calls. I’ve included this 15 minute portion here because it is so interesting. Click here to see the entire 1.5 hour meeting.
Some day we might know what this crow is saying. In the meantime, listen to the gaps.
p.s. Dr. Wacker described an intriguing idea: The messages in human language come from our sounds. The messages in crow language appear to come from silences. Perhaps we can’t figure out what crows are saying because we aren’t used to listening to the silences.