International Dawn Chorus Day celebrates the morning symphony of song that birds use to maintain territory, attract or guard mates, or strengthen pair bonds. Environmental factors such as cloud cover, precipitation, moon phase, and temperature can affect the onset of the dawn chorus, as can an individual bird's breeding phase. The specific impacts of these factors on the dawn chorus are not fully understood, and there is evidence that responses differ between species and individuals.
The Haikubox network captures bioacoustic data that reveals patterns and trends in bird behavior. Haikuboxes automatically and continuously identify birds using sound, record sound clips, and count the identified species. This has created, and will continue to build, a massive dataset of bird vocalizaations. This kind of passive acoustic monitoring (PAM) can be used for a variety of scientific studies.
A preliminary review of the Haikubox data showed interesting variation between American Robin vocalizations at different locations.
The top heatmap of American Robin vocalizations at one Massachusetts location clearly shows the dawn chorus occurred between March and July 2022, with a strong but brief dusk chorus from March through May 2022. Brighter colors indicate more birdsong, and the chorus timing changes as days get longer leading up to the summer solstice, and then shorter again. Each heatmap square represents 15 minutes, when between 0 and 100+ American Robin vocalizations were identified.
The second heatmap shows American Robin vocalizations at a different Haikubox site, this one in Washington state. While the dawn and dusk chorus are also visible, these birds finished vocalizing in late June and vocalized more during the heart of the day. A third Haikubox in Utah shows almost no sign of a dusk chorus, but a more intense and shorter period of dawn chorus.
Many questions remain and additional Haikubox sites will be investigated, as will other bird species. Multi-year comparisons may shed light on whether there are persistent environmental factors at work.