Bird Behaviour during the June 21, 2020 Solar Eclipse

Abstract

Background: A solar eclipse is an occasional natural phenomenon that can alter the physical and biological processes of organisms. On 21 June 2020 a unique opportunity was offered to evaluate how birds change their behaviour during an eclipse. Bird behaviour was categorised using a scan-sampling technique before, during and after the solar eclipse, and at a different time of eclipse day. Results: Before the eclipse major activity categories were moving (52.45%), foraging (40.20%), and courtship (2.94%) respectively, but there were no roosting/resting observations at this time. These behaviours were much reduced during the eclipse, while roosting accounted for 14.6% of behaviour. When the eclipse began at 06:50, their calling and flying increased, and singing decreased. At maximum eclipse (07:20h), there was a profound decrease in calling, singing, foraging and moving, and courtship; while washing and floating were not observed. After the eclipse, most time was spent foraging (36.3%), followed by moving (flying), with roosting reduced to 2.4%. Conclusions: Clear and radical behavioural changes were observed when the eclipse was started and maximum. Responses of birds to the environmental factor changes associated with the solar eclipse might be the root cause of observed unusual behavioural change.

Solar Bird Banding: Notes on Changes in Avian Behavior While Mist-netting During an Eclipse

“…The positive relationship we found in bird movements during the eclipse runs counter to behavioral responses of birds in prior studies, which noted declines in overall activity and movements of birds during eclipses (Tramer 2000; Nilsson et al 2018; Wiantoro 2019; Mekonen 2021). Three of these studies though were observational in nature rather than relying on data collected from a rigorous methodology (Nilsson et al 2018), like bird banding.…”

“…observation of the authors). This decrease in avian vocal activity during the height of the eclipse mirrors trends reported in some prior studies (Mendoza 2018; Mekonen 2021), but differs from another that saw an increase in vocalizations (Brinley Buckley et al 2018). These differences in vocal responses could be driven by phylogeny and species-specific behavioral cues for vocalizing (Brinley Buckley et al 2018), with some species more inclined to vocalize than others in response to photic disturbances or lower light levels.…”

“…Birds may have been imitating their typical end-of-day behaviors when confronted with the sudden onset of darkness from an eclipse. As peak totality approached, birds could have been moving around more in order to return to or find a place to roost (Van Doren et al 2017; Nilsson et al 2018; Mekonen 2021), thinking that dusk was occurring; the mist-nets therefore could have prevented these birds from reaching intended roost spots to remain relatively inactive for the remainder of the eclipse, in which case trends in activity would have been more similar to those found in other studies. On the other hand, the unusual nature of the eclipse occurring during the day could have caused birds to become disoriented and move around in a chaotic and stressed manner.…”

“…Due to the infrequency of these celestial events, there are limited opportunities to comprehend the distinctiveness of biotic effects from each occurrence, given the variations in timing, locations, and atmospheric conditions. Consequently, this infrequency of solar eclipses in North America is compounded by a dearth of structured data collection, such as from bird banding or soundscape recordings, of birds in the field during these events to aid in our understanding of bird behavior during eclipses to changes in light conditions (but see Mendoza 2018;Nilsson et al 2018;Brinley Buckley et al 2018;Mekonen 2021).…”

“…For instance, several studies have noted unusual behavior amongst avian species in response to solar eclipses. During a solar eclipse in Central Ethiopia in 2020, there was a profound decrease in calling, singing, foraging and moving, and courtship behavior amongst the birds observed (Mekonen 2021). Likewise, some birds significantly altered their vocalizations during the 2017 eclipse in the United States (Brinley Buckley et al 2018).…”