Thu, Aug 18, 2022: 5:00 PM-6:30 PM
ESA Exhibit Hall
Background/Question/Methods: Light cycles control the timing of daily activities that can affect the success of an organism. While rhythms entrained to solar cycles are well understood in diurnal animals, we know less about how lunar light affects most organisms. Some research has found lunar rhythms influence diurnal vertebrates’ life history, hormone levels and mating success. However, little is known about the impacts of lunar light on parental care, a key element of reproductive performance. We studied the relationship between moonlight intensity and the timing of offspring provisioning in Tree Swallows (Tachycineta bicolor) by tracking adult nest box attendance over several breeding seasons in three locations: New York, California and Alaska.
Results/Conclusions: We found that birds in all three locations had shifted behavioral patterns that correlated with the lunar cycle. Both male and female parents began provisioning offspring later on days following brighter moons, which resulted in shorter days of provisioning overall in New York and California birds. In contrast, the Alaska swallows began provisioning earlier following bright nights and foraged for longer periods that day. These results point to latitudinal signals and associated daylength affecting birds’ relationship with moonlight, with lower latitude, shorter day birds avoiding moonlit dawns, and high latitude, long day birds using moonlight to forage longer. As a whole this study found that diurnal animals, including cavity-nesting birds, are influenced by the lunar cycle. These findings exemplify the importance of understanding how moonlight influences the behavior of breeding birds and the continuing importance of studying lunar rhythms in a diverse panel of organisms.
Results/Conclusions: We found that birds in all three locations had shifted behavioral patterns that correlated with the lunar cycle. Both male and female parents began provisioning offspring later on days following brighter moons, which resulted in shorter days of provisioning overall in New York and California birds. In contrast, the Alaska swallows began provisioning earlier following bright nights and foraged for longer periods that day. These results point to latitudinal signals and associated daylength affecting birds’ relationship with moonlight, with lower latitude, shorter day birds avoiding moonlit dawns, and high latitude, long day birds using moonlight to forage longer. As a whole this study found that diurnal animals, including cavity-nesting birds, are influenced by the lunar cycle. These findings exemplify the importance of understanding how moonlight influences the behavior of breeding birds and the continuing importance of studying lunar rhythms in a diverse panel of organisms.