The red-necked nightjar's entire annual cycle is paced by a 29-day lunar rhythm, according to researchers at Lund University [1].
This discovery reveals how celestial illumination directly dictates the energy balance of nocturnal species. Because these birds rely on moonlight to hunt insects, the lunar phase determines their ability to survive and reproduce.
Researchers conducted field work across southern Europe and Africa to track the birds in their breeding and migratory habitats [2]. The long-term study, published in May 2026 [3], found that the species uses the moon as a primary biological clock. This illumination provides the necessary light for the nightjar to forage effectively at night [4].
According to the study authors, moonlight determines when the red-necked nightjar feeds, migrates, and raises its young [5]. The researchers said that the bird's foraging success is tied to the lunar illumination pattern, which in turn underpins its overall energy budget [4].
One author of the Science Advances article said the bird’s entire life runs on a 29-day lunar clock [1]. This rhythm affects not only daily hunting but also the timing of long-distance movements and the care of offspring.
By monitoring the birds over multiple years, the team established that the lunar cycle is the dominant driver of the species' behavioral patterns [3]. The findings highlight a precise evolutionary adaptation where a bird's survival is linked to the phases of the moon.
“The bird’s entire life runs on a 29-day lunar clock.”
This research demonstrates a strict biological dependency on lunar cycles, suggesting that nocturnal migratory birds may be more vulnerable to light pollution. If artificial light disrupts the natural lunar cues these birds rely on for energy management, it could negatively impact their migration timing and reproductive success.
