Moonlight diminishes seabird attraction to artificial light

Rescue programs aiming to mitigate light-induced mortality of seabird fledglings have reported that fewer birds are grounded (and rescued) during full moon nights. Two non-mutually exclusive hypotheses have been proposed as explanations: (1) reduction of strandings because birds are less attracted to and disorientated by light pollution during full moon nights; and (2) reduction of fledging activity, that is, chicks avoid departing the colony during nights with increased moonlight. We argue that evidence from rescue programs and other studies supports the first but not the second hypothesis. The evidence supports the conclusion that a higher proportion of fledglings make it safely to sea during full moon nights than during moonless nights. Thus, there is a decrease in the severity of light pollution on seabirds around the full moon. Rescue programs aiming to mitigate light-induced mortality of seabird fledglings have reported that fewer birds are grounded (and rescued) during full moon nights. Two non-mutually exclusive hypotheses have been proposed as explanations: (1) less attraction to and disorientation by light pollution during full moon nights and (2) reduction of fledging activity. Evidence from rescue programs and other studies supports the first but not the second hypothesis. Thus, a higher proportion of fledglings make it safely to sea during full moon nights than during moonless nights, with a diminished severity of light pollution on seabirds around the full moon.image