When the Too-Early Bird Sings

(National Geography, Arnaud Da Silva, Mihai Valcu, and Bart Kempenaers, Max Planck Institute for Ornitholog; 2018)

In spring songbirds greet the rising and setting sun with a cacophony
of chirps meant to entice mates and claim territory. But artificial light
has made the night sky brighter and disrupted the seasonal rhythms
of birds that use day length as a cue to sing. Of six songbird species
that scientists studied in Germany, four started singing earlier in the year
because of night lighting. The long-term effects of light pollution on
birds’ ecosystems, and their survival, remain unclear.