Data from: Shedding light with harmonic radar: Unveiling the hidden impacts of streetlights on moth flight behavior

One of the most dramatic changes occurring on our planet is the
ever-increasing extensive use of artificial light at night, which
drastically altered the environment to which nocturnal animals are
adapted. Such light pollution has been identified as a driver in the
dramatic insect decline of the past years. One nocturnal species group
experiencing marked declines is moths, which play a key role in food webs
and ecosystem services such as plant pollination. Moths can be easily
monitored within the illuminated area of a streetlight, where they
typically exhibit disoriented behavior. Yet, little is known about their
behavior beyond the illuminated area. Harmonic radar tracking enabled us
to close this knowledge gap. We found a significant change in flight
behavior beyond the illuminated area of a streetlight. A detailed analysis
of the recorded trajectories revealed a barrier effect of streetlights on
lappet moths whenever the moon was not available as a natural celestial
cue. Furthermore, streetlights increased the tortuosity of flights for
both hawk moths and lappet moths. Surprisingly, we had to reject our
fundamental hypothesis that most individuals would fly towards a
streetlight. Instead, this was true for only 4% of the tested individuals,
indicating that the impact of light pollution might be more severe than
assumed to date. Our results provide the first experimental evidence for
the fragmentation of landscapes by streetlights and demonstrate that light
pollution affects the movement patterns of moths beyond what was
previously assumed, potentially affecting their reproductive success and
hampering a vital ecosystem service.