Under cover of darkness: Refuge from artificial light at night may mitigate risks to stranded seabirds

Artificial light at night is an anthropogenic pollutant that has
wide-ranging effects on wildlife. Fledgling seabirds of order
Procellariiformes exhibit phototaxis toward artificial lights on their
first flights from the nest, causing them to become grounded in human
settlements, where they are subject to increased predation risk. Limited
evidence suggests certain light types may be less attractive than others,
yet there is also evidence for an aversion to light under certain
circumstances. We investigated differences in phototactic behaviour,
activity level, and shelter-seeking behaviour of grounded Hydrobates
leucorhous (Leach’s storm-petrel) fledglings exposed to artificial light
in three experiments: a Y-maze choice experiment, an open field test, and
a modified open field test with a hide box provided (“Safe Haven test”).
When provided with combinations of different light types in the Y-maze,
storm-petrels typically remained stationary in the darkest parts of the
apparatus (farthest from light stimuli) and exhibited no preferred
response toward one light type over another. This was consistent with
results from the open field test: individuals were less active in darkness
than when exposed to two of three light conditions (Warm White
Light-Emitting Diode and High Pressure Sodium). More than half of
individuals entered the hide box in light conditions, compared to none in
darkness. Considered together, our results indicate that most (but not
all) Leach’s storm-petrel fledglings exhibit photophobic behaviour after
stranding, which may be part of a behavioural strategy to avoid predation.
Further, we demonstrate the utility of providing hide boxes to protect
stranded seabird fledglings in locations where lighting cannot be
eliminated or where rescue efforts are limited in spatial or temporal
coverage. However, hide boxes would have limited utility in dark
locations. Hide boxes constitute a novel mitigation measure that merits
future testing for its ability to reduce stranding-induced mortality,
especially in imperiled procellariiform species.