Data from: Chronic exposure of Hawaii Island spinner dolphins (Stenella longirostris) to human activities

Habitat selection is strongly influenced by spatial variations in habitat
quality and predation risk. Repeated exposure of wildlife to anthropogenic
activities in important habitats may affect habitat selection, leading to
negative biological consequences. We quantified the cumulative human
exposure of a small, genetically-isolated and behaviourally-constrained
spinner dolphin (Stenella longirostris) population, off Hawaii Island, and
exposure effects on their daytime cumulative activity budget. Dolphins
were exposed to human activities within 100m for 82.7% of the daytime,
with a median duration of 10 min between exposure events. Individual
dolphins spent on average 61.7% (SD=6.5) of their daytime resting. Of
their total rest time, >90% occurred inside sheltered bays. Despite
high levels of human exposure, we did not observe an effect on dolphin
resting behaviour. The short intervals between exposure events likely
prevent dolphins from returning to a natural resting state before the next
event. Consequently, ‘control’ observations may represent a resting
behaviour of a more vigilant nature. Chronic levels of exposure to human
activities could lead to rest deprivation, displacement from preferred
resting habitats and ultimately negative population level effects. These
results have implications for new proposed legislation aiming to reduce
dolphin exposure to human activities.