New biologging approach reveals unique flightless moult strategies of
Atlantic puffins
Abstract
Animal-borne telemetry devices provide essential insights into the
life-history strategies of far-ranging species and allow us to
understand how they interact with their environment. Many species in the
seabird family Alcidae undergo a synchronous moult of all primary flight
feathers during the non-breeding season, making them flightless and more
susceptible to environmental stressors, including severe storms and prey
shortages. However, the timing and location of moult remains largely
unknown, with most information coming from studies on birds killed by
storms or shot at sea. Using light-level geolocators with saltwater
immersion loggers, we develop a method for determining flightless
periods in the context of the annual cycle. Four Atlantic puffins
(Fratercula arctica) were equipped with geolocator/immersion loggers on
each leg to attempt to overcome issues of leg-tucking in plumage while
sitting on the water, which confounds the interpretation of logger data.
Light level and saltwater immersion time-series data were combined to
correct for this issue. This approach was adapted and applied to 40
puffins equipped with the standard practice deployments of geolocators
on one leg only. Flightless periods consistent with moult were
identified in the dual-equipped birds, whereas moult identification in
single-equipped birds was less definitive and should be treated with
caution. Within the dual-equipped sample, we present evidence for two
flightless moult periods per non-breeding season in two puffins that
undertook more extensive migrations (> 2000km), and were
flightless for up to 76 days in a single non-breeding season. A biannual
flight feather moult is highly unusual among non-passerine birds, and
may be unique to birds that undergo catastrophic moult, i.e. become
flightless when moulting. Though our conclusions are based on a small
sample, we have established a freely available methodological framework
for future investigation of the moult patterns of this and other seabird
species.