Data and code to explore annual cycle schedule adjustments in a long distance migrant

Matching the timing of annual cycle events with the required resources can
have crucial consequences for individual fitness. But as the annual cycle
is comprised of sequential events, a delay at any point may be carried
over to the subsequent stage (or more, in a domino effect) and negatively
influence individual performance. To investigate how migratory animals
navigate their annual schedule, and where and when it may be adjusted, we
used full annual cycle data of 38 Icelandic whimbrels Numenius phaeopus
islandicus tracked over 7 years –  a subspecies that typically
performs long-distance migrations to West Africa. We found that
individuals apparently used the wintering sites to compensate for delays
that mostly arose due to previous successful breeding, and a domino effect
was observed from spring departure to laying date, with the potential to
affect breeding output. However, the total time saved during all
stationary periods is apparently enough to avoid interannual effects
between breeding seasons. These findings highlight the importance of
preserving good quality non-breeding sites in which individuals may adjust
annual schedules and avoid potentially adverse effects of arriving late at
the breeding grounds.