Sergio, F., Taferna A., De Stephanis, R., López Jiménez, L., Blas, J., Tavecchia, G., Preatoni, D., and Hiraldo, F., 2014: 'Individual improvements and selective mortality shape lifelong migratory performance'. Nature. doi:10.1038/nature13696
Billions of organisms, from bacteria to humans, migrate each year
and research on their migration biology is expanding rapidly through ever more sophisticated remote sensing technologies. However, little is known about how migratory performance develops
through life for any organism. To date, age variation has been almost
systematically simplified into . These comparisons have regularly highlighted better migratory performance by adults compared with juveniles,
but it is unknown whether such variation is gradual or abrupt and
whether it is driven by improvements within the individual, by selective
mortality of poor performers, or both.
Here we exploit the opportunity
offered by long-term monitoring of individuals through Global
Positioning System (GPS) satellite tracking to combine within-individual
and cross-sectional data on 364 migration episodes from 92 individuals
of a raptorial bird, aged 1–27 years old. We show that the development
of migratory behaviour follows a consistent trajectory, more gradual and
prolonged than previously appreciated, and that this is promoted by
both individual improvements and selective mortality, mainly operating
in early life and during the pre-breeding migration. Individuals of
different age used different travelling tactics and varied in their
ability to exploit tailwinds or to cope with wind drift. All individuals seemed aligned along a race with their contemporary
peers, whose outcome was largely determined by the ability to depart
early, affecting their subsequent recruitment, reproduction and
survival. Understanding how climate change and human action can affect
the migration of younger animals may be the key to managing and
forecasting the declines of many threatened migrants.
See also at IMEDEA
(CSIC-UIB) and IMEDEA Divulga
here
