Data from: Simultaneous declines in summer survival of three shorebird species signals a flyway at risk

There is increasing concern about the world's animal migrations. With
many land-use and climatological changes occurring simultaneously, pinning
down the causes of large-scale conservation problems requires
sophisticated and data-intensive approaches. Declining shorebird numbers
along the East Asian–Australasian Flyway, in combination with data on
habitat loss along the Yellow Sea (where these birds refuel during
long-distance migrations), indicate a flyway under threat. If habitat loss
at staging areas indeed leads to flyway-wide bird losses, we would predict
that: (i) decreases in survival only occur during the season that birds
use the Yellow Sea, and (ii) decreases in survival occur in migrants that
share a reliance on the vanishing intertidal flats along the Yellow Sea,
even if ecologically distinct and using different breeding grounds.
Monitored from 2006–2013, we analysed seasonal apparent survival patterns
of three shorebird species with non-overlapping Arctic breeding areas and
considerable differences in foraging ecology, but a shared use of both
north-west Australian non-breeding grounds and the Yellow Sea coasts to
refuel during northward and southward migrations (red knot Calidris
canutus piersmai, great knot Calidris tenuirostris, bar-tailed godwit
Limosa lapponica menzbieri). Distinguishing two three-month non-breeding
periods and a six-month migration and breeding period, and analysing
survival of the three species and the three seasons in a single model, we
statistically evaluated differences at both the species and season levels.
Whereas apparent survival remained high in north-west Australia, during
the time away from the non-breeding grounds survival in all three species
began to decline in 2011, having lost 20 percentage points by 2012. By
2012 annual apparent survival had become as low as 0.71 in bar-tailed
godwits, 0.68 in great knots and 0.67 in red knots. In a separate analysis
for red knots, no mortality occurred during the migration from Australia
to China. In the summers of low summer survival, weather conditions were
benign in the Arctic breeding areas. We argue that rapid seashore habitat
loss in the Yellow Sea is the most likely explanation of reduced summer
survival, with dire (but uncertain) forecasts for the future of these
flyway populations. This interpretation is consistent with recent findings
of declining shorebird numbers at seemingly intact southern non-breeding
sites. Policy implications. Due to established economic interests,
governments are usually reluctant to act for conservation, unless
unambiguous evidence for particular cause–effect chains is apparent. This
study adds to an increasing body of evidence that habitat loss along the
Yellow Sea shores explains the widespread declines in shorebird numbers
along the East Asian–Australasian Flyway and threatens the long-term
prospects of several long-distance migrating species. To halt further
losses, the clearance of coastal intertidal habitat must stop now.