DOI: 10.5061/dryad.kd00f
title: Data from: Simultaneous declines in summer survival of three shorebird species signals a flyway at risk

description: 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.
description: Individual encounter
 histories of bar-tailed godwits, great knots and red knots during 3
 seasonsThe datafile contains
 the encounter histories of 821 bar-tailed godwits (Limosa lapponica
 menzbieri), 1064 great knots (Calidris tenuirostris) and 709 red knots
 (Calidris canutus, primarily of the subspecies piersmai) that were
 individually marked and resighted at their primary non-breeding area
 Roebuck Bay (North-West Australia) between December 2005 and June 2013.
 All birds were caught using cannon-netting, individually marked with 4
 coloured bands and a flag and instantly released. Resightings occurred
 throughout the non-breeding season. To allow the estimation of survival
 during three seasons of the year, the captures and resightings were pooled
 into three periods: Jul-Oct, Nov-Feb, Mar-Jun. The median dates of
 resightings during these three periods, rounded to the 1st of the month,
 were 1 Oct, 1 Jan and 1 Apr, hence the intervals over which survival rates
 were estimated were approximately 3, 3 and 6 months. The encounter
 histories start with the period in which the individual was captured and
 individually marked. Each row in the datafile represents one individual,
 and the three columns represent the encounter history (ch), where
 individuals are either seen (1) or not seen (0) during a particular
 period, the age of the bird when it was first captured and individually
 marked (age_at_ringing), distinguishing first-year (1) and older (2)
 birds, and the species (species), where BTG=bar-tailed godwit, GK=great
 knot and RK=red knot.Encounter_history_data_3_seasons_3_species.txtIndividual encounter histories of red knots during 4 seasonsThe datafile contains the encounter histories of 348 individually marked adult red knots (Calidris canutus, primarily of the subspecies piersmai) that were resighted at their primary non-breeding area Roebuck Bay and during spring stopover, in Bohai Bay (China) between May 2009 and April 2013. All birds were caught in Roebuck Bay using cannon-netting, individually marked with 4 coloured bands and a flag and instantly released. To estimate survival during four seasons, the resightings were pooled into four periods: Jul-Oct, Nov-Feb and Mar-Apr in Roebuck Bay and April-June in Bohai Bay (China). The median dates of resightings during these four periods, rounded to the 1st of the month, were 1 Oct, 1 Jan, 1 Apr and 15 May, hence the intervals over which survival rates were estimated were approximately 3, 3, 1.5 and 4.5 months. The encounter histories start with the first sighting of an individual at spring stopover in Bohai Bay. In subsequent resighting periods, the individual can either be seen (1) or not seen (0).Encounter_history_data_4_seasons_red_knots.txt