The average temporal distribution of primary molt in free-living adult and second-year red knots, and captive adult red knots (sexes combined, grey blocks).

<p>The dashed vertical grey lines indicate when the knots had completed growth of primary 5. Also plotted are the estimated weekly maintenance costs for a red knot living in the Wadden Sea, calculated using the model of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053890#pone.0053890-Wiersma1" target="_blank">[63]</a> (equation 5; using mudflat conductances) from daily wind, ambient temperature and solar radiation data obtained over the same period as the molt data (1998–2006; data from the Royal Netherlands Meteorological Institute (KNMI) weather station at Hoorn on the island Terschelling in the Dutch Wadden Sea, 52°23′N 5°21′E). Note that basal and thermoregulatory costs are included in maintenance costs, but molt costs (feather synthesis and increased thermoregulation) are not. Maintenance costs are indicated with circles; open circles indicate the period during which adult red knots are migrating or in the breeding areas <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053890#pone.0053890-Wiersma1" target="_blank">[63]</a>. In addition, daylength in the Wadden Sea is given (solid line, right Y-axis, data from KNMI, 2006). Arrows indicate the start of the rapid increase in number of peregrines in the Wadden Sea (P; <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053890#pone.0053890-vandenHout2" target="_blank">[54]</a>), and when the diet of free-living knots changes from shellfish to less profitable mudsnails (D; <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053890#pone.0053890-Piersma6" target="_blank">[56]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053890#pone.0053890-vanGils1" target="_blank">[58]</a>).</p

Primary molt start and end date (A, B), and molt duration (C), in free-living and captive red knots.

<p>Symbols: closed symbols, males; open symbols, females. Group abbreviations: SYM, second-year males; SYF, second-year females; FAdM, free-living adult males; FAdF, free-living adult females; CAdM, captive adult males; CAdF, captive adult females.</p