Seasonal survival and reversible state effects in a long-distance migratory shorebird

1. Events during one stage of the annual cycle can reversibly affect an
individual’s condition and performance not only within that stage, but
also in subsequent stages (i.e., reversible state effects). Despite strong
conceptual links, however, few studies have been able to empirically link
individual-level reversible state effects with larger-scale demographic
processes. 2. We studied both survival and potential reversible state
effects in a long-distance migratory shorebird, the Hudsonian Godwit
(Limosa haemastica). Specifically, we estimated period-specific survival
probabilities across the annual cycle and examined the extent to which an
individual’s body condition, foraging success, and habitat quality during
the nonbreeding season affected its subsequent survival and reproductive
performance. 3. Godwit survival rates were high throughout the annual
cycle, but lowest during the breeding season, only slightly higher during
southbound migration, and highest during the stationary nonbreeding
season. Our results indicate that overwintering godwits foraging in
high-quality habitats had comparably better nutritional status and
pre-migratory body condition, which in turn improved their return rates
and the likelihood that their nests and chicks survived during the
subsequent breeding season. 4. Reversible state effects thus appeared to
link events between nonbreeding and breeding seasons via an individual’s
condition, in turn affecting their survival and subsequent reproductive
performance. Our study thus provides one of the few empirical
demonstrations of theoretical predictions that reversible state effects
have the potential to influence population dynamics.