Patterns and processes in shorebird survival rates: a global review

Abstract

PortugalChanges in demographic rates underpin changes in population size, and understanding demographic rates can greatly aid the design and development of strategies to maintain populations in the face of environmental changes. However, acquiring estimates of demographic parameters at relevant spatial scales is difficult. Measures of annual survival rates can be particularly challenging to obtain because large-scale, long-term tracking of individuals is difficult and the resulting data contain many inherent biases. In recent years, advances in both tracking and analytical techniques have meant that, for some taxonomic groups, sufficient numbers of survival estimates are available to allow variation within and among species to be explored. Here we review published estimates of annual adult survival rates in shorebird species across the globe, and construct models to explore the phylogenetic, geographical, seasonal and sex-based variation in survival rates. Models of 295 survival estimates from 56 species show that survival rates calculated from recoveries of dead individuals or from return rates of marked individuals are significantly lower than estimates from mark-recapture models. Survival rates also vary across flyways, largely as a consequence of differences in the genera that have been studied and the analytical methods used, with published estimates from the Americas and from smaller shorebirds (Actitis, Calidris and Charadrius spp.) tending to be underestimated. By incorporating the analytical method used to generate each estimate within a mixed model framework, we provide method-corrected species-specific and genusspecific adult annual survival estimates for 52 species of 15 genera.

A Migratory Divide Among Red-Necked Phalaropes in the Western Palearctic Reveals Contrasting Migration and Wintering Movement Strategies

“…Four CJS models had AICc values <2, including the simplest model ( AICc = 0.64), which estimated p at 0.52 (CI = 0.31-0.71) and ϕ at 0.32 (CI = 0.23-0.43). An apparent survival rate of 0.32 is notably low for a wader species (Méndez et al, 2018) but is within the range of 0.17 to 0.56 reported from sites in Alaska (Colwell et al, 1988;Schamel and Tracy, 1991;Sandercock, 1997) and likely reflects a low site fidelity rather than survival. Nevertheless, a weak effect of geolocator deployment cannot be ruled out, considering we could not compare against a control group without a geolocator, and knowing that a geolocator attached to a leg flag and weighing >2.5% of the body mass led to lower return rates in other small wader species (Weiser et al, 2016).…”

Disentangling data discrepancies with integrated population models

“…Informed priors may also originate from comparative studies, such as reviews of vital rates in closely related taxa (e.g., global reviews of survival rates in shorebirds; Méndez et al. ) or larger‐scale studies that use allometric scaling (e.g., survival vs. body mass relationships in birds and mammals; McCarthy et al. ).…”

Why study plovers? The significance of non-model organisms in avian ecology, behaviour and evolution

“…Wetlands, which account for some of the main breeding and non-breeding habitats of shorebirds, are disappearing at an alarming rate globally, and by working in the field on a day-to-day basis, we saw numerous examples of nest predation by feral cats and dogs, illegal hunting and rapid habitat loss. True, many shorebirds have flexible breeding strategies-indeed, the fluctuating nature of suitable habitats is one of the theories put forward to explain diverse breeding strategies (Oring 1986;Erckmann 1981)-nonetheless, if suitable habitats decline, this can only mean declining overall population sizes, reduced productivity and/or increased mortality (Méndez et al 2018). Shorebird species have indeed gone extinct since records began (e.g.…”

“…More recently, Kubelka et al (2018) has shown that rates of nest predation of many shorebirds have increased substantially in recent years, and that the largest increase was in the Arctic. The effects on Arctic shorebirds, many of which are long-distance migrants, are twofold: nest mortality is increasing, and adult survival is decreasing (Méndez et al 2018). These pressures are, unfortunately, likely to feed into declining shorebird populations worldwide, and especially in the Arctic (Kubelka et al 2018).…”