Data from: Individual shifts toward safety explain age-related foraging distribution in a gregarious shorebird ...

• Main Authors: Van Den Hout, Piet J., Piersma, Theunis, Ten Horn, Job, Spaans, Bernard, Lok, Tamar
• Format: Dataset
• Language: English
• Published: Dryad 2016
• Subjects: Safety; foraging proficiency; age; Calidris canutus
• Online Access: https://dx.doi.org/10.5061/dryad.75s6t; https://datadryad.org/stash/dataset/doi:10.5061/dryad.75s6t

Although age-related spatial segregation is ubiquitous, the underlying mechanisms are poorly understood. Here, we aim to elucidate the processes behind a previously established age-related foraging distribution of red knots (Calidris canutus canutus) in their main wintering area in West Africa (Banc d’Arguin, Mauritania). Based on 10 years of observations of 1232 uniquely color-ringed individuals of 1 to 18+ years old, we examined whether the observed age-related foraging distribution resulted from 1) spatial differences in mortality or 2) age-related shifts in habitat use. Using multistate capture–recapture modeling, we showed that with age foraging red knots moved away from the shoreline, that is, to areas with fewer surprise attacks by raptors. Considering uncertainties in the subjective gradient in predation danger with increasing distance from shore (as assessed from correlations between vigilance and distance from shore in foraging birds), we applied 2 different danger zone boundaries, at 40 m and 500 ... : text filesData are provided for: Fig. 2 panels a (avgHUdfs10.txt) and b (vigilance_largescale.txt): vigilance as a function of distance from shore; Fig. 3: Number of individuals that were observed in nearshore dangerous and offshore safe habitat, shown for the 40 m (ch.knots.40m.txt ) and 500 m (ch.knots.500m.txt) danger zone boundaries; for the Multi-state mark-recapture analyses with use of the RMark package, including fig. 4(cr.knots.May2015.txt)for Dryad.7z ...