Data from: Quantifying population size of migrant birds at stopover sites: combining count data with stopover length estimated from stable isotope analysis ...

• Main Authors: Catry, Teresa, Lourenço, Pedro Miguel, Granadeiro, Jose Pedro
• Format: Dataset
• Language: English
• Published: Dryad 2018
• Subjects: Calidris alpina; shorebirds; Population size; Dunlin
• Online Access: https://dx.doi.org/10.5061/dryad.771p1; https://datadryad.org/stash/dataset/doi:10.5061/dryad.771p1

1. Regular counts of migrating animals at stopover sites have been used as a measure of site importance at the global scale as well as for monitoring long-term population changes. However, migratory passage can last for several weeks and the turnover rate of individuals is often high, preventing the use of peak counts to estimate the total number of migrants. This estimate can be achieved, however, by combining count data with information on stopover length. 2. Here, we developed a new method to quantify the total number of migrant birds using stopover areas hosting overlapping populations of local (breeding, wintering or resident) and passage individuals of a given species. We illustrate the application of this method by estimating the number of spring migrant dunlins Calidris alpina stopping over at the Tagus estuary (Portugal). We used carbon and nitrogen isotopic signatures in toenails to identify migrants and to estimate their proportion in total counts. We then employed isotopic clock-models to ... : Dunlin (Calidris alpina) countsTotal number of dunlins (Calidris alpina) counted in high-tide roost regular counts at the Tagus estuary (Portugal) during spring migration.contagens.xlsCarbon and nitrogen stable isotopic ratios of Dunlin (Calidris alpina)Carbon and nitrogen stable isotopic signatures of dunlin (Calidris alpina) toenails, red blood cells (RBC) and plasma collected at the Tagus estuary (Portugal) and Banc d'Arguin (Mauritania) during the winters of 2012-2013 and 2013-2014, and at the Tagus estuary (Portugal) during spring migration of 2013 and 2014. Wintering origins of dunlins sampled during spring migration at the Tagus estuary, as determined by a discriminant analysis based on isotopic signatures of toenails (see Catry et al. 2016, 10.1016/j.baae.2015.10.005), are also included. Birds identified as originating from wintering areas outside Mauritania and Portugal (e.g. Morocco) are included in the dataset but were excluded from further analyses, as well as two birds with low classification ...