Doi: http://dx.doi.org/10.13157/arla.60.1.2012.59
Authors: Miren ANDUEZA, Juan ARIZAGA, Eduardo Jorge BELDA and Emilio BARBA
E-mail: miano2@alumni.uv.es
Published: Volume 60(1), June 2013. Pages 59-72.
Language: English
Keywords: Cormack-Jolly-Seber models, date, density, , departure decision, sedge warbler and tailwind assistance
Summary:
Factors determining departure decisions of migrants from a stopover site
can be extrinsic and/or intrinsic but the relative role of each of
these factors on departure decisions is still poorly known. Date and
wind should be the main factors determining departure decisions in a
long-distance migrant, which is expected to minimise duration of
migration. Date was considered as an intrinsic factor and wind as an
extrinsic one. We analysed the capture-recapture data of a long-distance
migrant European songbird, the sedge warbler Acrocephalus
schoenobaenus, from a stopover site in northern Iberia during the autumn
migration period to quantify the relative importance of several factors
on emigration likelihood. Cormack-Jolly-Seber (CJS) models were used to
estimate the emigration likelihood. From 107 models tested, only the
model with an additive effect of date, tailwind assistance and
population size substantially supported the data. As expected, sedge
warblers were more likely to depart with high tailwind values and late
in the season and, contrary to expectations, with decreasing sedge
warbler abundance.