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| This study aims to investigate causes and
mechanisms controlling protandrous migration patterns
(the earlier breeding area arrival of males relative to
females) and inter-sexual differences in timing of migration
in relation to the recent climate-driven changes in
phenology. Using standardised ringing data from a single
site for eight North European migratory passerines collected
throughout 22 years, we analysed sex-differentiated
migration patterns, protandry and phenology of the entire
populations. Our results show protandrous patterns for the
first as well as later arriving individuals for all studied
species. Males show more synchronous migration patterns
compared to females and, hence, first arriving females
followed males more closely than later arriving individuals.
However, we found no inter-sexual differences in arrival
trends as both sexes advance spring arrival over time with
the largest change for the first arriving individuals. These
findings seem in support of the ‘‘mate opportunity’’
hypothesis, as the arrival of males and females is strongly
coupled and both sexes seem to compete for early arrival.
Changes in timing of arrival in males and females as a
response to climatic changes may influence subsequent
mating decisions, with subsequent feedbacks on population
dynamics such as reproductive success and individual fitness.
However, during decades of consistent earlier spring
arrival in all phases of migration we found no evidence of
inter-sexual phenological differences. | |
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