Migration distance affects how closely Eurasian wigeons follow spring phenology during migration

• Background: The timing of migration for herbivorous migratory birds is thought to coincide with spring phenologyas emerging vegetation supplies them with the resources to fuel migration, and, in species with a capital breedingstrategy also provides individuals with energy for use on the breeding grounds. Individuals with very long migrationdistances might however have to trade of between utilising optimal conditions en route and reaching the breeding grounds early, potentially leading to them overtaking spring on the way. Here, we investigate whether migrationdistance afects how closely individually tracked Eurasian wigeons follow spring phenology during spring migration.Methods: We captured wigeons in the Netherlands and Lithuania and tracked them throughout spring migration toidentify staging sites and timing of arrival. Using temperature-derived indicators of spring phenology, we investigatedhow maximum longitude reached and migration distance afected how closely wigeons followed spring. We furtherestimated the impact of tagging on wigeon migration by comparing spring migratory timing between tracked individuals and ring recovery data sets.Results: Wigeons migrated to locations between 300 and 4000 km from the capture site, and migrated up to1000 km in a single day. We found that wigeons migrating to more north-easterly locations followed spring phenology more closely, and increasingly so the greater distance they had covered during migration. Yet we also found thatdespite tags equalling only around 2% of individual’s body mass, individuals were on average 11–12 days slower thanring-marked individuals from the same general population.Discussion: Overall, our results suggest that migratory strategy can vary dependent on migration distance withinspecies, and even within the same migratory corridor. Individual decisions thus depend not only on environmentalcues, but potentially also trade-ofs made during later life-history stages.

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

Nyckelord

Ecology

Ekologi

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