Faster migration in autumn than in spring: seasonal migration patterns and non-breeding distribution of Icelandic whimbrels Numenius phaeopus islandicus

Camilo Carneiro*, Tómas G. Gunnarsson, José A. Alves

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

Migration is fundamental in the life of many birds and entails significant energetic and time investments. Given the importance of arrival time in the breeding area and the relatively short period available to reproduce (particularly at high latitudes), it is expected that birds reduce spring migration duration to a greater extent than autumn migration, assuming that pressure to arrive into the wintering area might be relaxed. This has previously been shown for several avian groups, but recent evidence from four tracked Icelandic whimbrels Numenius phaeopus islandicus, a long distance migratory wader, suggests that this subspecies tends to migrate faster in autumn than in spring. Here, we 1) investigate differences in seasonal migration duration, migration speed and ground speed of whimbrels using 56 migrations from 19 individuals tracked with geolocators and 2) map the migration routes, wintering and stopover areas for this population. Tracking methods only provide temporal information on the migration period between departure and arrival. However, migration starts with the fuelling that takes place ahead of departure. Here we estimate the period of first fuelling using published fuel deposition rates and thus explore migration speed using tracking data. We found that migration duration was shorter in autumn than in spring. Migration speed was higher in autumn, with all individuals undertaking a direct flight to the wintering areas, while in spring most made a stopover. Wind patterns could drive whimbrels to stop in spring, but be more favourable during autumn migration and allow a direct flight. Additionally, the stopover might allow the appraisal of weather conditions closer to the breeding areas and/or improve body condition in order to arrive at the breeding sites with reserves.

Original languageEnglish
Article numbere01938
JournalJournal of Avian Biology
Volume50
Issue number1
DOIs
Publication statusPublished - Jan 2019

Bibliographical note

Funding Information:
Acknowledgements – We are extremely thankful to Åke Lindström for discussions about estimating the first fuelling period of migration and for very constructive comments and suggestions that considerably improved this manuscript. We are grateful to all the colleagues that helped in the field, especially Verónica Méndez and Borgný Katrínardóttir, and Maria P. Dias for support with the analysis. We thank those attending our group meetings, and the several discussions with other colleagues, whose inputs are valuable; Kristinn Jónsson, for kindly allowing us to work on his land and the logistic support of the staff at the Icelandic Soil Conservation Service. Finally, we thank Nils Warnock, Phil Battley, Meijuan Zhao and Josh Nightingale for comments on previous versions of the manuscript. Funding – This work was funded by RANNIS (grants: 130412-052 and 152470-052), the Univ. of Iceland Research Fund, FCT (grants: PD/BD/113534/2015 and SFRH/BPD/91527/2012), the Portuguese Polar Program and CESAM (UID/AMB/50017 - POCI-01-0145-FEDER-007638), FCT/MCTES through national funds (PIDDAC), with co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020.

Publisher Copyright:
© 2018 The Authors

Other keywords

  • geolocator
  • migration duration
  • migration speed

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