Wintering energetic balance and migration costs for

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Wintering energetic balance and migration costs for Icelandic Whimbrels. Camilo Carneiro1,2, Tómas G Gunnarsson2, José A Alves1,2. 1Dep. Biology ...
Wintering energetic balance and migration costs for Icelandic Whimbrels Camilo Carneiro1,2, Tómas G Gunnarsson2, José A Alves1,2 1Dep.

Biology & CESAM, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; 2South Iceland Research Centre, University of Iceland, Lindarbraut 4, IS-840 Laugarvatn, Iceland

Most waders winter in temperate and tropical regions

Weather, quality and quantity of food resources can differ considerably at each site

Variation in energetic balance

may influence

SPRING MIGRATION

• Many Icelandic Whimbrels spend the winter in West Africa but some winter further north in temperate areas • In spring,

individuals undertake either a direct flight to Iceland or make one stopover

• Each migratory strategy and migration

length likely requires different amounts of energy

How much time spent foraging at each site… 4:37h/tidal cycle 5:09h/tidal cycle 4:54h/tidal cycle

…and what net energetic intake rate? Assuming 2 tidal cycles

Iceland

During one tidal cycle Whimbrels forage for a similar period at each wintering site, but the NEIR* is different, decreasing from the tropical to the temperate area

Assuming 1 tidal cycle

*NEIR – Net Energetic Intake Rate

What is the energetic balance? χ2(2) = 905.29, p < 0.0001

Ireland Local weather conditions (wind speed, temperature and solar radiation) result in different energetic costs at each wintering site

Given the intake achieved and the costs of thermoregulation, individuals spending the winter in the Bijagós can experience the highest energetic surplus, followed by the Banc d’Arguin and Tejo

What are the energetic costs of spring migration? Tejo

In the Bijagós, Whimbrels never expect daily maintenance metabolism in excess of BMR*, whereas in the Banc d’Arguin and Tejo, the maintenance metabolism exceeds BMR in 20.6% and 7.1% of the days during the winter period

5854 km

stopover

stopover

direct

Males

direct

Maximum stored energy possible

Females

Flight models predict that Whimbrels are able to carry enough fuel to totally cover travel costs Given the migratory costs and energetic balance, Whimbrels likely require less time to store energy for migration in the Bijagós, than in Banc d’Arguin and Tejo

Banc d’Arguin

Take-Home message Although wintering in the Bijagós entails higher migratory costs, it allows Whimbrels to achieve a higher energetic balance and potentially accumulate fuel for migration in a shorter period, despite flying longer distances

Bijagós

*BMR – Basal Metabolic Rate

Icelandic Whimbrel Numenius phaeopus islandicus

Acknowledgements This work was funded by RANNIS (grants: 130412-052 and 152470-052), the University of Iceland Research Fund, FCT (grants: PD/BD/113534/2015 and SFRH/BPD/91527/2012), 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. We are grateful to Paulo Catry, Instituto da Biodiversidade e Áreas Protegidas da Guiné-Bissau, the NIOZ team and Graham Appleton.