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.