This study uses geolocators to track the seasonal migration patterns of red-backed shrikes. It finds: 1) Red-backed shrikes follow a loop migration across the Arabian Peninsula each year, covering over 22,000 km total. 2) Migration strategies differ between seasons, with spring migration faster and involving fewer stopovers than autumn migration. Autumn migration includes a long 2-month stopover in the Sahel region. 3) Timing of migration is synchronized between individuals, with early departures from breeding grounds also being early arrivals in spring.

1. Different spatio-temporal migration strategies for autumn and spring migration in a long-distance migratory songbird Anders P. Tøttrup1, Raymond Klaassen2, Roine Strandberg2, Thomas Alerstam2, Mikkel Willemoes Kristensen3, Carsten Rahbek1 and Kasper Thorup31 Centerfor Macroecology, Evolution and Climate, Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark, aptottrup@bio.ku.dk, 2 Department of Animal Ecology, Lund University, Ecology Building, SE-22362 Lund, Sweden, 3 Center for Macroecology, Evolution and Climate. Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, DenmarkEOU 2011, Riga

2. Introduction Migratory songbirds spend most of the year (8-10 months) away from breeding grounds Current knowledge about this part of their annual cycle based on ring-recoveries, stable isotopes and genetic markers. Still poorly known: How do they find there way? When and where do they migrate? How did the migration system evolve? What we need is detailed knowledge on migration routes, staging and wintering areas!

3. Introduction Songbirds follow their endogenous migration programme (Gwinner &Wiltschko 1978) - With some degree of plasticity (Biebech 1985) Optimal breeding area arrival crucial (Both et al. 2006) - Some en route adjustment (Ahola et al. 2004) They move with regular stops for refuelling (Alerstam 1990) - Expect across barriers like the Sahara where they move faster (Biebech 1985) Now, light-level loggers (geolocators) opens window of opportunity for revisiting these aspects in free-flying birds.

4. Red-backed shrikes (Laniuscollurio) A 30g, long-distance trans-Saharan migrant Loop migration across Arabian Peninsula (e.g. Zink 1985) Spring migration faster than autumn (e.g. Yohannes 2009)

6. 13 returned in 2010

7. 9 with data

8. Mk10-s, 1.0 g ; 0.8 mm stalk (from BAS)

9. Leg-loop harness

11. Departure: 14 August 9 days, 2300 km Arrival: 23 August 15 days

12. 9 days, 2300 km 15 days 7 days, 3700 km 53 days Departure: 7 September Arrival: 14 September

13. 9 days, 2300 km 15 days 7 days, 3700 km 53 days 11 days, 3700 km 129 days Departure: 8 November Arrival: 20 November

14. 9 days, 2300 km 15 days 7 days, 3700 km 53 days 11 days, 3700 km 129 days Arrival: 19 April 20 days, 3000 km 8 days Departure: 29 March

15. Arrival: 26 May 9 days, 2300 km 15 days 7 days, 3700 km 53 days 11 days, 3700 km Departure: 27 April 129 days 20 days, 3000 km 8 days 32 days, 8700 km 75 days

17. Total migration distance of 22,000 km (loop 1,000 km longer)

18. Narrow fronted spring migration - broader in autumn

19. Long Sahelian stop-over in autumn

20. Only 1 short stop-over in springTøttrup et al. in press, Proc Roy Soc B

22. But total speed highest in spring

23. Autumn speeds of 550 km/day - indicate movement every night even extending flight into daytime hours

24. Fast across Africa and EuropeTøttrup et al. in press, Proc Roy Soc B

26. No total speed difference

27. But males faster between stop-over sites compared to females

29. Does non-breeding area conditions affect spring breeding arrival time? (Spring 2010 arrival day against NDVI in the non-breeding area) NS Spearman rank: r = -0.696 N = 6, P = 0.1248

30. Some conclusions Different seasonal strategies - suggests that spring and autumn strategies evolved independently - fewer stops in spring indicate selection for time minimisation 2 month stop-over in Sahel - qualifies as third resident period Loop migration confirmed - caused by habitat or wind or a combination? Temporal synchrony between individuals - timing characterized by the individual journeys but repeated journeys needed to distinguish from environmental effects

32. All photos by Per Ekberg Petersen

33. British Antarctic Survey & Migrate Technology

34. DOF BirdLife-Denmark

35. Danish National Research Foundation