Hoe worden individuele trekroutes gevormd? Jonge Schreeuwarenden leren de juiste flyway van hun ouders in hun eerste levensjaar, terwijl jonge Wespendieven pas veel later de traditionele voorjaarsroutes weten. Wouter van Steelant.

1. Culturele overerving van
trekroutes bij roofvogels
Inzichten uit zenderonderzoek
aan Schreeuwarend en
Wespendief
Wouter Vansteelant
@WMGVs

2. Overland migratory detours: a common
feature in soaring bird migration
Bildstein 2000 Raptors of the World
Batumi, Georgia
> 1.000.000

4. In contrast to cranes, geese, … soaring
migrants do NOT travel in family groups

5. Nevertheless, they tune into a narrow
corridor already on the 1st migration

6. Lesser Spotted Eagle
Clanga pomarina
with Bernd Meyburg et al.

7. Lesser Spotted Eagle:
a threatened species in decline
Meyburg et al. (2008) Slovak Raptor Journal

8. Cain and Abel
Meyburg et al. (2008) Slovak Raptor Journal

9. Nestling management:
´Saving Abels´ through fostering
Meyburg et al. (2008) Slovak Raptor Journal

10. Nestling management:
´Saving Abels´ through hacking

11. Saving Abels in Brandenburg

12. Falsterbo
Gibraltar
Messina
Bosporus
Eilat
Suez
Bab-el-Mandeb
Batumi
Lesser Spotted Eagle in the European
raptor migration flyways
Burgas

13. 5,500
0-1
Lesser Spotted Eagle in the European
raptor migration flyways
1-10
1-10
82,000
15,000
50,000

14. A B C D
Overlap in adult and juvenile migration
timing

15. Saving Abels in Brandenburg

16. Orientation during the first autumn
migration

17. Orientation during the first autumn
migration
N=9

18. Orientation during the first autumn
migration
N=9
N=8

19. Orientation during the first autumn
migration
N=9
N=8
N=12

20. A: departure
B: 50N (well on
the way)
C: 40N (leaving
Europe)
D: 30N (arrival in
Africa)
Increasing overlap
between groups in
time and space

21. Route choice is associated with
migration timing: social learning!
© Amir Ben dov

22. Survival between age classes

23. Survival between age classes
and flyways

24. • Annual arrival time in Israel (0) accurately predicted (+) by precipitation in
eastern Europe.
Shamoun-Baranes et al. (2006) Global Ecology and Biogeography
Why did the juveniles from Latvia
depart before the main exodus?
• Weather conditions?

25. • Annual arrival time in Israel (0) accurately predicted (+) by precipitation in
eastern Europe.
• However: no evidence to support a weather-induced difference in
migration timing
Shamoun-Baranes et al. (2006) Global Ecology and Biogeography
• Weather conditions?
Why did the juveniles from Latvia
depart before the main exodus?

26. • Social cues?
Why did the juveniles from Latvia
depart before the main exodus?

27. • Social cues?
Why did the juveniles from Latvia
depart before the main exodus?

28. Death
Migration (1 not shown): 5
Winter 1CY (3 not shown): 7
3 died on nest before migration
Survival rate 1CY: 16/31 ~ 52%
Comparison with other
soaring migrants
Oppel et al. 2015 - Ibis

29. Death
Migration (1 not shown): 5
Winter 1CY (3 not shown): 7
3 died on nest before migration
Survival rate 1CY: 16/31 ~ 52%
Comparison with other
soaring migrants
Mellone et al. 2016 - Ibis

30. JAN-JUL AUG-DEC
Migratory development of
native survivors

31. JAN-JUL AUG-DEC
Migratory development of
native survivors

32. JAN-JUL AUG-DEC
Migratory development of
native survivors

33. JAN-JUL AUG-DEC
Migratory development of
native survivors

34. JAN-JUL AUG-DEC
Migratory development of
native survivors

35. JAN-JUL AUG-DEC
Migratory development of
native survivors
JAN-JUL

36. JAN-JUL AUG-DEC
Migratory development of
native survivors

37. JAN-JUL AUG-DEC
Migratory development of
native survivors
JAN-JUL

38. JAN-JUL AUG-DEC
Migratory development of
native survivors

39. European Honey Buzzard
Pernis apivorus
with Patrik Byholm

40. AUTUMN SPRING
Conservative migration routes in the
western flyway

41. Main results PhD research
Highly complex behaviour compared
to expectations from conventional
migration theory
• HB´s make the most of the
weather, but don´t race against
the clock
• Risk avoidance > early arrival
• Overcompensation for wind at
start of spring migration
indicates ‘anticipation’ of
favourable winds along a
westward detour

42. The adaptive nature of detours:
go with the flow and avoid excessive risk

43. Finnish satellite tracking project:
http://www.luomus.fi/en/satellite-honey-buzzards
Spring Autumn
Adult route choice much more flexible in
eastern vs. western population

44. A B C D
Age-dependent migration

45. A B C D
Age-dependent migration

46. Spring Autumn
Age-dependent migration
Adult Immature

47. Mastering migration:
ontogeny revealed by
life-long tracking
Age (CY)
Senner NR, Conklin JR, Piersma T.
Proc Biol Sci. (2015)

48. Adults leave early
and mostly catch
tailwinds along relatively
eastern corridor to their
established wintering sites
Juveniles may be drifted far
to the west, determining
longitude at which they
establish their primary
wintering site
First outbound migration
Vansteelant et al. (2017)
Proceedings Royal Society B

49. Wind and geography shape first autumn
migration and distribution across Africa
Vansteelant et al. 2017 Proc. R Soc. B.
OPEN ACCESS

50. Wind and geography shape first autumn
migration and distribution across Africa
Vansteelant et al. 2017 Proc. R Soc. B.
OPEN ACCESS

51. Wind and geography shape first autumn
migration and distribution across Africa
Vansteelant et al. 2017 Proc. R Soc. B.
OPEN ACCESS

52. Wind and geography shape first autumn
migration and distribution across Africa
Vansteelant et al. 2017 Proc. R Soc. B.
OPEN ACCESS

53. First outbound migration
Death
Migration (1 not shown): 5
Winter 1CY (3 not shown): 7
3 died on nest before migration
Survival rate 1CY: 16/31 ~ 52%
Mortality on first autumn
migration much lower
than in other species!

54. First outbound migration
Death
Migration (1 not shown): 5
Winter 1CY (3 not shown): 7
3 died on nest before migration
Survival rate 1CY: 16/31 ~ 52%

55. First outbound migration
Death
Migration (1 not shown): 5
Winter 1CY (3 not shown): 7
3 died on nest before migration
Survival rate 1CY: 16/31 ~ 52%

56. Highly variable age of first migration

57. Slow learning of traditional spring
migration routes: resulting in high mortality

58. Slow learning of traditional spring
migration routes: resulting in high mortality

59. Slow learning of traditional spring
migration routes: resulting in high mortality

60. Slow learning of traditional spring
migration routes: resulting in high mortality

61. Slow learning of traditional flyways in spring:
associated to delayed shift from juvenile to adult timing
Synchronisation with adults needed for cultural
transmission of traditional spring detours

62. Age
Age
DepartureDOYDuration
SPRING AUTUMN
Learning the flyway:
timing & social learning

63. Thanks!
Questions?