1. Spatiotemporal organization of
songbird migration covering
30,000 km
Heiko Schmaljohann, James W. Fox & Franz Bairlein
Institute of Avian Research
„Vogelwarte Helgoland“

2. Introduction
movement ecology
• quantify migration in a high spatiotemporal resolution
Nathan et al. 2008 PNAS
elements of migration
• flight route, flight direction, stopover duration, flight
speed, fuel deposition rate
optimal migration theory Alerstam & Lindström 1990 Phys & Ecophys
• predicts by assuming time minimization as the overall
strategy that the bird’s fuel load is a function of stopover
duration, fuel deposition rate, flight routes and flight
speed
Lindström & Alerstam 1992 Am Nat, Hedenström & Alerstam 1995 Phil Trans R Soc B,
Alerstam 2001 Science, Hedenström 2008 Phil Trans R Soc B

3. Introduction
studies
• in large birds by satellite tracking (geese, raptors)
Mandel et al. 2008 PNAS, Klaassen et al. 2010 Proc R Soc B
• but not in small birds: due to weights of tracking devices
studies have been focused on single flight legs / stopover
sites
Lindström and Alerstam 1992 Am Nat, Wikelski et al. 2003 Nature,
Schmaljohann & Naef-Daenzer 2011 J Anim Ecol
light-level geolocator
„Light-level geolocation is the calculation of position from
ambient light level readings with reference to time.“ BAS
• development of light-level geolocators has set ecologists
in a euphoric mood
Shaffer et al. 2008 PNAS, Robinson et al. 2009 TREE, Stutchbury et al. 2009 Science,
Bächler et al. 2010 PLoSONE, Conklin et al. 2010 Nat Comm, Egevang et al. 2010 PNAS

4. Introduction
light-level geolocator
• advantage
- small and „cheap“
• disadvantage
- sample size depends on recapture probability
- equinoxes (is the date when the day length is the same
throughout all latitudes)
„2-3 weeks around each equinox the calculation of
latitude is unreliable or impossible!“ BAS
this is the main migration period of many bird
species!
Stutchbury et al. 2009 Science, Bächler et al. 2010 PLoSONE

5. Introduction
Purple Martin
(Progne subis)
Wood Thrush
(Hylocichla
mustelina)
Stutchbury et al. 2009 Science

6. Introduction
Longitude is unaffected by
equinox.
Bächler et al. 2010 PLoSONE

7. Introduction
northern wheatear (Oenanthe oenanthe)
- insectivorous songbird (~ 30 g)
- nearly circumpolar breeding distribution
- prefers open habitats (tundra, savannah)
- all over-winter south of the Sahara

8. Aim of study
to quantify migration in a high spatiotemporal resolution
allows a detailed description of northern wheatear’s
migration strategy
- flight route
- organization of stopover
- flight speeds
- temporal distribution of life history stages within
an annual cycle

9. Methods
Alaska
June 2009: 30 birds with geolocators
June 2010: 5 returned, gained 3 geolocators

10. Methods
Precalibration
Helgoland, Germany (54° 11’ N, 07° 55’ E)
20th May - 27th of May 2009
Accuracy of single fixes to the reference site during
precalibration was limited to 76 ± 33 km (nnumber of fixes = 39).
longitudinal deviation: 45.6 ± 35.0 km
latitudinal deviation: 47.1 ± 37.6 km
(nnumber of fixes = 39)

11. Methods

12. Methods
160° W ● midnight fix
● noon fix
160° E
120° E
6
80° E 8
6
40° E
1.4.
15.4.
1.5.
15.5
Spring 2010

13. Methods
Defining stopover sites
> 2 noon fixes within 1° of longitude
Dierschke & Delingat 2001 Behav Ecol Sociobiol, Schmaljohann & Dierschke 2005 J Anim Ecol
Dierschke, Mendel & Schmaljohann 2005 Behav Ecol Sociobiol, Schmaljohann et al. 2011 J Ornithol,
Schmaljohann & Naef-Daenzer 2011 J Anim Ecol

14. Methods
160° W ● midnight fix
● noon fix
160° E
120° E
6
80° E 8
6
6
40° E
1.4.
15.4.
1.5.
15.5
Spring 2010

15. Methods
160° W 5 ● midnight fix
● noon fix
5
160° E
120° E
4
80° E 5
4
10 18 9
8
40° E
15.10.
15.11.
15.8.
1.9.
15.9.
1.10.
1.11.
1.12.
Autumn 2009

16. Methods

17. Methods
raw data, NO outliners

18. Methods
Local Polynomial Regression Fitting;
loess(latitude ~ longitude, data excluding „outliners“)

19. Methods
raw data, 7 outliners not shown

20. Methods

21. Methods
Estimating „uncertainty“ of migration route
raw fix
●
distance of raw fix to
smoothed migration route
smoothed migration route

22. Methods
106 ± 107 km, n = 15
220 ± 212 km, n = 37

23. Results – migration strategy
A
D
mean ± SD distance of
fixes from smoothed lines
A: 156 ± 153 km, n = 14
B
B: 276 ± 155 km, n = 7
C: 719 ± 577 km, n = 18
C
D: 99 ± 59 km, n = 15

24. Results – migration strategy
Onset of autumn migration 17 Aug, 20 Aug, 20 Aug 2009
Distance between stopover
prior to Arabian desert ~ 280 ± 115 km
Arrival in eastern Africa 11 Nov, 13 Nov, 14 Nov 2009
Distance of autumn migration 14.800 km, 14.900 km, 15.300 km
Ø migration speed autumn ~160 km·day-1 [370 km·night-1]
Distance between wintering
areas ~ 400 ± 180 km
Onset of spring migration 8 Apr, 30 Mar, 28 Mar 2010
Arrival at breeding area -, 23 May, 24 May 2010
Distance of spring migration -, 14.100 km, 14.250 km
Ø migration speed spring ~260 km·day-1 [400 - 500 km·night-1]

25. Results – migration strategy
search and settling time/cost
to establish feeding territories and to adapt physiologically to
replenish their energy expenditure from the previous flight
Alerstam & Lindström 1990 Phys & Ecophys, Alerstam & Hedenström 1998 J Avian Biol, Jenni &
Schaub 2003 Bird Migration
this search and settling time is an important hypothesis
influencing the predicted fuel load, stopover duration and number of
flights during the entire migration
Alerstam & Lindström 1990 Phys & Ecophys
only little evidence for a natural search and settling time
Schwilch & Jenni 2001 Auk, Delingat et al. 2006 Ardea
“stop-and-go” migration strategy for Alaskan northern wheatears
This diminishes the biological importance of a search
and settling time at least for northern wheatears.

26. Results – migration strategy
overall migratory speed
“two” times higher in spring than in autumn indicating a higher
time pressure to reach the migratory goal
Hall-Karlsson & Fransson 2008 Ring & Mig, Stutchbury et al. 2009 Science, Bächler et al. 2010
PLoSONE
as northern wheatears migrate only at night, also when crossing
ecological land barriers, the nocturnal flight speed ranged here
between 300 and 500 km·night-1
Schmaljohann et al. 2007 Proc R Soc B, Schmaljohann & Naef-Daenzer 2011 J Anim Ecol
These nocturnal flight speeds are far higher than formerly
predicted.

27. Results – migration strategy
breeding
spatiotemporal organization
~ 70 days
+ complete moult
spring ~ 50 days
migration breeding area
~ 55 days ~ 80 days autumn
migration
~ 88 days
wintering area
~ 140 days
To maximize the flexibility in timing of the
life history stages northern wheatears
overlap breeding and moult.
McNamara & Houston 2008 Phil Trans R Soc B, Wingfield 2008 Phil Trans R Soc B

28. take-home massages
optimal migration theory
search and settling time seems to be low
flight speed of songbirds: up to 500 km per night
overlap of life history stages (breeding and moult) to
maximize the flexibility in timing of these

29. Thank you for your attention!
Thanks to
Marc Bulte, Ommo Hüppop,
Rolf Nagel, Freimut Schramm Kevin Winker
Beth Pattinson
Robert Gill
Ellen Paul
Susan Sharbaugh
Beat Neaf-Daenzer Rachel Muheim