Assessing vector navigation in long-distance migrating birds

Åkesson, Susanne; Bianco, Giuseppe

doi:10.1093/beheco/arv231

Cited by 22 publications

(39 citation statements)

References 61 publications

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“…In the unique case of the Northern Wheatear Oenanthe oenanthe migrating from Greenland to western Africa across the ocean, sun compass and magnetoclinic routes were the only two possible options that would generate realistic routes across the North Atlantic leading to predicted destinations in southwestern Europe and Africa (Table 1; Åkesson and Bianco 2016). We find this species of particular interest and will discuss the Northern Wheatear migration from the most eastern part of its breeding range in more detail below.…”

Section: Route Simulationsmentioning

confidence: 99%

Route simulations, compass mechanisms and long-distance migration flights in birds

Åkesson

Bianco

2017

J Comp Physiol A

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Bird migration has fascinated humans for centuries and routes crossing the globe are now starting to be revealed by advanced tracking technology. A central question is what compass mechanism, celestial or geomagnetic, is activated during these long flights. Different approaches based on the geometry of flight routes across the globe and route simulations based on predictions from compass mechanisms with or without including the effect of winds have been used to try to answer this question with varying results. A major focus has been use of orthodromic (great circle) and loxodromic (rhumbline) routes using celestial information, while geomagnetic information has been proposed for both a magnetic loxodromic route and a magnetoclinic route. Here, we review previous results and evaluate if one or several alternative compass mechanisms can explain migration routes in birds. We found that most cases could be explained by magnetoclinic routes (up to 73% of the cases), while the sun compas s could explain only 50%. Both magnetic and geographic loxodromes could explain <25% of the routes. The magnetoclinic route functioned across latitudes (1°S–74°N), while the sun compass only worked in the high Arctic (61–69°N). We discuss the results with respect to orientation challenges and availability of orientation cues.Electronic supplementary materialThe online version of this article (doi:10.1007/s00359-017-1171-y) contains supplementary material, which is available to authorized users.

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Section: Route Simulationsmentioning

confidence: 99%

Route simulations, compass mechanisms and long-distance migration flights in birds

Åkesson

Bianco

2017

J Comp Physiol A

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“…There are different more sophisticated ways for calculating flow assistance but all require additional assumptions on the degree of wind compensation in the form of changes in the bird's heading and speed, either air-or ground speed depending of the strategy considered, which would increase the complexity of the analysis [54]. Indeed, one of the approaches proposed to disentangle the differences between the different possible assumptions is to use a flow assistance individual based model to simulate the trajectories that an animal would exhibit in the real world if it acted according to the rules of a specific preferred direction of movement, that is a compass direction, combined to one of the possible flow assistance strategies ( [54], see also [78]). Future studies on swift migration should integrate observations and modelling to shed light also on compass mechanisms used in flight and to what extent swifts can deal with side winds by compensation in the numerical models of movement strategies, including the possibility to change altitude rather than speed or heading to use more profitable winds.…”

Section: (D) Migration In Relation To Windsmentioning

confidence: 99%

Negotiating an ecological barrier: crossing the Sahara in relation to winds by common swifts

Åkesson

Bianco

Hedenström

2016

Phil. Trans. R. Soc. B

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One contribution of 17 to a theme issue 'Moving in a moving medium: new perspectives on flight'. The Sahara Desert is one of the largest land-based barriers on the Earth, crossed twice each year by billions of birds on migration. Here we investigate how common swifts migrating between breeding sites in Sweden and wintering areas in sub-Saharan Africa perform the desert crossing with respect to route choice, winds, timing and speed of migration by analysing 72 geolocator tracks recording migration. The swifts cross western Sahara on a broad front in autumn, while in spring they seem to use three alternative routes across the Sahara, a western, a central and an eastern route across the Arabian Peninsula, with most birds using the western route. The swifts show slower migration and travel speeds, and make longer detours with more stops in autumn compared with spring. In spring, the stopover period in West Africa coincided with mostly favourable winds, but birds remained in the area, suggesting fuelling. The western route provided more tailwind assistance compared with the central route for our tracked swifts in spring, but not in autumn. The ultimate explanation for the evolution of a preferred western route is presumably a combination of matching rich foraging conditions (swarming insects) and favourable winds enabling fast spring migration.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'.

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“…We simulated the autumn migration of the willow warblers from the breeding area in eastern Siberia to wintering grounds in central-east Africa assuming four vector-navigation mechanisms following the approach in Åkesson and Bianco [ 3 ]. Each mechanism is based on a proposed compass used by birds for navigation that generates a predictable route as follows: (a) geographic loxodrome route, generated by a star compass [ 30 ]; (b) sun compass route, using the bird’s internal clock to predict the apparent motion of the sun and taking into account the longitudinal time-shift according to Alerstam and Pettersson [ 11 ]; (c) magnetic loxodrome route, with constant bearing relative to magnetic North; and (d) magnetoclinic route, keeping constant the apparent angle of magnetic inclination according to Kiepenheuer [ 45 ].…”

Section: Methodsmentioning

confidence: 99%

“…[ 38 , 73 ])? Second, can the evolution of migratory routes used by individual birds be explained by one or several simple compass mechanisms [ 3 ], and if so, can we expect different compass mechanisms to be used at different latitudes [ 4 ]? We may further ask if adult birds follow the same route as they did as young inexperienced migrants and if they use additional cues for goal navigation during later migrations as may be expected (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…First, we were interested to determine the route choice by this population of willow warblers, the locations of stopover and wintering sites as well as the timing of migration. Second but foremost, we used these routes that traverse ~ 140° longitudes and ~ 80° latitudes to evaluate if the migration could be explained by a gradual increase in distance of a preferred route, based on a simple compass mechanism that relies on celestial or geomagnetic information [ 3 , 4 ]. We therefore set up the following alternative hypotheses that willow warblers expanding to this easternmost part of the range would follow: 1) an autumn migratory route, explained by a single compass mechanism [ 3 ], or 2) a route, which involves directional shifts, with two (or more) distinct migratory courses differing from each other and expressed in sequence (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Ten grams and 13,000 km on the wing – route choice in willow warblers Phylloscopus trochilus yakutensis migrating from Far East Russia to East Africa

et al. 2018

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BackgroundHigh-latitude bird migration has evolved after the last glaciation, in less than 10,000–15,000 years. Migrating songbirds rely on an endogenous migratory program, encoding timing, fueling, and routes, but it is still unknown which compass mechanism they use on migration. We used geolocators to track the migration of willow warblers (Phylloscopus trochilus yakutensis) from their eastern part of the range in Russia to wintering areas in sub-Saharan Africa. Our aim was to investigate if the autumn migration route can be explained by a simple compass mechanism, based on celestial or geomagnetic information, or whether migration is undertaken as a sequence of differential migratory paths possibly involving a map sense. We compared the recorded migratory routes for our tracked birds with simulated routes obtained from different compass mechanisms.ResultsThe three tracked males were very similar in the routes they took to their final wintering sites in southern Tanzania or northern Mozambique, in their use of stopover sites and in the overall timing of migration. None of the tested compass mechanisms could explain the birds’ routes to the first stopover area in southwest Asia or to the destination in Southeast Africa without modifications. Our compass mechanism simulations suggest that the simplest scenarios congruent with the observed routes are based on either an inclination or a sun compass, assuming two sequential steps.ConclusionsThe birds may follow a magnetoclinic route coinciding closely with the tracks by first moving west, i.e. closer to the goal, and thereafter follow a constant apparent angle of inclination to the stopover site. An alternative would be to use the sun compass, but with time-adjustments along the initial part of the migration to the first stopover, and thereafter depart along a new course to the winter destination. A combination of the two mechanisms cannot be ruled out, but needs to be confirmed in future studies.Electronic supplementary materialThe online version of this article (10.1186/s40462-018-0138-0) contains supplementary material, which is available to authorized users.

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Assessing vector navigation in long-distance migrating birds

Cited by 22 publications

References 61 publications

Route simulations, compass mechanisms and long-distance migration flights in birds

Route simulations, compass mechanisms and long-distance migration flights in birds

Negotiating an ecological barrier: crossing the Sahara in relation to winds by common swifts

Ten grams and 13,000 km on the wing – route choice in willow warblers Phylloscopus trochilus yakutensis migrating from Far East Russia to East Africa

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