Summary
This paper deals with the flight speeds of migrating birds observed by radar over a Swiss Alpine pass. The distributions of air speeds for different classes of birds and the influence of the wind on air speeds were investigated. Our findings differ greatly from observations of bird migration over the North Atlantic Ocean and the North American continent. Our data reveal: (1) that the air speeds of the bulk of migrating birds were in the range of 8–18 m/s and that the amount of ‘slow’ flyers (air speed below 5 m/s) was less than 5%; (2) that there was an obvious influence of the wind on air speeds and, moreover, the data showed a distinctly variable compensatory behavior among different bird classes; (3) that the wind component in the direction of the bird's heading was a better predictor for air speed than the wind direction. Although we do not speculate about possibilities and mechanisms of wind detection, a simple argument shows how birds could estimate wind directions if they do use the moving surface as a reference system.
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References
Alerstam T, Pettersson SG (1976) Do birds use waves for orientation when migrating across the sea? Nature 259:205–207
Block R, Bruderer B, Steiner P (1981) Flugverhalten nächtlich ziehender Vögel. Radardaten über den Zug verschiedener Vogeltypen auf einem Alpenpass. Vogelwarte 33:119–149
Bretschneider CL (1965) Generation of waves by wind. State of the art. NESCO Report SN-134-6. National Engineering Science Company, Washington, DC
Bruderer B (1971) Radarbeobachtungen über den Frühlingszug im Schweizerischen Mittelland. (Ein Beitrag zum Problem der Witterungsabhängigkeit des Vogelzuges). Ornithol Beob 68:89–158
Bruderer B (1978) Vogelzug. Bericht 1978 der Schweizerischen Vogelwarte, Sempach
Bruderer B (in press) Do migrating birds fly along straight lines? Int Symp on Avian Navigation, Tirrenia (Pisa), September 11–14, 1981
Bruderer B, Joss J (1969) Methoden und Probleme der Bestimmung von Radarquerschnitten frei fliegender Vögel. Rev Suisse Zool 79:1190–1200
Emlen ST (1974) Problems in identifying bird species by radar signature analysis: intra-specific variability. In: Gauthreaux (ed) Proc Conf Biological Aspects of the Bird-Aircraft Collision Problem, Clemson University, pp 509–524
Griffin DR (1972) Nocturnal bird migration in opaque clouds. In: Animal orientation and navigation. NASA SP-262, Washington, DC, pp 169–188
Griffin DR (1973) Oriented bird migration in or between opaque cloud layers. Proc Am Philos Soc 117:117–141
Larkin RP, Griffin DG, Torre-Bueno JR, Teal J (1979) Radar observation of bird migration over the western North Atlantic Ocean. Behav Ecol Sociobiol 4:225–264
Larkin RP (1980) Transoceanic bird migration: evidence for detection of wind direction. Behav Ecol Sociobiol 6:229–232
Larkin RP, Thompson D (1980) Flight speeds of birds observed with radar: evidence for two phases of migratory flight. Behav Ecol Sociobiol 7:301–317
Pennycuick CJ (1972) Animal flight. Arnold, London (Studies in biology, no. 33)
Williams TC, Williams JM, Ireland LC, Teal JM (1977) Autumnal bird migration over the western North Atlantic Ocean. Am Birds 31:251–267
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Bloch, R., Bruderer, B. The air speed of migrating birds and its relationship to the wind. Behav Ecol Sociobiol 11, 19–24 (1982). https://doi.org/10.1007/BF00297661
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DOI: https://doi.org/10.1007/BF00297661