Flight paths of more than 40,000 nocturnal migrants were collected by tracking radars simultaneously at two sites in spring and autumn. Winds were similar in autumn and spring: i.e., typical, rather weak trade winds with northerly directions below about 1500 m above sea level and with southerly or westerly directions higher up. The tracks of the birds were concentrated around 190° (between S and SSW) in autumn and around 5° (nearly N) in spring. Slight differences between the directional distribution of birds above the Negev Highlands and the Arava Valley could be attributed mainly to local winds and topography. Reversed migration occurring in autumn was at the altitudes of the southwesterly winds. Tracks and headings of different wingbeat classes did not differ significantly, except that birds with low wingbeat frequency and passerine-type flight had more westerly directions in autumn and more easterly directions in spring. Mean groundspeed in autumn was nearly 50 km/h, most birds profiting from following winds. In spring many migrants had to fly against the wind, thus, the groundspeed was on average lower (45 km/h) and its variation much wider than in autumn. Mean airspeed, however, was slightly higher in spring than in autumn, indicating a tendency to compensate for opposing winds. In weak winds airspeeds of wader-type birds were slightly higher than those of passerines; surprisingly, small wader-and passerine-type birds with higher wingbeat frequencies were faster than those with slower wingbeats. A high proportion of nocturnal migrants belonged to the wingbeat class of passerine-type birds. In autumn, the proportion of passerines with fast wingbeats increased from about one third in August to almost 50% at the end of October. During August and September, about one third of the identified birds had a wader-type wingbeat pattern. In spring, the proportion of passerines decreased slightly from March till May, correspondingly the proportion of wader-type birds slightly increased.
Purchase
Buy instant access (PDF download and unlimited online access):
Institutional Login
Log in with Open Athens, Shibboleth, or your institutional credentials
Personal login
Log in with your brill.com account
Adams D.W.H.Radar observations of bird migration in Cyprus Ibis 1962 104 133 146
Alerstam T.Nocturnal migration of Thrushes (Turdus sp.) in southern Sweden Oikos 1976 27 457 475
Alfiya H.Nocturnal migration of birds over Israel—changes in direction and rate of migration according to the time of night. In: Proc. Bird Strike Committee Europe 20, Helsinki 1990
Batschelet E.Circular statistics in biology Academic Press London 1981
Baumgartner M., Bruderer B.Radarbeobachtungen über die Richtungen des nächtlichen Vogelzuges am nördlichen Alpenrand Ornithol. Beob 1985 82 207 230
Biebach H., Friedrich W., Heine G., Jenni L., Jenni-Eiermann S., Schmid D.The daily pattern of autumn bird migration in the northern Sahara Ibis 1991 133 414 422
Bloch R., Bruderer B., Steiner P.Flugverhalten nächtlich ziehender Vögel—Radardaten über den Zug verschiedener Vogeltypen auf einem Alpenpass Vogelwarte 1981 31 119 149
Bruderer B.Zur Registrierung und Interpretation von Echosignaturen an einem 3-cm—Zielverfolgungsradar Ornithol. Beob 1969 66 70 87
Bruderer B.Radarbeobachtungen über den Frühlingszug im schweizerischen Mittelland Ornithol. Beob 1971 68 89 158
Bruderer B.Radar data on the orientation of migratory birds in Europe. In: Proc. 17th Int. Ornithol. Congr. Berlin 1980 547 5521978
Bruderer B.Radar studies on bird migration in the south of Israel. In: Proc. Bird Strike Committee Europe 21, Jerusalem 1992 270 280
Bruderer B.Research on bird migration by tracking radar in the Negev Torgos 1994a 23 29 38(in Hebrew, English summary)
Bruderer B.Radar studies on nocturnal bird migration in the Negev Ostrich 1994b 65 204 212
Bruderer B., Jenni L., Migration across the Alps. Bird migration: Physiology and ecophysiology Gwinner E.Springer-Verlag Berlin 1990 60 77
Bruderer B., Liechti F.Richtungsverhalten nachtziehender Vögel in Süddeutschland und der Schweiz unter besonderer Berücksichtigung des Windeinflusses Ornithol. Beob 1990 87 271 293
Bruderer B., Liechti F.Variation in density and height distribution of nocturnal migration in the south of Israel Isr. J. Zool 1995 41 477 487
Bruderer B., Underhill L., Liechti F.Altitude choice of night migrants in a desert area predicted by meteorological factors Ibis 1995a 137 44 55
Bruderer B., Steuri T., Baumgartner M.Short-range high-precision surveillance of nocturnal migration and tracking of single targets Isr. J. Zool 1995b 41 207 220
Casement M.B.Migration across the mediterranean observed by radar Ibis 1966 108 461 491
Dolnik V.R., Bird migration across arid and mountainous regions of Middle Asia and Kasakhstan. Bird migration: Physiology and ecophysiology Gwinner E.Springer-Verlag Berlin 1990 368 386
Evans P.Migration and orientation of passerine night migrants in northeast England J. Zool 1966 150 319 369
Hilgerloh G., Bingman V.P.Radar observations of Passerine migration over Frankfurt and Hannover, Germany J. Ornithol 1992 133 23 31
Hilgerloh G., Parada P.R.Zugverlauf und Zugziele von Transsaharaziehern während des Frühjahrs in Südwestspanien J. Ornithol 1988 129 227 231
Kiepenheuer J., Linsenmair K.E.Vogelzug an der nordafrikanischen Küste von Tunesien bis Rotes Meer Vogelwarte 1965 23 80 94
Lack D.Migration across the North Sea studied by radar Part 2. The spring departure 1956–59. Ibis 1960 102 26 57
Leshem Y., Following raptor migration from the ground, motorized glider and radar at a junction of three continents. WWGBP, Berlin, pp Meyburg B.-U., Chancellor R.D.1989 43 51
Liechti F.Flight behavior of nocturnal migrants in relation to wind and topography. Thesis, Universität. Basel (in German, English abstract) 1992
Liechti F.Nächtlicher Vogelzug im Herbst über Süddeutschland: Winddrift und Kompensation J. Ornithol 1993 134 373 404
Lindström Å., Alerstam T.The adaptive significance of reoriented migration of chaffinches Fringilla coelobs and bramblings F. montifringilla during autumn in southern Sweden Behav. Ecol. Sociobiol 1986 19 417 424
Safriel U.Bird migration at Elat, Israel Ibis 1968 110 283 320
Shirihai H., Christie D.A.Raptor migration at Eilat British Birds 1992 85 141 193
Szép T.Study of spring migration by weather radar in Eastern Hungary Ornis Hungarica 1992 2 17 24
| All Time | Past 365 days | Past 30 Days | |
|---|---|---|---|
| Abstract Views | 310 | 29 | 4 |
| Full Text Views | 20 | 0 | 0 |
| PDF Views & Downloads | 21 | 0 | 0 |
Flight paths of more than 40,000 nocturnal migrants were collected by tracking radars simultaneously at two sites in spring and autumn. Winds were similar in autumn and spring: i.e., typical, rather weak trade winds with northerly directions below about 1500 m above sea level and with southerly or westerly directions higher up. The tracks of the birds were concentrated around 190° (between S and SSW) in autumn and around 5° (nearly N) in spring. Slight differences between the directional distribution of birds above the Negev Highlands and the Arava Valley could be attributed mainly to local winds and topography. Reversed migration occurring in autumn was at the altitudes of the southwesterly winds. Tracks and headings of different wingbeat classes did not differ significantly, except that birds with low wingbeat frequency and passerine-type flight had more westerly directions in autumn and more easterly directions in spring. Mean groundspeed in autumn was nearly 50 km/h, most birds profiting from following winds. In spring many migrants had to fly against the wind, thus, the groundspeed was on average lower (45 km/h) and its variation much wider than in autumn. Mean airspeed, however, was slightly higher in spring than in autumn, indicating a tendency to compensate for opposing winds. In weak winds airspeeds of wader-type birds were slightly higher than those of passerines; surprisingly, small wader-and passerine-type birds with higher wingbeat frequencies were faster than those with slower wingbeats. A high proportion of nocturnal migrants belonged to the wingbeat class of passerine-type birds. In autumn, the proportion of passerines with fast wingbeats increased from about one third in August to almost 50% at the end of October. During August and September, about one third of the identified birds had a wader-type wingbeat pattern. In spring, the proportion of passerines decreased slightly from March till May, correspondingly the proportion of wader-type birds slightly increased.
| All Time | Past 365 days | Past 30 Days | |
|---|---|---|---|
| Abstract Views | 310 | 29 | 4 |
| Full Text Views | 20 | 0 | 0 |
| PDF Views & Downloads | 21 | 0 | 0 |