TY - JOUR
T1 - Orientation of shorebirds in relation to wind
T2 - both drift and compensation in the same region
AU - Johanna, Grönroos
AU - Alerstam, Thomas
AU - Green, Martin
PY - 2013
Y1 - 2013
N2 - Migratorymovements in air or water are strongly affected by wind and ocean currents and an animal which does not compensate for lateral flow will be drifted from its intended direction of movement. We investigated whether arctic shorebirds during autumn migration in the region of South Sweden and the southern Baltic Sea compensate for wind drift or allow themselves to be drifted when approaching a known goal area under different circumstances (over sea, over land, at low and high altitude) using two different approaches, visual telescope observations and tracking radar. The shorebirds showed clearly different responses to crosswinds along this short section (\200 km) of the migratory journey, from almost full drift when departing over the sea, followed by partial drift and almost full compensation at higher altitudes over land during later stages. Our study demonstrates that shorebirds are also remarkably variable in their response to crosswinds during short sections of their migratory journey. The recorded initial drift close to departure is probably not adaptive but rather a result of constraints in the capacity of the birds to compensate in some situations, e.g. in low-altitude climbing flight over the sea. We found no difference in orientation response to wind between adult and juvenile birds. This study indicates, in addition to adaptive orientation responses to wind, the importance of the nonadaptive wind drift that contributes to increasing the variability of drift/compensation behaviour between places that are separated by only short distances, depending on the local topographic and environmental conditions.
AB - Migratorymovements in air or water are strongly affected by wind and ocean currents and an animal which does not compensate for lateral flow will be drifted from its intended direction of movement. We investigated whether arctic shorebirds during autumn migration in the region of South Sweden and the southern Baltic Sea compensate for wind drift or allow themselves to be drifted when approaching a known goal area under different circumstances (over sea, over land, at low and high altitude) using two different approaches, visual telescope observations and tracking radar. The shorebirds showed clearly different responses to crosswinds along this short section (\200 km) of the migratory journey, from almost full drift when departing over the sea, followed by partial drift and almost full compensation at higher altitudes over land during later stages. Our study demonstrates that shorebirds are also remarkably variable in their response to crosswinds during short sections of their migratory journey. The recorded initial drift close to departure is probably not adaptive but rather a result of constraints in the capacity of the birds to compensate in some situations, e.g. in low-altitude climbing flight over the sea. We found no difference in orientation response to wind between adult and juvenile birds. This study indicates, in addition to adaptive orientation responses to wind, the importance of the nonadaptive wind drift that contributes to increasing the variability of drift/compensation behaviour between places that are separated by only short distances, depending on the local topographic and environmental conditions.
KW - Migration
KW - compensation
KW - orientation
KW - shorebird
KW - wind drift
U2 - 10.1007/s10336-012-0902-7
DO - 10.1007/s10336-012-0902-7
M3 - Article
VL - 154
SP - 385
EP - 392
JO - Journal of Ornithology
JF - Journal of Ornithology
SN - 2193-7192
ER -