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Table 2 Correlation between arrival fuel load, tailwind components (TWC), relative humidity, sex and age. Separate models were run for both seasons, with each flight path aligned with a coastal destination (Fig. 1)

From: Days to visit an offshore island: effect of weather conditions on arrival fuel load and potential flight range for common blackbirds Turdus merula migrating over the North Sea

Autumn migration Wangerooge (43 km) Juist (80 km) Terschelling (177 km) Caister-on-Sea (442 km)
Intercept 2.415 (−2.521 to −2.302) 2.405 (−2.517 to − 2.301) − 2.411 (− 2.523 to − 2.307) − 2.413 (− 2.159 to − 2.307)
Tailwind components (linear) 0.017 (0.0090.025) 0.003 (− 0.006 to 0.012) − 0.004 (− 0.012 to 0.005) − 0.006 (− 0.014 to 0.003)
Relative Humidity (linear) 1.499 (− 0.104 to 3.215) 2.136 (0.5923.630) 1.887 (0.3593.516) 1.832(0.2903.474)
Relative Humidity (quadratic) − 0.526 (− 2.089 to 1.033) 1.600 (0.0313.080) 1.512 (0.0643.046) 1.445 (− 0.013 to 2.971)
Sex 0.078 (− 0.066 to 0.222) 0.071 (− 0.070 to 0.214) 0.073 (− 0.068 to 0.215) 0.073 (− 0.069 to 0.216)
Age 0.517 (0.3790.654) 0.532 (0.3930.672) 0.522 (0.3850.661) 0.517(0.3770.658)
Interaction (Sex:Age) − 0.229 (− 0.417 to − 0.034) − 0.230 (− 0.419 to − 0.036) − 0.231 (− 0.420 to − 0.043) − 0.227 (− 0.417 to − 0.036)
Spring migration St. Peter-Ording (49 km) Amrum (61 km) Blåvand (155 km) Mandal (429 km)
Intercept − 2.199 (− 2.236 to − 2.004) − 2.042 (− 2.157 to − 1.930) − 1.985 (− 2.094 to − 1.879) − 1.970 (− 2.077 to − 1.866)
Tailwind components (linear) 0.024 (0.0140.034) 0.017 (0.0030.030) − 0.002 (− 0.017 to 0.015) − 0.011 (− 0.026 to 0.005)
Relative Humidity (linear) 1.518 (− 0.185 to 3.328) 2.135 (0.4253.999) 2.443 (0.7104.347) 2.117 (0.3943.998)
Relative Humidity (quadratic) − 1.896 (− 3.685 to − 0.024) − 0.533 (− 2.290 to 1.232) − 0.617 (− 2.398 to 1.167) − 0.245 (− 1.993 to 1.474)
Sex − 0.238 (− 0.394 to − 0.083) − 0.264 (− 0.422 to − 0.108) − 0.283 (− 0.438 to − 0.128) − 0.285 (− 0.441 to − 0.131)
  1. During autumn migration, the two-way interaction of sex and age was included. Mean estimates and CrI are presented for each explanatory variable (transformed values; see methods). Effects (CrI do not include zero) are shown in bold. Reference category for age was first-years and for sex males