Table 1 Effects of atmospheric conditions and altitude on far eastern curlew’s and whimbrel’s flight altitude selection as estimated using conditional logistic mixed effect modelling. All explanatory variables are scaled. Matched sample size of the model was 6127, including 482 cases, in far eastern curlew and 1832, including 146 cases, in whimbrel. Coefficients of variables, standard errors (SE), 95% confidence intervals (CIs), odds ratios and associated p-values of variables are presented. P < 0.05 are shown in bold. The interaction between altitude and air temperature is included to account for collinearity

Far eastern curlew

σ²

Std. dev.

 Altitude

−2.19 (0.44)

−3.05/−1.33

0.11

−4.99

< 0.001

 Wind support

0.83 (0.15)

0.55/1.12

2.30

5.73

< 0.001

 Cloud cover

−0.38 (0.10)

− 0.58/− 0.19

0.68

−3.80

< 0.001

 Relative humidity

0.20 (0.17)

−0.13/0.53

1.22

1.18

0.24

 Air temperature

−0.58 (0.45)

−1.45/0.30

0.56

−1.29

0.20

 Altitude: Air temperature

−0.21 (0.08)

−0.36/− 0.06

0.81

−2.69

< 0.01

 Individual

–

–

–

–

–

 Altitude

−2.56 (0.94)

−4.41/−0.71

0.08

−2.71

< 0.01

 Wind support

0.59 (0.26)

0.08/1.10

1.81

2.27

< 0.05

 Cloud cover

−0.04 (0.23)

−0.49/0.41

0.96

−0.17

0.86

 Relative humidity

−0.51 (0.29)

−1.09/0.06

0.60

−1.76

0.08

 Air temperature

−0.61 (0.98)

−2.53/1.30

0.54

−0.63

0.53

 Altitude: Air temperature

−0.32 (0.13)

−0.58/− 0.06

0.73

−2.45

< 0.05

 Individual

–

–

–

–

–