Page 120 - Panuccio2012

Weather conditions and the visible migration of Short-toed Snake Eagles

Table 1 -Temperatures, barometric pressure and relative humidity during the two seasons.

Autumn Spring Mann-Whitney

Temperatures (°C) Min. 16 0 U-test= 38528
Median 23 11 P < 0.001
Barometric Mean 22.8 10.7 n = 398
Pressure (hPa) Max 28 19
U-test= 14514.5
Relative Humidity Min. 1009 1010 P < 0.001
(%) Median 1018 1021 n = 398
Mean 1018 1021
Max. 1027 1035 U-test =14177.5
P < 0.001
Min 29 26 n = 398
Median 56 66
Mean 56.1 63.6
Max. 100 94

Table 2 - Percentage of different wind directions in autumn and spring (HW = head wind; TW = tail
wind; LW = lateral wind).

Autumn (%; n = 230) Spring (%; n = 168)

Northerly 23.9 (HW) 47.0 (TW) 79

Southerly 24.3 (TW) 23.8 (HW) 40

Westerly 35.6 (LW) 11.9 (LW)

Easterly 6.1 (LW) 8.3 (LW)

Variable 8.3 0.6

No wind 1.7 8.3

Table 3 - Wind strength of prevailing winds in spring and autumn.

Westerly Head wind Tail wind
wind (km/h) (km/h) (km/h)

Autumn Min. 5.6 3.7 5.6 KW = 10.02
Spring Median 11.1 11.2 14.8 P > 0.05
Mean 11.7 12.9 14.1 n = 193
21.1 27.8 22.2
Max 1.7 U-test=2049
- 1.6 9.7 P < 0.01
Min. 8.0 12.3 n = 119
Median 8.6 48.2
Mean 47.9

Max

Table 4 -Hourly means of Short-toed Snake Eagles observed with different wind conditions.

Hourly Mean (± SE)

Autumn Spring

Head wind 2.1 ± 1.09 (n = 55) 4.77 ± 1.83 (n = 40)

Tail wind 1.3 ± 0.46 (n = 56) 4.03 ± 0.45 (n = 79)

Lateral (westerly) wind 1.85 ± 0.38 (n = 82) -

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