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Table 2 Magnetic North versus geographic North as reference for the preferred heading direction (μ) during landing on water surface in the mallard (or diverse other species of water birds in the case of Botswana)

From: Directional compass preference for landing in water birds

Country Magnetic declination Number of flocks Mean vector (mN) mμ Mean vector (gN) gμ Delta (mN, mμ) Delta (gN, gμ)
Botswana I -8° 264 356°/176° 344°/164° 12°
Botswana II -15° 85 0°/180° 345°/165° 15°
Canada 17° 136 354°/174° 11°/191° 11°
Czech Rep. 1,095 7°/187° 10°/190° 10°
Estonia 168 14°/194° 21°/201° 14° 21°
Finland 218 9°/189° 17°/197° 17°
Italy 394 9°/189° 12°/192° 12°
Poland 381 13°/193° 17°/197° 13° 17°
  1. Mean magnetic declination (angular difference between geographic North and magnetic North) is given for each locality. gμ and mμ denote the axial mean vectors (given as XX°/XX°) with reference to magnetic North (mN) and geographic North (gN), respectively. All mean values are highly significant (Rayleigh test, p < 0.000000001, 0.462 < r < 0.848). Delta refers to the smallest angle between mN and mμ (and gN and gμ, respectively).