Extremely low-frequency electromagnetic fields disrupt magnetic alignment of ruminants

Abstract

Resting and grazing cattle and deer tend to align their body axes in the geomagnetic North-South direction. The mechanism(s) that underlie this behavior remain unknown. Here, we show that extremely low-frequency magnetic fields (ELFMFs) generated by high-voltage power lines disrupt alignment of the bodies of these animals with the geomagnetic field. Body orientation of cattle and roe deer was random on pastures under or near power lines. Moreover, cattle exposed to various magnetic fields directly beneath or in the vicinity of power lines trending in various magnetic directions exhibited distinct patterns of alignment. The disturbing effect of the ELFMFs on body alignment diminished with the distance from conductors. These findings constitute evidence for magnetic sensation in large mammals as well as evidence of an overt behavioral reaction to weak ELFMFs in vertebrates. The demonstrated reaction to weak ELFMFs implies effects at the cellular and molecular levels.

Fig. 1.

Axial data revealing body orientation of domestic cattle (Bos taurus) (Upper) and roe deer (Capreolus capreolus) (Lower). (A, Left) Animals at localities without high-voltage power lines. (B) Animals grazing and resting under or in the vicinity of power lines. (Center) Bearings relative to the geomagnetic N-S axis. (Right) Bearings of body axes relative to power line direction. Each pair of data points (located on opposite sites within the unit circle) represents the direction of the mean axial vector of the herd. The double arrows indicate the length (r) and direction of the grand mean axial vectors. The inner circles mark the 5% (dotted) and 1% significance borders of the Rayleigh test. (Copyright 2008, National Academy of Sciences.)

Fig. 2.

Magnetic field properties and body orientation of cattle directly under power lines. Power lines trending in the ranges of 70°–110°, 340°–20°, 115°–155° and 25°–65° were classified as E-W (A), N-S (B), NW-SE (C), and NE-SW (D), respectively. The total intensity vector of the field (T) can be resolved into 2 vector components: the horizontal field intensity (H) and the vertical field intensity (V). The inclination is a vertical angle between the H (or the Earth's surface) and T. The azimuth is a horizontal angle measured clockwise between the horizontal intensity vector of the EMF (H₀) and the horizontal intensity vectors of the fields resulting from summation of the AMF and EMF (H₁ or H₂). B_AF, AMF vector; H₀, V_0, T₀, vectors of the EMF; H₁, H₂, V₁, V₂, T₁, T₂, vectors of the fields resulting from summation of the AMF and the EMF (the actual field oscillates between H₁ and H₂, V₁ and V₂, and T₁ and T₂, respectively, with a frequency of 50 Hz). Axial alignment data presented as in Fig. 1. See Tables S1 and S2 for numerical values.

Fig. 3.

Body alignment of individual cows as a function of the distance from E-W (B and D) and N-S power lines (C and E). (A) Decrease of the AMF intensity with the distance from conductors. Predicted (B and C) and observed (D and E) alignment patterns. See text and Table S3 for detailed information. Each pair of data points (located on opposite sites within the unit circle) represents the body axis of an individual cow. The double arrows indicate the length (r) and direction of the mean axial vector.

Fig. 4.

(A) Magnetic field characteristics north and south of E-W power lines, respectively (see Table S4 for numerical values). Alignment of cattle grazing south (B) or north (C) of E-W power lines. Alignment data are given relative to magnetic North (i.e., 0° = mN) and presented as in Fig. 1. B_AF, AMF vector; H₀, V_0, T₀, vectors of the EMF; H₁, H₂, V₁, V₂, T₁, T₂, vectors of the fields resulting from summation of the AMF and the EMF (the actual field oscillates between H₁ and H₂, V₁ and V₂, and T₁ and T₂, respectively, with a frequency of 50 Hz).