Mognud rannsokn

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Magnetic alignment in grazing and resting cattle and deer

1. Sabine Begall*,^†,
2. Jaroslav Červený^‡,^§,
3. Julia Neef*,
4. Oldřich Vojtčch^‡,^¶, and
5. Hynek Burda*

+Author Affiliations

1. *Department of General Zoology, Faculty of Biology and Geography, University of Duisburg-Essen, 45141 Essen, Germany;
2. ^§Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, 60365 Brno, Czech Republic;
3. ^‡Department of Forest Protection and Wildlife Management, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, 16521 Praha 6, Czech Republic; and
4. ^¶Sumava National Park Administration, Susicka 399, 341 92 Kasperske Hory, Czech Republic

1. Edited by Simon A. Levin, Princeton University, Princeton, NJ, and approved July 17, 2008 (received for review April 15, 2008)

Abstract

We demonstrate by means of simple, noninvasive methods (analysis of satellite images, field observations, and measuring “deer beds” in snow) that domestic cattle (n = 8,510 in 308 pastures) across the globe, and grazing and resting red and roe deer (n = 2,974 at 241 localities), align their body axes in roughly a north–south direction. Direct observations of roe deer revealed that animals orient their heads northward when grazing or resting. Amazingly, this ubiquitous phenomenon does not seem to have been noticed by herdsmen, ranchers, or hunters. Because wind and light conditions could be excluded as a common denominator determining the body axis orientation, magnetic alignment is the most parsimonious explanation. To test the hypothesis that cattle orient their body axes along the field lines of the Earth's magnetic field, we analyzed the body orientation of cattle from localities with high magnetic declination. Here, magnetic north was a better predictor than geographic north. This study reveals the magnetic alignment in large mammals based on statistically sufficient sample sizes. Our findings open horizons for the study of magnetoreception in general and are of potential significance for applied ethology (husbandry, animal welfare). They challenge neuroscientists and biophysics to explain the proximate mechanisms.