Deer Line Up North-South, Whether Relaxing or Running

By Elizabeth Preston | July 27, 2016 1:38 pm

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If you’re ever lost in a remote European forest, you might be able to get your bearings by finding a herd of roe deer. These animals like to align themselves roughly north-south, whether they’re standing still or fleeing danger.

Roe deer are small, reddish or grayish grazers common in Europe and Asia. Petr Obleser, of the Czech University of Life Sciences in Prague, and his coauthors studied the behavior of these skittish herbivores to look for evidence that they can sense the earth’s magnetic field. 

Two men separately patrolled the Czech countryside for deer. They went on foot, wearing olive-green hunting gear and carrying binoculars. Whenever an observer spotted a roe deer, he stopped and recorded how the deer was oriented: East-west? Northwest-southeast? Then he continued walking toward the animal. When it fled, he recorded the direction it had run in.

The researchers were able to gather data on 188 deer. Of these, 115 deer were on their own. The rest were in groups of 2 to 5 animals.

How the deer were standing when researchers found them was not random. Deer were most likely to stand along a north-northeast by south-southwest axis. This tendency was stronger when deer were in a group than when they were alone. The time of day, season, wind, position of the sun, or type of habitat didn’t affect how the animals were standing. So the researchers concluded that roe deer can likely sense the earth’s magnetic field—and line themselves up according to it.

As the observers got closer, deer also tended to flee in either a north-northeast or south-southwest direction. If someone was approaching a deer’s side rather than its head or tail, this meant the deer might run at an angle instead of straight away from the person.

Biologists call a tendency to line up in one seemingly arbitrary direction a “nonsense orientation.” Other researchers have seen similar behavior in birds. There’s no particular reason that facing roughly north or south should be better than other directions. In fact, sticking to one alignment when running from a predator—rather than just going in the opposite direction of the threat—seems like a bad idea.

But Obleser and his coauthors think their magnetic preferences might help roe deer nonetheless. If the deer in a herd (or the birds in a flock) all tend to flee in one direction, it could help the group stay together even when it’s in panic mode. There may be some sense, then, to the nonsense.


Image by John Clift (via Flickr)

Obleser, P., Hart, V., Malkemper, E., Begall, S., Holá, M., Painter, M., Červený, J., & Burda, H. (2016). Compass-controlled escape behavior in roe deer Behavioral Ecology and Sociobiology, 70 (8), 1345-1355 DOI: 10.1007/s00265-016-2142-y

CATEGORIZED UNDER: earth, friends, navigation, top posts
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  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    If you’re ever lost in a remote European forest, you might be able to get your bearings by finding a herd of roe deer,” Stick a stick into the ground normal to the Earth’s geoid. The shadow at noon is south near enough. The shadow is always southerly north of the Equator. Moss likes the southerly cooler side of trees. Big Dipper to Polaris at at night for north.

    Stick a Helmholz coil pair across a deer’s head and neck, battery, and remote controller. then, Youtube v=EhbxI5eVnM4, 2:26ff (transcranial magnetic stimulation hoo-hah). Observed factual reality re Galileo and Popper – soon to be Executive Order ended by HER.

    • Derek Hall

      Out by 180˚

      • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

        Sssssh! The proletariate believes anything in a suit. The bourgeoisie sometimes requires a lab coat. Do people question Official Truth given observed reality? Overall, no: HER.

  • polistra24

    The exact direction is interesting. Declination in central Europe appears to be a little W of N, not a little E of N. This hasn’t changed much in recent decades. Presumably a magnetic sensor would be bilateral and symmetrical like other senses, not intrinsically angled. When you’re seeking a scent or a light or a sound with bilateral transducers, you try to stay “on beam”, not aim away from it. No reason to think a mag sense would be any different.

    The deer must be making a “software adjustment” to the mag-sense beam, based on some earlier era when this “recalibration” helped survival.

    • polistra24

      Here’s what I was thinking of. Took a while to find it. Nematodes make a similar “software adjustment” for INclination. The calibration appears to be semi-permanent, controlled through epigenes.

      https://elifesciences.org/content/4/e07493v1

  • jolangb

    Rather a shame that in writing about a paper on Roe deer (Capreolus c.) the picture at top of article actually shows Fallow deer (Dama dama) which are not at all the same or even closely related species.

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Inkfish

Like the wily and many-armed cephalopod, Inkfish reaches into the far corners of science news and brings you back surprises (and the occasional sea creature). The ink is virtual but the research is real.

About Elizabeth Preston

Elizabeth Preston is a science writer whose articles have appeared in publications including Slate, Nautilus, and National Geographic. She's also the former editor of the children's science magazine Muse, where she still writes in the voice of a know-it-all bovine. She lives in Massachusetts. Read more and see her other writing here.

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