Deer Sense the Earth’s Magnetic Field

A herd of roe deer on snow.  (Click for credit)

A herd of roe deer on snow. (Click for credit)

There are many animals that sense the earth’s magnetic field. Monarch butterflies, for example, sense the magnetic field and use it to aid in navigation during their amazing migration.1. Salmon seem to “imprint” a picture of the earth’s magnetic field at the point where they enter the ocean, and they later use that imprint to navigate back to that same point when they return to their birthplace to spawn. Homing pigeons also sense the earth’s magnetic field and use it as a part of their navigation.

Years ago, I read about a study that seemed to say cattle tend to align with the earth’s magnetic field while they graze. It perplexed many scientists, and some didn’t want to believe it. After all, cattle don’t navigate long distances! Why in the world would they need to sense the earth’s magnetic field? However, the study seemed to stand up to scrutiny. When I am speaking, I often use it as an example of experimental data that make no sense, but nevertheless seem to be true. I further suggest that rather than fighting against the conclusion of the study, someone should try to figure out why cattle seem to have a magnetic sense.

Well, no one (to my knowledge) has done that for cattle, but someone has done it for roe deer, which are pictured above. Roe deer tend to congregate in flat areas, so their herds are easy to watch from a distance. Researchers studied them in 60 different locations in three hunting grounds in the Czech Republic. They observed the way the deer faced while they were grazing and, more importantly, how the deer reacted when they were startled.

They found that the deer tend to align their bodies along north/south magnetic field lines while grazing. Then, when startled, they tend to run north or south, regardless of the direction from which the threat comes. These behaviors were more pronounced when the deer were in large herds.2

Why do the deer bother sensing the earth’s magnetic field? Based on their observations, the authors suggest:

…an important function of this behavior is to coordinate the movement in the group, to keep the common course of escape when frightened and to maintain the cohesion of the group.

In other words, it helps the deer escape without running into one another, and it helps them regroup once the threat is gone.

The authors say that this is the first confirmed case of mammals using the earth’s magnetic field to navigate. I suspect that it is merely the first of many. The more I learn about Creation, the more in awe I am of its Creator.


1. Patrick A Guerra, Robert J Gegear, & Steven M Reppert, “A magnetic compass aids monarch butterfly migration,” Nature Communications 5:4164, 2014, doi:10.1038/ncomms5164
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2. Petr Obleser, Vlastimil Hart, E. Pascal Malkemper, Sabine Begall, Michaela Holá, Michael S. Painter, Jaroslav Červený, and Hynek Burda, “Compass-controlled escape behavior in roe deer,” Behavioral Ecology and Sociobiology, 06 June 2016, DOI:10.1007/s00265-016-2142-y
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  1. Lawrence Dol says:

    And yet, still Dawkins and his ilk insist that the evidence of design is just illusory. Not to mention that this is a terrific case of convergence which evolution is hard-put to explain.

  2. cjl says:

    I’ll have to remember this at the inevitable moment when the deer I’m hunting run away! : ) Fascinating fact!

    1. Jay Wile says:

      Aim north and south, I guess!

  3. Paul Austin says:

    How was the explanation that animals align to the sun, for thermoregulation, excluded as a possibility? In other words, in cool-temperate regions, animals may stand side-on to the sun in the morning and late afternoon to receive warmth, and de-orientate in the middle of the day. Seems a lot simpler …

    1. Paul Austin says:

      In addition, being social, moving herds will tend to orient with the dominant member, which will reinforce a pattern. So (for instance) if the alpha member emerges first from shelter and orients to the sun, others will follow its lead.

      1. Jay Wile says:

        They note that when startled, individuals don’t necessarily follow the alpha. Some go north, and others go south. If they were following the lead of the alpha, you would think they would all go the same direction as the alpha. Also, if the herd is just imitating the alpha, why does the alpha preferentially align along the magnetic field lines? They observed several different herds in several different places, and all herds exhibited the alignment tendency.

    2. Jay Wile says:

      They specifically made their observations at several different times of the day and under several different weather conditions (cloudy, sunny, warmer, cooler, etc.). They saw no correlation between orientation and weather conditions or time of day, and they saw no correlation between escape behavior and those parameters.

      1. Paul Austin says:

        As we know, correlation and causality are different things, and likewise no significant correlation does not mean no relationship. Statistically, 188 observations is not many data, given the number of variables at play, and an expected weak relationship with what might be the primary “causal” factors. Teasing these apart is tricky, even with more statistical ‘power’.

        I have toyed in the past with how to test the original “magnetic cow” suggestion, using dairy herd observations (I live in a dairy production region – plenty of cows, large herds several hundred plus in number). I decided it was not going to be easy, given a westerly prevailing wind, and herd behaviour which will mean individual cow orientations are strongly correlated so do not provide replication. Aerial images (drone) might be a way to get data, but only if we know herd dominance relationships reliably, and how it affects orientation – not easy given herd sizes, daily movement patterns and grazing management.

        I am surprised the paper got through the editorial process. I don’t think the field deer survey design, and number data points offered, allows the magnetic orientation hypothesis to be distinguished from the alternative that the animals are simply orienting to the sun (i.e., N-S or S-N for warmth on their flanks in the morning & afternoon, and ditto in the middle of the day to minimise exposed area and stay cooler). The two factors are inherently confounded in an uncontrolled field situation.

        1. Jay Wile says:

          You are certainly right that correlation doesn’t necessarily mean causality, but I think they make a strong case. I am not at all surprised it passed peer review, as it is a well-designed study. It ruled out the idea of aligning with the sun, since the alignment didn’t correlate with time of day, temperature, or cloud cover.