Blue Ridge Naturalist: Behind Every Scientific Myth Is a Scientist

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©Marlene A. Condon

According to legend, this male mantis (the one on top) is done for. (Photo credit: Marlene A. Condon)
According to legend, this male mantis (the one on top) is done for. (Photo credit: Marlene A. Condon)

Like most people, you probably have no idea that the story of a female mantis decapitating and eating the head of the male before, during, or after sexual relations is a myth. The worst aspect of this myth is that it originated with a bona fide scientist!

Leland Ossian Howard, who was educated at Cornell University, was the chief entomologist of the U. S. Department of Agriculture from the late nineteenth century well into the beginning of the twentieth. He is credited with making the study of insects (entomology) a legitimate branch of the biological sciences.  Unfortunately, his report of mantis mating behavior was not one of his finer moments as a researcher.

As described in the October 8, 1886, issue of the journal Science, Howard brought a male Carolina Mantis (our native species) to the home of a friend who’d been keeping a solitary female in a jar as a pet. When he placed the male, which is smaller than the female, into the jar, it tried to escape—with good reason.

Within a few minutes, the bigger female had grabbed the male and proceeded to feed upon him. Despite this, the male eventually managed to mate with the female after apparently realizing (according to Howard) that he was with a mantis of the opposite sex. Mr. Howard concluded that, “it seems to be only by accident that a male ever escapes alive from the embraces of his partner.”

The research scientist claimed the female “had always been plentifully supplied with food” and “was apparently full-fed,” but obviously he was wrong. His description of her feeding behavior is that of a ravenous individual.

It should go without saying that if you confine two predators to a limited space from which neither can escape, one is going to kill the other when it gets hungry enough.  In the natural world, size is usually the determining factor as to who the victor will be. Thus it should be expected that the larger female mantis would be the individual in the jar to get a meal.

As the years were passing by without my having ever seen a female mantis of any species (we have at least three in our area) devour her mate, despite the fact that I’d seen plenty of mating mantises in the wild, I began to become suspicious of the oft-repeated story about these insects. As someone who is always paying attention to the world around me, I knew I should have witnessed this event if it were indeed the common mating behavior of mantises.

I wasn’t at all surprised when I tracked down the anecdotal evidence for this assertion to find that the two mantises had been confined to a jar.  They weren’t out in the real world but, rather, in a limited amount of space.

What did surprise me was that this story, which is the source of the continuing urban legend, had found its way into print by way of an actual scientific publication. The mantis experiment was apparently considered legitimate science, presumably simply because it had been done by a certified scientist.

But it illustrates a serious problem that has continued to this day in the biological sciences. People think they can learn the truth about nature by setting up artificial conditions in a lab, but the natural world is far too complex for anyone to reliably replicate it for study. There are just too many variables. If you want to know the truth about nature, you must observe the real thing in the real world without interfering with it.

Almost exactly a century after the mantis “discovery” was published, flawed scientific analysis again found its way into the popular press, where it is referenced to this day.

Just last year National Geographic News published an essay regarding the 1980s study conducted by Stanley A. Temple, an avian ecologist, and his graduate student, Margaret C. Brittingham, to find out if bird feeding caused birds to become dependent upon feeders. In other words, if feeder food were suddenly taken away from birds that were accustomed to obtaining it in a particular location, would the birds be able to survive without such handouts.

The experiment was done in the real world as opposed to a lab, which was a step in the right direction. However, the scientists jumped to conclusions that weren’t supported by the design of their study.

At Devil’s Lake State Park in Wisconsin in the winter of 1984-1985, feeders that had been stocked with seeds every winter for 25 years were removed by researchers.  They then compared the survival rate of Black-capped Chickadees in that area to the survival rate of this species in an area where there had never been feeders.

Dr. Temple informed the National Geographic writer that these results “provided no evidence for harmful effects of forcing the Devil’s Lake ‘feeder addicts’ to go ‘cold turkey’.” The implication, which the writer duly went on to inform readers (as have many writers since the Temple/Brittingham study was published) was that it was therefore okay for folks to suddenly stop feeding birds during the winter if, for example, they wished to go away for several days.

But applying the results from a study done in one type of environment (“remote wooded areas where human habitation was limited”) to a totally different kind of environment (urban and suburban areas where often there won’t be much natural vegetation to provide an alternate food source) isn’t acceptable. The results will not necessarily be the same.

Especially surprising is how the researchers denied their own results to conclude that most species of feeder birds aren’t harmed when feeders are left empty in winter.  The Temple/Brittingham study found that “69 percent of the birds that were using feeders were still alive the following spring, while only 37 percent lived through the winter without access to feeders.” That’s a stunningly remarkable difference in survival!

Most perplexing to me is how the final conclusions drawn from this research could have been acceptable to the grad student’s thesis advisor, her dissertation committee, the Ph.D.-granting university, and the prestigious Cornell Lab of Ornithology that publicized these conclusions in Living Bird magazine.

Equally baffling is that another scientist—Dr. Stephen W. Kress, a well known ornithologist—referenced this study when he wrote in the 2000 January-February issue of Audubon magazine that “it is likely the birds that visit your feeders will not suffer if you leave your feeders empty for a few weeks of winter vacation.”

But on the contrary, the Temple/Brittingham study strongly suggests that if you went on vacation just as the weather turned bitterly cold this past February, for example, and you left your feeders empty, you likely had some bird mortality as a result. According to their study, Black-capped Chickadees did benefit from the availability of feeders during periods of frigid temperatures, with 93 percent of feeder birds surviving such conditions compared to only 67 percent of individuals without access to a feeder.

Indeed, Eastern Bluebirds and Carolina Wrens (along with some other species of birds and mammals) took a big hit in February of 2015 because of extreme cold and limited access to natural foods because of snow.

When it comes to the natural world, just because a scientist says it’s so doesn’t mean that it actually is.

1 COMMENT

  1. Ah, Marlene, what a wonderful new article! Once again observations trump what we read it books! I also appreciate the stunning example of the fallibility of “scientific” studies.

    I recall the good old days when I accepted most of what I read without question. I had the rude awakening to learn as an old woman that everything deserves careful scrutiny based on my experience with “restoration” ecology, which was spawned by invasion biology. Here are a couple of examples in my bailiwick:

    • How many times have you read that “invasive” species are the second greatest cause of extinction? That claim is nearly 20 years old and it has been cited over 700 times according to Mark Davis who finally debunked it in his book in 2009: http://milliontrees.me/2011/05/22/non-native-species-are-not-the-second-greatest-threat-to-species-in-peril/
    • How many times have you read that “invasive” species are costing the US over $120 billion per year? This is another bogus claim that does not stand up to scrutiny: http://milliontrees.me/2011/02/14/estimates-of-economic-impact-of-invasive-species-fail-smell-test-2/

    Both of these fallacies persist because correcting misinformation is never as influential as the original misinformation. People don’t like to change their minds.

    Thank you, Marlene. Keep up your good work.

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