In ancient Rome, the owl was seen as a bad omen, a bird that fed on human flesh and blood.
With the end of October near and Halloween decorations almost everywhere you look, you might be wondering why certain animals are so often featured as we approach the spookiest holiday. Why do plastic owls decorate lawns, and fake bats hang from every nook and cranny?
It’s because the eerie mythologies surrounding these creatures are long-standing traditions that were developed from earlier humans’ understandings—or fears—of the natural world.
Owls, especially, boast a complicated mythos that encompasses two, conflicting depictions: one as a wise, helpful mystic and the other as a guardian of the dead. This division stems from the contradictory views of ancient Greeks and Romans. Athena, the Greek goddess of wisdom, was often depicted with an owl companion. Her owl was hailed as a symbol of insight and knowledge, and, therefore, owls were treated with reverence within Greek culture.
When Halloween draws near, fake bats seem to hang from every nook and cranny.
On the other hand, in Roman mythology, the owl was seen as a bad omen—an animal that fed on human flesh and blood. When Rome defeated Athens in 146 B.C., this more malicious depiction of owls began to dominate both areas and spread out across the world. In fact, it was so pervasive that it affected Roman language. The Latin word strix meant not only owl, but also witch in the form of an owl and to utter shrill sounds.
Romans didn’t always believe that owls were natural creatures; instead they were often suspected of being witches that had transformed into owls to fly to a witches’ sabbath, or gathering. Even today, strix is used as the genus name for earless owls (or wood owls), including great gray owls and spotted owls.
Fast-forward to the present time, and we now marvel at owls for the negligible noise they create while flying. While many studies have linked the microfringes on owl wings to their silent flight, the exact mechanisms have been unclear. Now, a team of researchers has uncovered the effects of these microfringes on the aerodynamic performance and sound of owl wings through a computational fluid dynamic simulation, a numerical method that models the behavior of fluids using computational hardware and techniques. Their findings could inspire biomimetic designs for the development of low-noise, fluid machinery—devices that convert the energy stored by a fluid into mechanical energy (or vice versa).
Researchers have also recently upended the notion that the iconic great gray owl—among North America’s tallest owls and known as “the phantom of the North”—lives far from cities, towns and other markers of human density.
The powerful great gray owl has an intense stare and is one of the tallest owls in the United States. This bird is often known as “the phantom of the North.”
Of all wildlife species, though, bats seem to be the most intensively associated with Halloween, and for good reason. Bats have been a symbol of the holiday since its origins. Given their tendency to gather in the autumn before migration and hibernation, swarms of bats are a common sight at dusk this time of year.
Today, however, we’re also awed by these animals. For example, bats can carry deadly viruses but not develop symptoms. Researchers recently discovered that what happens during “swarming” behavior may hold the key to understanding their viral tolerance and could translate into human health by helping us fight off diseases like COVID-19 and Ebola.
Uncovering the secrets behind the silent flight of owls
Owls are fascinating creatures that can fly silently through some of the quietest places. Their wings make no noise while flying, enabling them to accurately locate their prey using their exceptional hearing ability while remaining undetected. This unique ability depends on many factors and has long been a hot research subject.
The quiet flight of owls is an act of biomechanical stealth that still challenges science. Only recently have biologists and engineers begun to unravel the secrets of how owls can fly silently, enabling them to accurately locate their prey using their exceptional hearing abilities while remaining undetected.
Studies have found associations between the ability to fly silently and the presence of microfringes on owl wings. These trailing-edge (TE) fringes play a crucial role in suppressing the noise produced by wing-flap-induced air movement. Studying these fringes can lead to the development of promising methods to reduce noise caused by fluid machinery. Scientists have conducted many studies to evaluate these fringes using flat plates and airfoils, but the exact mechanisms and effects on the interactions of feathers and the different wing features in real owl wings remained unknown—until recently.
To unravel those secrets, researchers at the Graduate School of Science and Engineering at Chiba University in Japan investigated how TE fringes influence both the aerodynamic performance and the sound of owl wings.
To understand how owl wings work, the research team constructed two three-dimensional models of a real owl wing—one with and the other without TE fringes. They used these models to conduct fluid-flow simulations that combined the methods of large eddy simulations and the Ffowcs-Williams-Hawkings acoustic analogy model. The simulations were conducted at the speed of the gliding flight of approach of a real owl.
Microfringes—soft fringes on the trailing edge of an owl’s wing—have been linked to these birds’ capacity for silent flight.
The simulations revealed that the TE fringes reduced the noise levels of owl wings, particularly at high angles of attack, and maintained an aerodynamic performance comparable to owl wings without fringes. The team identified two complementary mechanisms through which the TE fringes influence airflow. First, the fringes reduce the fluctuations in airflow by breaking up the trailing edge vortices. Second, they reduce the flow interactions between feathers at the wing tips, thereby suppressing the shedding of wing-tip vortices. Synergistically, these mechanisms enhance the effects of TE fringes, improving both aerodynamic force production and noise reduction.
Publishing their findings in the journal Bioinspiration and Biomimetics in November 2023, the scientists say that their work demonstrates the effect of complex interactions between the TE fringes and the various wing features. The silent flight of owls can inspire biomimetic designs that could lead to the development of low-noise fluid machinery, such as drones, propellers, wind turbines and even flying cars.
Providing a new picture of the great gray owl
Great gray owls live in the Russian Far East, Siberia, Kazakhstan, Lithuania, Manchuria, Mongolia and northeastern China. In North America, they live across central Alaska and Canada, as well as in parts of the northwestern and central Lower 48. But mostly, the great gray owl has long been thought of as a sentinel of the Alaska wilderness, keeping watch over snow-laden forests as far north as the Brooks Range, well away from human populations.
But in a study published in the journal Scientific Reports in March 2024, a team of University of Alaska Fairbanks researchers finds that the supposition that the bird lives far from our cities and towns just isn’t true.
The great gray owl has long been thought of as a sentinel of the Alaska wilderness, keeping watch over snow-laden forests and staying far away from human populations.
The study was conducted using artificial intelligence modeling that was given more than 100 predictors: environmental variables for specific locations, such as days of freezing per year and distance to human footprints like cities, towns, roads, runways and even the Trans-Alaska oil pipeline. Because the computing power was previously lacking, this marks the first time a computer modeling system has been used to do this specific kind of predicting. Combined with citizen science-sourced, publicly available biodiversity databases, the modeling identified the most suitable habitats for the owl.
The scientists used the software Random Forest, a commonly used machine-learning algorithm, to make inferences from the predictors. The computer model was trained using datasets from eBird.org, the Federal Aviation Administration’s bird-strike records, the Global Biodiversity Information Facility, iNaturalist.org, and various local and national bird-watching email lists.
A lack of scientific data has contributed to the myth that the birds are elusive and shrouded in mystery. Even their Latin name, Strix nebulosa, plays upon an association with witchcraft (strix) and cloudy or misty weather (nebulosa) (though the latter simply refers to the bird’s gray color).
So, what did the data reveal? Although we like to think of wildlife, especially in Alaska, as existing in pristine wildernesses untouched by humans, the Scientific Reports study shows that these owls congregate in much more populated areas near human-made structures.
Although we like to think of wildlife as existing in pristine wildernesses that are untouched by humans, scientific studies show that great gray owls often congregate in populated areas near human-made structures.
The researchers state that, rather than hanging onto traditional myths and narratives that are perpetuated about wildlife, we should use science to provide us with a much more holistic representation of where these owls live and in what kinds of environments.
Solving the next pandemic by studying bat “nightclubs”
Bats carry some of the deadliest zoonotic diseases that can infect both humans and nonhuman animals, including COVID-19 and Ebola. But in an article published in the journal Cell Genomics in February 2024, a Texas A&M University research team revealed that some species of bats are protected against the viruses they carry because they commonly exchange immune genes during seasonal mating swarms.
To uncover exactly how bats have evolved tolerance to these deadly viruses, the Texas A&M team and international research partners mapped the evolutionary tree of Myotis bats, a crucial step in trying to identify which genes might be involved. Myotis bats are the second-largest genus of mammals, with more than 140 species that all look similar. They’re found in almost every part of the world, and they host a large diversity of viruses.
Several bat species are tolerant of viruses that are detrimental to human health, which means they become reservoirs for disease—they carry the viruses, but they don’t develop symptoms.
To add to the difficulties associated with figuring out relationships among bats, Myotis and other bat species engage in swarming behavior during mating. Swarming behavior is like a social gathering: There’s lots of flight activity and increased communication and interspecies mingling—not unlike, say the researchers, people in a nightclub.
Complicating things for the researchers further, swarming creates increased numbers of hybrids—individual bats with parents from different species. So, while it’s already very hard to distinguish Myotis bats, hybridization makes it even more difficult. And when trying to map out how these bats evolved in order to understand their disease immunity, being able to tell who’s who is pretty important!
With this in mind, the scientists first untangled the genetic code for hybridization so they could more clearly tell which species were which. Then, by collaborating with researchers from France, Ireland and Switzerland, they sequenced the genomes of 60 Myotis bat species, allowing them to figure out which parts of the DNA represented true evolutionary history and which parts arose from hybridization.
Bat swarming is when individuals aggregate, typically in or near caves or mines during autumn. They repeatedly chase each other, circle, dive and land. It’s an interspecies social gathering; for bats, it’s not unlike going to a nightclub.
With that part of the puzzle solved, the researchers were able to examine the genetic code more closely to see how it might shed light on disease immunity. They found that immune genes were some of those most frequently exchanged between species while swarming. Swarming behavior had always been a bit mysterious for researchers, but now there’s a better understanding of why this particular behavior evolved; perhaps to promote hybridization, which helps spread beneficial immune gene variants more widely throughout the population.
Understanding how bats evolved viral tolerance may help us learn how humans can better fight emerging diseases and could hold the key to preventing the next global pandemic.
Wishing you a happy Halloween in all your dark corners
Many of us now enjoy having a cornucopia of wildlife living just outside our backdoors. We no longer believe that some of them—such as bats and owls—are imbued with frightening magical powers, or that they cavort with ghosts and witches.
Spooky myths linking bats and owls with Halloween are long-standing traditions that were developed from earlier humans’ understandings—or fears—of the natural world. Even now, on October 31, we tend to revisit the old superstitions regarding two animals that have come to symbolize the holiday.
On Halloween, though, we might be forgiven for revisiting some of nature’s long-held myths and superstitions—and, perhaps, for placing a plastic owl or hanging a fake bat or two in a dark corner.
Have a happy Halloween,
Candy
