Tag Archives: UV light

How UV lights could end up saving crane species

Cranes are some of the most iconic bird species in the world — but they’re declining rapidly due to several factors, most of which involve human activity. Lethal collisions with power lines, for instance, are an ongoing threat to many crane populations. Several approaches have been tried to make these lines more visible, with varying degrees of success.

Now, a new study reports that adding UV lights — to which many birds are highly sensitive — can decrease crane collisions with power lines by 98%.

Cranes are a family of long-legged birds inhabiting all continents except Antarctica and, mysteriously, South America. Most species of cranes are dependent on wetlands and require large areas of open space. They tend to fly over large distances, although some species don’t migrate at all. For decades, researchers have reported that some cranes tend to fly into power lines, which is extremely dangerous to the birds and can easily be fatal.

James Dwyer and his colleagues from EDM International, an electrical utility company, created what they call the Avian Collision Avoidance System, or ACAS. The system essentially involves a set of UV lights mounted on power lines’ supporting structures.

They tested its effectiveness in 2018 at Nebraska’s Iain Nicolson Audubon Center, where a power line crosses right through a key habitat for migrating Sandhill Cranes. Randomly switching the ACAS on or off each night, researchers observed the behavior of cranes flying along the river at dusk and during the night. They documented 98% fewer collisions and 82% fewer dangerous flights when the ACAS was on.

“This project came about as a result of years of studying avian collisions with power lines throughout North America. My studies included collisions involving numerous species and families of birds, even on lines modified to industry standards to mitigate avian collisions, and I thought perhaps there could be a more effective approach,” says Dwyer.

Even so, the results were so good that they surprised even him.

“I did not imagine that the ACAS would have the effect that it did–a 98% reduction in collisions! I thought it would have some effect, but I didn’t dare think the ACAS would pretty much solve the Sandhill Crane collision problem at our study site on our first try,” he adds.

This is still a case study — the technology needs to be verified on multiple types of power lines and in multiple habitats. Dwyer also says that effectiveness ACAS needs to be investigated on other smaller species, which may also be at risk of collision with power lines.

“Because large carcasses like those of cranes and waterbirds are more easily noticed than smaller species like sparrows and warblers, collision studies have mostly focused on those larger species, and I fear that we may not understand the true distribution of species and habitats involved in the global avian collision problem.”

The study was published in The Condor: Ornithological Applications.

Credit: Pixabay.

Sunlight kills indoor germs almost as well as UV rays

We know that sunlight is important to our health, regulating sleep and mood. A new study, however, suggests sunlight also keeps us healthy by destroying bacteria that lurk indoors. The sanitizing effects are impressively close to those of ultraviolet light.

Credit: Pixabay.

Credit: Pixabay.

For their experiment, researchers at the University of Oregon collected dust from homes in Portland and placed it in dollhouse-sized rooms. The dust inside the tiny rooms — and the microscopic creatures that lived within — stayed there for 90 days under three conditions: exposed to daylight through regular glass; UV light alone; and total darkness.

When the team counted and inspected the bacterial samples, they were surprised by what they found. Lit rooms seem to harbor only half as many viable bacteria when compared to dark rooms, and nearly as few as those in the UV room. Researchers found 12% of bacteria in dark rooms were viable, compared to 6.8% in daylit rooms and 6.1% in rooms with UV light only, according to the findings published in the journal Microbiome. 

Ultraviolet (UV) light is a form of light that is invisible to the human eye, occupying the portion of the electromagnetic spectrum between X-rays and visible light. One of the biological characteristics of UV light is that it is germicidal – meaning it is capable of inactivating microorganisms, such as bacteria, viruses, and protozoa.

Today, UV light-based devices are used for drinking and wastewater treatment, air disinfection, the treatment of fruit and vegetable juices, as well as a myriad of home devices for disinfecting everything from toothbrushes to tablet computers. But soon enough, smart blinds that allow some of the solar energy to pass through and kill germs for us may become commonplace in our homes.

The study’s results were quite unexpected, however, because glass is known to block out most UV rays. The findings suggest that having a well-lit room can help protect residents from all sorts of infections. For instance, some of the bacterial species that didn’t survive the daylight rooms are known to cause respiratory disease.

“Our experimental and simulation-based results indicate that dust contains living bacterial taxa that can be inactivated following changes in local abiotic conditions and suggest that the bactericidal potential of ordinary window-filtered sunlight may be similar to ultraviolet wavelengths across dosages that are relevant to real buildings,” the authors concluded.

Next, the team plans to gain a more nuanced look at the relationship between daylight exposure and bacterial inactivation. This way, architects can then design the perfect windows that are just big enough to let enough light in to kill dangerous germs. But, perhaps the most important takeaway is that you should pull the blinds and let some of that light shine your room for longer during the day.


Australian skinks will literally stick their tongues out at predators — and it works!

When in doubt, stick your tongue out at them!


“You asked for it punk!”
Image credits Shane Black.

Skinks in the genus Tiliqua are pretty inconspicuous as far as lizards go. They don’t really like to draw attention to themselves, and they’re decidedly lizard-shaped. New research shows that when their unassuming nature fails to garner the peace of mind they desire (from predators), the skinks fall back to a surprising — and surprisingly effective — last-ditch defense: their tongues.

Their what now?

Bluetongued skinks are fairly widely spread throughout Australia, eastern Indonesia, and Papua New Guinea. They’re omnivorous, mediumly-sized lizards that primarily rely on their camouflage to keep out of sight. When under attack by a determined predator, however, they make an effort to stand out: the skinks open their mouth suddenly, as wide as they can, to reveal a brightly-colored blue tongue. Not to make them self-conscious but these tongues must be a sight to recoil from — because that’s exactly what predators do.

The behavior is used as a last line of defense to protect the skinks from attack, writes Martin Whiting, the study’s corresponding author, in a press release. The research revealed that the tongues are very reflective in the UV spectrum, and that they are more UV-luminous towards the back. Some of the lizards’ main predators, such as birds, snakes, or monitor lizards, are thought to be able to see UV light, suggesting the skinks might use this light to startle predators into breaking off their attack.

The study focused on the northern bluetongue skink (Tiliqua scincoides intermedia), the largest species of the group. The species sports good camouflage: broad brown bands across their backs to blend them into their surroundings. However, some of its main predators can still spot them, likely due to their ability to perceive UV light — so the team aimed to determine what tactics it uses to deter attackers.

First, they used a portable spectrophotometer to measure the color and intensity across different areas of the tongues of 13 skinks. This revealed that the blue tongues actually reflect UV light. Further data crunching in the lab later revealed that the tongues were almost twice as bright at the rear compared to the tip.

Mean spectra of different regions of the tongue. Associated illustration by Courtney Walcott of a Bluetongue skink performing a full-tongue display.
Image credits A. Badiane et al., 2018, Behavioral Ecology and Sociobiology.


The next part of the study was to identify how this bright tongue benefited the skinks. The team observed that skinks in the wild would open their mouths and stick their tongues out at would-be attackers. To find out more, the team simulated attacks on the lizards using models of their natural predators — the team used a snake, a bird, a goanna (monitor lizard), a fox — and a piece of wood as a control.

Skinks will rely on concealment for as long as they possibly can, the team reports. Should this fail, however, the lizards open their mouths widely at the last moment, revealing their UV-reflective tongues. One particularly amusing paragraph of the study suggests that the more intense attacks elicited a stronger tongue-response: the more risk the skinks felt exposed to, the more tongue they would poke at their enemies. I can relate to their fighting style.

Bluetongue display.

Northern Bluetongue skink performing a ‘full-tongue’ display in response to a simulated attack by a model predator. The face of a true warrior.
Image credits Peter Street / A. Badiane et al., 2018, Behavioral Ecology and Sociobiology.

“The lizards restrict the use of full-tongue displays to the final stages of a predation sequence when they are most at risk, and do so in concert with aggressive defensive behaviours that amplify the display, such as hissing or inflating their bodies,” explains lead author Arnaud Badiane.

“This type of display might be particularly effective against aerial predators, for which an interrupted attack would not be easily resumed due to loss of inertia.”

Finally, the team notes that tongue-displays were most often triggered by the fake bird and fox models, rather than by those of snakes or monitor lizards.

“The timing of their tongue display is crucial,” adds Badiane. “If performed too early, a display may break the lizard’s camouflage and attract unwanted attention by predators and increase predation risk. If performed too late, it may not deter predators.”

If you’re ever caught between a rock and a hard knuckle, stick your tongue out. It likely won’t be as effective as those of the skinks, but maybe you’ll confuse people enough to make your (brave and honorable) escape. Worth a shot.

The paper “Why blue tongue? A potential UV-based deimatic display in a lizard” has been published in the journal Behavioral Ecology and Sociobiology.