Squirrels, in theory, can survive a fall from an object of any height due to two factors: their size and their mass. A force (such as the force of gravity) is calculated by multiplying mass and acceleration. The acceleration due to gravity on Earth is always roughly 9.81 m/s2, regardless of what object it is acting on. Squirrels are not very heavy—a grey squirrel only weighs about 0.5 kg—meaning that the force acting on a falling squirrel just isn’t that big.
Force = mass*acceleration = 0.5 kg * 9.81 m/s2 = 4.9 N
We measure forces in a unit called “Newtons”, named for Isaac Newton who gave us Newton’s three laws of motion.
Compare this to, for example, a falling 60 kg human, which would be pulled downward with a force of about 489 N. A factor of 100 higher!
On top of being small, squirrels are fluffy and intuitively spread their bodies out when falling. This allows them to experience as much wind resistance as possible, slowing down their rate of descent. Some squirrels even use this fact to glide through the air. While gliding is not the same as flight, we nonetheless call them flying squirrels.
For these two reasons, the terminal velocity (fastest speed while falling) of squirrels is slow enough that they will, at least in principle, never fall so hard that they hurt themselves.
Every year upwards of 25 million birds are killed in Canada due to collisions with buildings, communication towers, wind turbines, and as a result of being tangled into marine gillnets. From window decals to flashing lights, humans have tried numerous preventative measures to stop these deaths. Their degree of success depends on the method, the location, and the types of birds in that ecosystem—amongst many other factors—and results are highly variable.
What may seem like benign interventions that—at worst—just won’t work, actually have the capacity to do harm. As an example, In Peru, bycatch (i.e., accidental catch) of Guanay Cormorants was reduced more than 80% after researchers attached green lights to gillnets. At the same time, bycatch of Peruvian Boobies increased. Possibly due to the boobie’s attraction to the lights.
Similarly, when researchers set out to the Baltic sea to compare the effects of attaching light panels, constant green lights, or flashing white lights to gillnets on sea birds (in particular the Long-tailed duck, a vulnerable species) they found that the nets with flashing white lights caught more ducks than the normal, non-illuminated ones.
Shots, jabs, pricks—whatever you call it, having a needle inserted into your body is not most people’s idea of a fun afternoon activity. Even if you don’t have a specific needle phobia, injection reactions typically range from neutral at best to quite negative at worst. But what if needles didn’t have to hurt? Or, at least, what if they hurt less? It seems intuitively true that decreasing the size of a needle would make it hurt less, but is it really that simple?
The diameter of a needle (how big it is across) is measured in a unit called a gauge. Because the concept of a gauge pre-dates the 18th century and has been defined in many different, inconsistent ways, it’s worth specifying that needle width is measured in the Birmingham gauge. The bigger the gauge, the smaller the needle. For example, the width of a 7-gauge needle is roughly 4.6 mm (0.18 inch), while the width of a 30-gauge needle is about 0.31 mm (0.012 inch). To give you some context, a typical spaghetti noodle is roughly 14-gauge, and a regular stud earring is about 19-gauge.
There are a few factors that determine what size of needle a practitioner needs to use, including the body size of the patient and the body part being pricked, but a critical factor is the amount of fluid being injected or drawn out of the patient. If you try to inject a large amount of fluid through a very thin needle, it will both take longer and hurt more due to the high pressure.
For blood collection, which is typically a few millilitres of blood, clinicians use needles of 21-22 gauge. Vaccines are often <1 mL and accordingly use needles that are slightly smaller, around 22-25 gauge. Delivering insulin to diabetic patients requires even less fluid and can use needles as small as 29-31 gauge.
Even with the limitations imposed by volume, there is some wiggle room in the gauge of needle used for a certain procedure. Medical practitioners can often use their own judgment, experience, and clinical guidelines to change the size of needle they use. Much like how artists may favour a certain size brush, some clinicians have personal preferences in the tools of their trade.
Luckily, it is actually relatively simple to study whether decreasing needle diameter decreases pain. Just find some volunteers who are willing to be stabbed for science (or who are already being treated with a needle-involved method), stick them with at least 2 needles of different gauges without telling them which is which, and ask them how much it hurt on a numeric scale. There are dozens of studies that take this form.
Regarding simple injections in the body, this study compared a 30-gauge needle with a 26-gauge one and found no significant difference in the reported pain. As did this study, which compared 27-gauge vs 23-gauge vs 21-gauge. For injecting Botox around patients’ eyes, this study found no difference in pain scores between a 32-gauge and a 30-gauge needle. These are by no means all of the studies on needle size and pain, but they are representative of the scientific literature on this topic. Again and again, trial participants seem to find no significant difference in their pain when comparing needle gauges.
For many people, the anesthetic injection is the worst part of any dentist visit. While it would be lovely to tell you that a quick swap to a thinner needle is all you need to decrease the pain of dental injections, there is a wealth of evidence to the contrary. For anesthetic injections in the mouth, smaller-width needles were not only ineffective at reducing pain; in one study, they actually increased it!
When non-native animals are introduced to an ecosystem, quite often, the very delicate balance of that environment is thrown off. Plants, animals, fungi, bacteria, and everything else in a biome are connected through the food web, meaning that small changes to any part of a habitat can have extensive consequences.
From zebra mussels in Canada to grey squirrels in the United Kingdom, invasive animals have become a massive problem with increases in global travel and shipping. We enact biosecurity laws and protocols, quarantine procedures and mandate pesticide treatments to try to limit their spread; but despite all our efforts to curb invasive invasions, there is one species that we tend to give a pass to: cats.
Domestic cats are not native to anywhere. While they are descended from Felis lybica, the African Wildcat, the domestic cat is a different species. They are even given a separate Latin species name: Felis catus.
Even when well fed at home, domestic cats often engage in predation and hunting behaviours. With some variance depending on location, cats tend to kill more birds and small mammals than anything else. Since domestic cats are an introduced species, they have tremendous potential to upset intricate ecological situations.
Some researchers strongly believe that domestic cats’ damaging influence on the environment has already been robustly demonstrated. They feel it is crucial to act immediately and decisively if we want to have any hope of counteracting the damage done by domestic felines. For example, in 2018, conservationists from Oklahoma State University and the Smithsonian Conservation Biology Institute published a paper wherein they denounced what they described as organised misinformation campaigns spreading junk science about domestic cats’ effects on ecosystems.
They invoke the Merchants of Doubt moniker—the name given to the “cabal of industry-beholden” contrarian scientists who denied evidence of harm by tobacco smoking, DDT and climate change for financial gain—and liken outdoor cat advocates to “cigarette and climate-change fact fighters” pushing “propaganda.”
Conversely, other researchers feel that many conservation scientists are fueling an unwarranted moral panic over outdoor cats with exaggerated claims and inadequate evidence. In response to the 2018 Merchants of Doubt publication, researchers from six universities around the world collaborated on a rebuttal. They wrote that:
equating the resources and power of global corporations and economic elites (e.g., Exxon Mobil) with the reach and advocacy of comparatively small non-profit organizations and university academics strains the [Merchants of Doubt simile] past the breaking point.
The authors take issue with conservationists concluding that cat advocates are acting with nefarious or bad faith motives and feel that calls for things such as “remov[ing cats] — once and for all — from the landscape” by “any means necessary” are sensationalist and premature. Instead, they call for better research to investigate the severity of the risks cats pose to habitats and the appropriate levels of interventions, and humane but effective alternatives to simply killing and banning outdoor cats.
A White-Hot Issue
If you’re not that familiar with the literary style research papers are usually written in, let me just say, it’s not usually quite like this. Usually, one side of an academic debate is not accusing the other of being corporate shills. The vast majority of the time, there are no mentions of “zombie apocalypse[s]” or calls to let things “weigh heavy on our shoulders.”
The rhetoric throughout the literature on outdoor cats is very inflammatory. The cats/birds issue isn’t just a problem to be solved. It is a fight; a conflict; a war. Solutions to this situation are needed urgently. Danger is imminent. “Drastic times call for drastic measures.” People “must ask themselves which animals should be saved but do so quickly because there is no time to [do both]… before extinctions occur”.
Clearly, the environmental impact of cats on birds, and the welfare of cats, are contentious and emotionally charged topics. It makes a lot of sense that they are. Environmental stewardship is an important role that humans are morally obligated to fulfill. Especially in the face of an existential threat. At the same time, cats also represent life that should be protected. Cats long ago transcended their status of just-another-animal. From their initial roles of pest control, they have become members of the family. Given as much, cat owners often take advice regarding their pets personally.
The thing is, this highly polarised landscape filled with provocative language and antagonistic interactions isn’t helping either side. And it isn’t helping the birds, or the cats, either.
Whether cats impact wildlife in a meaningful and long-lasting way is a question for the experts in this field. They do not seem to agree, which implies the need for more research on the matter. Either way, it doesn’t particularly matter who is “right” anymore.
What matters is how needlessly divided the debate has become.
A Birdy Binary
A false dichotomy has been created wherein one can either care about native wildlife or feline welfare, but never both. Either cats are the enemies — the representations of humans’ entitlement and disdain for the earth — or the most perfect companions, too often neglected and maligned, who are just following their natural instincts.
We do ourselves a massive disservice by reducing this complex and multifaceted issue to one side versus another, or ‘us versus them’. People are lumped into supposedly either loving birds and hating cats or vice-versa, when in truth, most conservationists and pet owners are motivated by similar loves of nature, flora, and fauna.
This artificial divide encourages more polarising solutions, more extreme takes and leads to fearmongering and moral panics. It not only creates this illusion of a lack of a middle ground, it eliminates any of the methods or solutions that would originate from there.
We can become so hyper-focused on advocating for one position that we become blinded to other parts of the issue. Habitat loss is displacing bird populations and climate change is affecting their ability to find food and water. As cities sprawl outward, they remove homelands for birds and disrupt migration routes. In Canada, around 100 million birds are estimated to die every year due to collisions with buildings, power lines and cars.
Such black-and-white thinking discourages the peer review process. With little room for nuance, any criticism of a study’s methods can be seen as dissent. Scientists need to feel free to question how research is performed and how it draws its conclusions without fear of being labelled as agents of misinformation.
It’s Getting Mean in Here
Outside of academic discussions, the binary division between perceived “bird lovers/cat haters” and “cat lovers/bird haters” is even wider. This pattern is seen to varying levels across social media, traditional media, and interpersonal relationships. Expressing the wrong opinion on Twitter about indoor/outdoor cats can lead to harassment and ostracisation.
We should all know that an anecdote is not good evidence for anything on its own. Nonetheless, let me tell you a short one.
I have written on a variety of “controversial” topics in the past — menstruation, copycat suicides, female ejaculation, transgender children, border walls — but only once have I been kicked out of a science-themed social media group. I was removed after sharing my (then) most recent article on whether bells on cat collars work to reduce the amount of prey that domestic cats kill. For the record, three studies (one published in 2005, one in 2006, and one in 2010) have shown that cats brought home less prey when they wore bells. But very quickly, the thread of responses devolved into name calling and insinuations of nefarious or financially motivated intentions.
Empathy works, not… whatever that is
What should be a logical debate on policies and practices has turned ugly. The cats and birds issue has become a hotbed for sensationalism and hyperbole, no matter your stance. And the worst part about it is that we know it won’t work as well as collaborative and kind approaches would.
We know that when trying to change somebody’s mind, what tends to work is empathy and ongoing dialogue. We want to avoid judgment, disdain, or anger. Scientists need to be transparent about how they draw their conclusions and accept legitimate criticisms. Science is not perfect or magic but just a tool to help us understand the world around us. Trust is crucial for effective communication of knowledge, and trust cannot be built on anything but honesty and openness.
Actually helping wildlife and domestic pets alike requires engaging with all stakeholders. Especially the ones that oppose your stance. As much as we may want to rant and kick and scream at the people who disagree with us, it’s pointless. Not only that, it’s actively detrimental to their understanding and your ability to communicate with them. Like with so many things, in science communication, kindness is key.
As Benjamin Franklin wrote in 1789, “In this world, nothing can be said to be certain, except death and taxes.” For everything else, there is an inherent degree of uncertainty. We don’t often come face to face with quantitative probabilities in our everyday life, save for one: probability of precipitation (PoP).
A seemingly simple concept, PoP is present in most of our daily routines as we check the weather before getting dressed. You may not explicitly realize it, but we all have personalized thresholds for the PoP at which we will choose to bring an umbrella or cancel an outing. For some, a 60 percent PoP warrants carrying an umbrella; for others, only 80 percent or higher. Unfortunately, most of us don’t have an accurate idea of what PoP truly means, even though most of us are certain we do!
A 60 percent PoP does not mean that 60 percent of an area will receive precipitation. It also does not mean that it will rain for 60 percent of the time period, and it does not mean that a forecaster is 60 percent confident that it will rain. So, what does it mean?
As defined by the National Weather Service, a probability of precipitation (PoP) is the “chance that at least 0.01 [inch] of rain will fall at the point for which that forecast is valid over the period of time given.”
So, a 60 percent PoP means that when these meteorological conditions occur in this area, 6 times out of 10, there will be at least some rain. That’s what PoP is. But how is it calculated?
PoP = Confidence x Coverage
To find the PoP for a given area over a given time period, we take the confidence of the forecaster and multiply it by the area that will be affected by the precipitation. Say I was 100 percent confident that 50 percent of Cleveland would receive at least 0.01″ of precipitation tomorrow, the PoP would be (1 * 0.5 = 0.5) 50 percent. Now, if I was only 80 percent confident in my prediction that 50 percent of Cleveland is getting wet tomorrow, the PoP would be (0.8 * 0.5 = 0.4) 40 percent!
If you stay in the same spot all day (like I did writing this article), then a 40 percent PoP means you have a 4 in 10 chance of being rained on. But, if you move around within an area, or between areas, your probability of encountering rain increases. As Brad Panovich, Chief Meteorologist at WCNC Charlotte put it, “It’s like buying more raffle tickets. Each one you buy increases your chances of winning.”
If you were mistaken about PoP until today, count yourself among good company. Weather forecasts have been available to the general public in the United States since the late 1960s, but in studies, between 35 percent and 73.8 percent of respondents defined PoP wrong, even when they were meteorologists! A viral Tik-Tok from 2019 that incorrectly taught people the untrue percent-of-land PoP definition certainly hasn’t helped things.
It turns out that even those sort of wishy-washy terms meteorologists use to describe weather such as “scattered flurries” or “isolated showers” have fairly strict definitions too. The National Weather Service uses certain expressions to communicate the degree of certainty in a forecast: “slight chance,” “chance,” and “likely.” There are also particular qualifiers to convey the portion of the area that will be affected: “isolated/few”; “widely scattered”; “scattered”; “numerous”; or “occasional/periods of.”
At least in Canada, the term “risk” as in a “risk of thunderstorms” indicates a 30–40 percent chance of said weather occurring. Fun fact, also in Canada, a PoP of 50 percent is never permitted, because it seems too indecisive.
So, to those who previously found themselves cursing the local weather forecaster for never getting it right, hopefully, this article helps explain that your own lack of knowledge was more likely at fault than theirs. Believe it or not, weather forecasts have actually been getting more and more accurate with time. In 1972, a National Weather Service forecast made three days before was off by an average of six degrees. Forty years later, it was down to three degrees. In the late 1980s, when trying to predict where hurricanes would make landfall three days in advance, the National Hurricane Center missed by an average of 350 miles. Now the average miss is only about 100 miles.
Now, that’s not to say that meteorologists can’t be biased. Many weather agencies previously biased their forecasting toward more precipitation than will actually occur. This so-called “wet bias” meant that for years when the Weather Channel predicted a 20 percent PoP, it actually rained only roughly 5 percent of the time. It’s unclear if the wet bias is still influencing forecasts today.
Take a look at the chart below. It shows the percent confidence on the top and the percent area on the side. By multiplying these together we get the PoP at the intersection of the two. The chart is symmetric. For example, if your confidence is 90 percent and the area affected is 50 percent, the PoP equals 45 percent. If the values were opposite, the PoP would still be 45 percent. This means that even though there are multiple ways to arrive at each PoP, in the end, they mean similar things.
A 40 percent PoP can be arrived at by multiplying 100 percent and 40 percent or 50 percent and 80 percent. Therefore, a 40 percent PoP could mean that it is:
Absolute certainty (100 percent) that some (40 percent) of the area will receive rain, or
Quite likely (80 percent) that half (50 percent) of the area will receive rain, or
Somewhat possible (40 percent) that all (100 percent) of the area will receive rain, or
Possible (50 percent) that most (80 percent) of the area will receive rain.
In the end, all these basically mean “you probably won’t need an umbrella, but it’s not a bad idea.”
Similarly, you’ll notice that to get a PoP of 70 percent or above, one of either the confidence or area must be greater than 70 percent. Regardless of whether that’s the result of being very sure it’ll rain over more than half the area, or being fairly sure it’ll rain over the entire area, what matters is that you remember to close your bedroom window.
Whether you’re buying ingredients for an at home “Coke and Mentos” demonstration, asking a flight attendant for a beverage, or just trying to pour a can of soda into a glass before hockey comes back on, you may have noticed something: Diet sugar-free sodas fizz more than regular sugar-rich sodas when opened.
The degree of carbonation or “fizziness” of a soda is partly a function of how easily carbon dioxide bubbles can form in the sugary flavour water we call pop. When it’s easier for bubbles to form, you get more of them and therefore an increased “fizziness”.
When a liquid has a high surface tension, it means that the bonds between the liquid’s molecules are very strong. Surface tension is why some spiders can walk on water—the spider’s weight isn’t enough to break apart the water molecules! In a substance with high surface tension, bubbles will not form very easily.
Surfactants are chemicals that decrease the surface tension of a liquid. They will therefore make it a bit easier for bubbles to form. Regarding Diet Coke, aspartame, and potassium benzoate (a preservative) are surfactants! Caffeine as well, but it has much less of an effect due to its low concentration.
Bubbles of gas will struggle to form in very viscous liquids, like maple syrup or waffle batter. Diet soda actually has a slightly higher viscosity than sugary soda, which slightly diminishes its fizzing potential. However, a slightly higher viscosity means that when bubbles do form, they’re a bit more stable. This explains why Diet Coke not only fizzes more than classic Coke, but the foam also lasts longer!
The Emerald Ash Borer (EAB) is a species of jewel beetle native to eastern Asia. In 2002, the beetle was detected for the first time in North America. First in Michigan, then Ontario, although tree ring analysis suggests that it has likely been present in those regions since the early 1990s. Since then, the number of EABs have increased year after year as the bugs spread across Ontario, Quebec and more than half the continental U.S.
An infection of EABs can kill an otherwise healthy ash in 2-5 years. But how can an 8.5 mm long insect kill a tree anyways? One way would be by eating all of its leaves. Without foliage, a tree has no way to photosynthesize, and therefore no way to make energy. Adult EABs do munch on leaves—a loss of tree canopy is a warning sign of EAB infestation—but not usually to the degree that would kill an ash. Instead, it’s the EAB larva that cause the majority of the damage.
EAB eggs are laid on ash branches, and larvae, once hatched, chomp their way under the bark. The little grubs will chew out 6 mm wide S-shaped tunnels called galleries to live in that can be up to 30 cm long. These galleries disrupt a tree’s internal water transport system, taking away its ability to send necessary nutrients up to its branches and leaves. As a result of nutrient deficiency, EAB-infected ash trees often show signs of chlorosis, or a lack of green colour in their uppermost leaves. Dying ash trees will sometimes send out epicormic shoots—little sprouts from the roots or lower trunk and branches—in an attempt to survive.
Most EABs spend winter inside ashes in their larval form. They’re able to withstand temperatures down to -30 ˚C, and are partially insulated by the tree bark. Eventually, come spring, the fully matured beetles will emerge from the ash trees, leaving small capital D-shaped exit holes about 4 mm wide.
The loss of one type of tree might not seem like such a cause for alarm, but the widespread death of ash trees is having many repercussions. In 2015, Montreal was home to roughly 200,000 ash trees. Mont Royal, the iconic park in the centre of the island was, until recently, home to over 10,000 of those trees. But, as a result of the EAB infestation the City of Montreal was forced to cut down about one-third of those ashes. The other two-thirds they chose to treat with preventative insecticides. To make up for the over 3000 lost trees, the city will plant 40,000 saplings. Of these, about 50% are expected to thrive. In 2016 Montreal committed $18 million to fighting the EAB and replacing the ashes it kills. In the U.S., affected states spend an average of $29.5 million per year to manage EAB populations.
The loss of ash trees can impede ecosystems, bring down home values or disrupt food webs. During bad weather, sick or dying ashes can pose a safety risk if they fall or drop branches. And with the loss of these trees comes an increased risk of landslides and flooding, both of which tree roots help to prevent.
A certain amount of the muddy colour can be attributed to the different colours of food we eat. Like mixing all the paint colours together, the result is a dull brown. But, much bigger factors for humans’ brown poop are bilirubin and bile. Bilirubin is a yellow substance found in the liver, the product of the breakdown of old red blood cells. Bile is dark brown or green and is produced by the liver to help digest fats. Both of these substances are secreted into the small intestine during digestion, and slowly make their way into poop, bringing with them a dark brown hue.
Bird poop, on the other hand, is not brown but white. That is because—unlike mammals—birds don’t pee!
How do fireflies create their telltale glow? It differs slightly depending on species—there are more than 2000 species of fireflies found across the world, including many that do not glow—but the one we know the most about is the North American Firefly (Photinus pyralis). It uses a molecule named luciferin and its enzyme buddy luciferase. Luciferase reacts with luciferin, causing it to break down into two compounds and release CO2 One of those two compounds has a bit of excess energy that it releases as light!
The production of this light has three requirements, other than luciferin and luciferase: magnesium, oxygen and ATP. That ATP requirement is a big part of why the luciferin assay has become an important tool for biochemical research. Adenosine-5′-triphosphate (ATP) is the universal “energy molecule” of all forms of life. So, luciferase and luciferin can be used to test if something like a cell is alive and still producing ATP.
One group of fireflies, however, use their glowing abdomens to hunt. Females of the genus Photurisengage in aggressive mimicry by imitating the flashing patterns of other species’ females to lure and eat the males who seek mates.
Unfortunately, due to habitat loss and climate change, firefly numbers are declining across much of the world. The lack of appropriate green spaces for fireflies to live and mate is compounded by the sedentary nature of many firefly species. The larvae of the common European glow-worm are reported to move only about 5 meters (16.4 feet) per hour. Light pollution as well may be impacting fireflies’ ability to thrive. In one study, light pollution reduced the flashing of Photuris versicolor by almost 70%.
As runners-up, the jury chose Emily Choy, a postdoctoral fellow who is doing research about the effects of climate change on seabirds in the Arctic, and Ada McVean, a master’s student who has an active and ongoing presence as a well-versed science communicator on the radio, on TV and on various social media platforms.