Charles Darwin postulated that Toucan’s massive beaks might be for sexual selection purposes. Other scientists have theorized that it could be for shows of intimidation, for actual defence or for peeling fruit. Given the beak’s serrated edge, it was once thought that toucans used it to catch and eat fish. We now know that toucans are almost entirely fructivorous, although they do opportunistically eat insects, lizards, and even small birds.
Another thing we now know is that the main function of a toucan’s beak is actually thermoregulation! Just like elephants do with their ears and dogs with their tongues, Toucans rely on their big beaks as heat sinks to maintain their homeostasis and save them from overheating.
Bird beaks across the globe follow a trend called Allen’s Rule, which proposes that the appendages of endotherms (warm-blooded animals) are smaller, relative to body size, in colder climates in order to reduce heat loss. A study of 214 bird species from every continent found strongly significant differences in their beak sizes according to latitude and local environmental temperatures. From penguins to parrots, the species that live in colder places have smaller peckers.
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.
If you’re not particularly salmon savvy you may be under the impression that “salmon” is an individual species of fish, like how a black bear is an individual species of bear. That, however, is not true of our fishy friends. In fact, there are two main divisions of salmon: Atlantic and Pacific.
Atlantic salmon are big fish found in the northern Atlantic Ocean weighing 8-12 pounds when fully grown. Their meat is known to taste very mild and is generally cheaper than other types of salmon, due to the fact that nearly all of the Atlantic salmon commercially available today is farmed.
Climate change, human colonization, habitat destruction, and overfishing have decimated the wild populations of Atlantic salmon that were once abundant throughout the northern Atlantic. Lake Ontario was once home to this fish, but by 1900 the population was completely extinct. While there are still wild Atlantic Salmon alive and swimming, their capture is strictly regulated, hence the need for fish farms to fill this void.
What about Pacific salmon? Well, its name is a misnomer, since there isn’t one species of fish called Pacific salmon, but rather seven different species of salmon who live in the pacific: Sockeye, Chinook, masu (found mainly near East Asia), pink, Coho and Chum. While the Pacific salmons have suffered population losses due to humans and climate change, their numbers haven’t been decimated to the extent of the Atlantic salmon, so, wild-caught Pacific salmons are still commercially available.
Chinook (also called King) salmon are the largest of the Pacific salmons, weighing between 20 and 135 pounds. They’re known for being fatty, making them of value to chefs, and also quite pricey, due to their general rarity amongst fish. If you’re after something a little cheaper but still fat-filled, the Coho might be for you. At roughly 20 pounds in size, it is often cooked whole. Your low-fat salmon options include the lesser-known Chum or pink salmons, both quite small and low in fat, as well as the well-known, medium-sized, and bright pink Sockeye.
Whichever type of salmon you choose to eat though, you’ll want to find out where it was caught and whether it was farm-raised or wild-caught. Not for culinary purposes, since at least one study found that farmed salmon was as acceptable to eaters as wild salmon, but rather for health ones.
Quiteafewstudieshaveexaminedthelevels of contaminants like PCBs (polychlorinated biphenyls), PBDEs (polybrominated diphenylethers), PAHs (polycyclic aromatic hydrocarbons) and mercury, and the results have not been confidence inspiring.
A 2001 study found that farmed salmon showed higher levels of PCBs, PBDEs, DLCs (dioxin-like compounds) and other chlorine-containing pesticides that pose significant health risks to humans. Similarly, a 2004 study found high levels of organochlorine contaminants in farmed fish and found that farmed salmon originating in Europe had much higher contaminant concentrations than salmon originating in North America or Chile.
The contaminants seem to get into the salmon through their food. Commercially available salmon feeds are extremely high in contaminants like PCBs and PBDEs, likely due to being made from small fish who themselves harbour high concentrations of contamination.
Interestingly enough, mercury, the contaminant we are used to hearing about in fish, is not an issue for either wild or farmed salmon. One study found that there’s less mercury in B.C. raised salmon than other foods like eggs, honey or vegetables.
Severalstudieshave found that as few as one meal per month of farmed Atlantic salmon can expose the eater to contaminant levels that exceed those set by governing bodies like the World Health Organization. To reach a similar level of contamination by eating wild-caught salmon alone would take more than 4-16 meals per month. You can see a representative chart of this data (based on the United States Environmental Protections Agency’s guidelines) below.
Fish farms can also have devastating environmental consequences due to antibiotic use, waste accumulation, disease spread, escaped fish and more. These effects are bad not only for the surrounding oceans but for the fish too. Infections like sea lice can cause fish extreme pain or even kill them, and the genetic disorders common in farmed fish like curved spines or malformed jaws can severely harm their welfare.
So, what does this all mean for those who feed on fish?
You should keep in mind the potential risks of eating farm-raised salmon while grocery shopping and remember that you can minimize your exposure to these contaminants by choosing salmon that is either wild-caught or farm-raised in North America whenever possible.
If you’re eating salmon mainly for the omega-3 fatty acids, I have some good news and some bad news. The good news is that there are several non-meat sources of omega-3s, such as flax, chia, and hemp seeds, flaxseed oil, and eggs. The bad news is that many of the supposed health benefits of omega-3s have been largely overblown. Our own Dr. Christopher Labos has writtenabout omega-3’s ineffectiveness in preventing cardiovascular events and quite a few Cochrane reviews have found no benefits from fish oil for many conditions including ulcerative colitis, asthma, Crohn’s disease, allergies in children and dementia.
Consider these pros and cons before attaching a bell to your cat’s collar.
Does your cat bring you dead animals? While this common behaviour is kind of yucky, it’s also sort of endearing – your cat is bringing you what she believes to be an excellent gift. But despite their generous intentions, hunting by domestic cats is affecting ecosystems and pushing some species to extinction. So what can you do to keep your cat from catching wildlife? There are two primary solutions to consider: keep her inside, or attach a deterrent (such as a bell) to her collar.
A closer look at the options
Of course, the easiest method of preventing your cat from killing birds and rodents is to keep her inside all the time. In the safety of your home, your feline’s exposure to prey animals will be limited to any mice that happen to get into your house. If you aren’t willing to curb your feline’s wanderlust, a common alternative is to attach a bell to her collar to alert wildlife of her approach. But is this a safe and effective option?
The pros and cons of bells
A number of studies have looked at whether or not bells help prey escape from cats, and the general consensus is yes! Bells on collars seem to reduce the amount of prey caught by about half, which could be enough to no longer pose a threat to ecosystems.
Effectiveness aside, many pet parents worry that a bell will hurt their cat’s ears. According to Veterinary PhD student Rachel Malakani, a collar bell will produce sound at about 50-60 dB, but studies have shown cats to be unaffected by sounds under 80 dB. While some cats with anxiety may not react well to the bell’s sound, it’s likely that the majority of cats simply won’t care.
Some owners worry that as well as alerting prey, a bell would also alert large predators to a cat’s presence. While this is possible, given most predator’s acute hearing, it’s unlikely that the relatively quiet noise of a bell would make the difference between your cat getting detected or not. If you live in an area where your cat is at risk of being attacked by large animals you should probably be keeping your cat indoors anyway, or at least supervise their outdoor activities. You can also invest in a cat enclosure, which will allow your feline to enjoy the fresh air safely!
If you’re unwilling to put a bell on your furry buddy, you do have another option – cat bibs. Sold under names like Birdsbesafe, these devices are brightly colored to alert potential prey to the cat’s presence before they can pounce. While your cat might look a bit silly wearing a rainbow bib, the scientific research on these products shows they reduce predation rates by roughly the same amount as bells. That said, the devices that rely on color to alert potential prey work much better on birds (who have very good color vision) than they do on small mammals (who generally have quite poor vision).
If you’re scared of attaching any collars or collar-mounted devices to your felines – you shouldn’t be. While fears that cats can become strangled or trapped by a collar caught on debris are common, actual adverse effects from collars are rare. One study looked at 107 veterinarian practices and found only one collar-related injury per every 2.3 years, with collar-related deaths being even rarer. You can mitigate your fears further by using a breakaway collar.
If your cat ventures outdoors, especially if you live in an area with endangered species, please do your part to aid conservation efforts by outfitting your kitty with an anti-hunting device.
It’s probably not news to anyone reading this that lead exposure is dangerous, but when most of us think of routes to lead exposure we think of leaded gasoline, paints, drinking water or pencils (although pencils do not, and never did, actually contain lead). But there is another means of exposure that’s causing significant issues for certain populations: lead bullets.
Bullets have traditionally been made from lead for several reasons. The metal is cheap and melts at only 327˚C (621˚F) meaning that it can easily be formed into bullets. It is also very dense, so that lead bullets pack a big punch, so to speak. But lead is also toxic.
After an animal is hunted, even if care is taken to remove the bullet from the carcass, lead contamination of the meat can still occur. Part of the problem comes from the fact that lead bullets often fragment into many small pieces that can disperse throughout the tissue. These lead fragments can then be consumed by the humans or pets who eat this meat.
Severalstudies have shown that when game is hunted, killed, processed and cooked in standard ways, higher-than-normal levels of lead are found in the meals. This lead contamination especially influences those who rely on game meat as their primary source of food, such as those in Greenland, or Indigenous Canadians, or those using food banks for whom donations from hunters are fairly common.
Even occasional game meat eaters, however, can be affected by lead contamination. Health Canada states that blood lead levels below 5 μg/dL are associated with adverse health effects. One study found that those eating one or fewer meals of gamebird shot with lead bullets per week showed blood lead levels of 7.5 μg/dL, and those eating gamebird meat daily showed blood lead levels of 17 μg/dL. But the effects of lead bullets don’t stop with humans.
As it’s fairly common for hunters to eviscerate their quarry in the field and leave behind the unwanted viscera, scavenging animals can feed upon the discarded remains of humans’ prey and ingest lead in the process. This can lead to many of the same symptoms as human lead exposure.
Another route for exposure is found in birds’ gizzards. To help break down their food birds swallow small rocks and store them in their gizzards. The problem is that to a bird a bullet looks a lot like a small rock.
One Italian study found that those who engaged in hunting showed a blood lead level almost double those who didn’t. This could be from the lead fumes that are released when guns are fired or from handling lead ammunition. The same study did not find any relationship between blood lead levels and consuming game meat, which could point to some regional differences in ammunition manufacturing, hunting or cooking styles influencing the amount of lead that makes it into a final dish of cooked game meat.
Lead exposure can also occur in humans that are shot with lead-based bullets, especially since bullets are sometimes left in a victim’s body, either due to lack of medical attention or complications that would arise from trying to remove them. In some cases, symptoms can occur many years after the gunshot wound. To remedy this, a combination of drugs to help eliminate lead from the body, chelation therapy and surgery to remove the bullet are used.
The good news is that non-lead bullets are becoming more popular. Several places have enacted lead munition bans, and one study showed that non-lead bullets were just as effective for hunting animals as lead bullets. Those who handle bullets in their jobs (such as police or military personnel) would benefit from a switch to non-lead-based munitions, but beyond environmental and health benefits, switching away from lead bullets would also have an economic benefit, as this study shows. As for what could be used instead of lead, there are a few options, the most popular of which seems to be copper, but the most interesting of which is definitely depleted uranium.
Malaria is an infectious disease caused by a single-celled parasite that multiplies in human red blood cells as well as in the intestines of the Anopheles mosquito, the insect that transmits the disease. Researchers believe that malaria coevolved with humans in Africa. For its spread across the world, we can blame colonialism.
It is thought that malaria began to travel out of Africa about 3 000 years ago, after which its spread was hastened by wars and the import of human labour. Sardinia is an island south of Italy that was conquered by Carthage in 502 BCE. Seeking to use the land for agriculture, the Carthaginians clear cut the trees and vegetation. These ecological changes allowed flooding to occur, creating standing water that attracted mosquitoes. To work the new farms, Carthage imported labourers from Northern Africa who brought malaria with them.
About 200 years later, the Roman empire took over Sardinia, allowing malaria to make the leap to Europe. By the 1400s, malaria was well established in France and England. As populations grew, agricultural demands led to low lands and swamps being drained, often poorly, and what happened in Sardinia was repeated.
Once colonies in North America and the Caribbean were established, many of Europe’s poor emigrated there, bringing malaria with them. The agricultural practices used in the U.S. to grow cotton and rice, combined with the overcrowding and horrid conditions that slaves faced resulted in epidemics of malaria that ravaged the Southern U.S.
Colonialism’s effects on malaria were not restricted to its spread, however. Even in areas where malaria was already present, colonial influence often worsened conditions and caused epidemics.
In the southern African country of Swaziland, malaria was common but nonfatal before colonial intervention. This was due to the immunity that can be acquired with repeated exposure. When colonists arrived, however, they removed Swazi inhabitants from their homelands, forcing them to move into lowlands with larger mosquito populations.
Taxes imposed on Swazis, drought conditions, and the exportation of Swazi crops led to famines that left the Swazi people vulnerable to malarial infection. Droughts would temporarily relieve infections but at the cost of losing acquired immunity. Famines forced many Swazis to travel to find work and food, but travelling labourers would lose their acquired immunities, leaving themselves vulnerable to infection upon their return.
President Donald Trump wants to “build a wall” between the U.S. and Mexico that, depending on your political allegiances, will either keep out dangerous undocumented immigrants or will serve little purpose outside of wasting taxpayers’ money.
One potential effect not receiving much media attention, however, would be felt by plants and animals local to the areas surrounding the border.
A continuous wall on the border between Texas and its southern neighbour will require 1840 km to be built in Texasalone. Estimates for the habitat loss are approximately 12-20 hectares (30-50 acres) per kilometre of wall.
Texas is at risk of losing up to 36 800 hectares (92 000 acres) of habitats, and that’s before even accounting for the roads that will be built to construct, maintain and monitor the wall, as will facilities like guard houses and tech hubs.
But at least the organisms outside of the building zone for the wall will be ok, right?
A wall at the U.S./Mexican border will cause something called habitat fragmentation. This occurs when something (usually either human constructions or geological events) separates what used to be a continuous ecosystem. Habitat fragmentation, in turn, causes population fragmentation, as animals become unable to travel to access the now separate ecosystem as they used to. This can have really severe effects on flora and fauna populations. If unable to travel to find mates, animal populations become inbred and unhealthy and can die out entirely.
Some plants and animals can adapt to new habitats, or live in slightly different ones, but others have specific needs only met by specific habitats. It’s possible for ecosystems to be completely eliminated by a construction like the wall, or for animals to become separated from the habitat they need to live in. Take for example the Tamaulipan thornscrub ecosystem, found near Southern Texas rivers. Agriculture and city expansions have already eliminated much of this ecosystem, and the remaining sites are directly in the wall’s planned path. With the elimination of this ecosystem will likely come the extinction of the endangered wildflower Physaria thamnophila.
The loss of one obscure wildflower may not seem like a big deal, but there are many more organisms potentially at-risk including ocelots, whiskerbushes, pygmy owls, desert bighorn sheep, jaguars, Sonoran pronghorns and javelinas.
Despite this, the construction is able to occur unhindered by environmental protections due to the REAL ID Act of 2005 that allows the secretary of Homeland Security to waive laws such as the Endangered Species Act and the Migratory Bird Treaty Act.
It’s hard to know for certain the effects a border wall would have on ecosystems, in part due to the difficulty in studying these areas. Researchers have reported being detained and harassed by Homeland Securityand “Minutemen civilian militias”while attempting to conduct fieldwork. However, one 2014 studyexamined an area in Arizona with border barriers and concluded that while they did affect native species, they had no effect on the movement of people across the border.
Don’t just take my word for it though. A reportdetailing the devastating environmental impacts of a border wall was published in the journal BioScience, signed by 2556 scientists from 43 countries. I think it’s fair to say that science has reached a consensus, and they’re not pro wall.