Death by Rail: What We’re Finally Learning About Preventing Wildlife-Train Collisions
By Tara Lohan
Last year a terrible accident in India made headlines around the world. Late one February night, a speeding train struck a herd of elephants crossing the tracks, instantly killing two adults and two calves. A third adult died soon after.
It wasn't an isolated incident. Over the past 30 years train collisions have killed more than 220 elephants in India alone.
Most of those incidents don't generate international headlines; nor do the deaths of thousands of additional animals killed by trains worldwide each year. In fact most wildlife-train collisions go unnoticed, their fatalities left uncounted — which has made it difficult for experts to study the problem and mitigate its impacts.
That puts us woefully behind similar research to reduce vehicle-wildlife collisions on roads, an active field of research for the past two decades. That's because car-animal collisions present a greater danger to human safety and property, according to a 2016 study surveying the emerging field of railway ecology. "Despite the field of road ecology rapidly expanding and the large footprint created by railways, there is a prominent lack of research related to railways and their effects on wildlife," the study found.
Here's what we do know: Like roads, railways fragment habitat and can affect all kinds of wildlife in varying ways. Collisions are the most common cause of mortality, but some animals die from electrocution or being stuck between the rails, leaving them susceptible to predation, starvation or dehydration.
Exactly how many animals die is a bit of a mystery. Railway mortalities are usually not as visible to the public as roadkill, and railways can be harder to access for research and data collection, the 2016 study found.
The little research that has been done on railways and wildlife has been largely limited in both scope and geography. The majority of studies have looked at large mammals, mostly in North America and Europe, with some attention paid to elephant strikes in India.
"The mammal species receiving the most attention are frequently the larger ones, such as moose, bears or elephants as they cause more damage to trains, disrupt the normal operation of the train network, or hold higher conservation and economic status," according to the editors of the 2017 book Railway Ecology.
Understanding how to curb wildlife deaths from trains means first understanding what draws animals to the tracks in the first place, which is not always easy. New research is working to close that knowledge gap, identify problem areas and find cost-effective solutions.
Deer on the railway tracks in New York
Photo by Timothy Vogel, CC BY-NC 2.0
The timing of this research, experts tell us, is important. With rail transit of products and materials on the rise and high-speed rail networks expected to grow as we work globally to lower our carbon footprint, the number of fatalities could soon increase unless we devote more resources to additional research and mitigation.
Rail tracks can make for tough times if you're a toad — even a big one.
In Brazil a 2018 study found an estimated 10,000 Cururu toads (Rhinella marina) and related species, often called giant toads, were dying every year along a 500-mile stretch of railway. Researcher Rubem Dornas says they still don't know exactly why so many toads die, but it appears the tracks formed a barrier the toads can't cross while migrating. Despite the large size of the toads, which average about 4 to 6 inches in length, the researchers found they may not be able to jump or climb over rails more than 6 inches high.
"We think the main problem is the barrier effect caused by the rails," said Dornas.
Not all the fatalities are the result of being run over by passing trains. Some of the toads appeared to have died from desiccation due to extreme heat from the tracks.
Most horrifyingly, others showed signs of barotrauma, where a sudden change in air pressure from the fast-moving train causes the inner organs to be blown out — the toads literally exploded from the inside.
While additional research would help to better understand the problem and its population-level impacts for the toads, Dornas says that providing passage underneath the rails could be a useful solution.
A 2018 study of endangered gopher tortoises (Gopherus polyphemus), which have been known to cross railways near the John F. Kennedy Space Center in Florida, came to a similar conclusion.
"We predict that nearly all tortoises in the vicinity of railways are susceptible to becoming entrapped or experiencing reduced movement and dispersal," the researchers wrote. They recommended trenches that can create a safe passage underneath the tracks and an escape route for those that get caught between rails.
While smaller in size, these trenches are similar in concept to corridor bridges and tunnels that are commonly used to help animals safely cross roadways. And while crossing structures may be used occasionally for railways — like a "landscape" bridge over railway tracks that was opened in Stockholm, Sweden in 2017 — it's far less common. The biggest reason is simply financial — the structures take resources to build, and so far more investments have been devoted to reducing wildlife collisions on roads than rails.
Wildlife overpasses, like this one in British Columbia, are more common for roads than rails.
Photo by B.C. Ministry of Transport, CC BY-NC-ND 2.0
That could change with more interest in railway ecology and cheaper building options. ARC Solutions, a project of the Center for Large Landscape Conservation, held a recent design competition to rethink the materials and engineering used in wildlife overpasses to make them more sustainable and affordable. If those concepts come to fruition, it could mean an easier lift to develop safer crossing systems for all kinds of wildlife over both roads and rails.
Getting animals over or under tracks safely is helpful when a railway is an obstacle. But, as researchers found in Alberta, Canada, railways can also be a destination. And that requires a new set of solutions.
Concern over grizzly bear (Ursus arctos) deaths on the Canadian Pacific Railway between Banff and Yoho national parks has prompted years of study. "The causes for attraction of bears to the rail are really surprisingly complex and variable among individuals," said Colleen Cassady St. Clair, a professor of biological sciences at the University of Alberta, who has been leading a team to determine why grizzlies end up on railways and how to prevent their deaths. "There just isn't a single simple solution."
The biggest reason is that railways are a good place for a bear to find food. For one thing, the trains can spill grain from their cargo cars, leaving behind a steady supply of free food.
The very existence of the railways also opens up avenues for grizzly dining. The carcasses of deer and other ungulates struck by trains are an attractant for bears. Railways are slightly warmer than adjacent forests, which attracts ants, another grizzly food, researchers have found. And palatable vegetation also grows along the tracks, providing grizzlies with a wide range of edible choices.
This "edge habitat," according to a 2017 study co-authored by St. Clair, has "higher species richness, diversity and cover for seven of the eight most commonly-occurring species that are consumed by grizzly bears." Buffaloberry, a local fruit that's an important source of nutrients for bears pre-hibernation, was even found to have more fruit, ripen earlier and have higher sugar content within 15 meters of the railway lines compared to the nearby interior forest.
Food that grizzly bears like, including berries, has been found to grow more abundantly near rail tracks.
Photo by Christian Tauber, CC BY-NC-ND 2.0
More food along railways means the possibility of more train strikes on bears. So what to do about it?
One tactic would be to limit the growth of vegetation that attracts bears and other wildlife, or, as Canadian Pacific Railways has done, remove vegetation from along the tracks that could obscure sight and sounds lines to make approaching trains easier to see and hear at certain problem locations.
But St. Clair favors a different approach, developed by one of her graduate researchers, Jonathan Backs. He invented a warning system using a vibration sensor on the track that, farther down, triggers a ringing bell sound and flashing light 30 seconds before a train passes by a hotspot that has been designated for mitigation.
Acoustic warning systems have been developed elsewhere. Poland is testing a system that deters wildlife from approaching trains by loudly broadcasting recordings of barking dogs and alarm calls of other animals. Japan is testing a similar system. St. Clair says that these acoustic warning systems are promising, but it's too early to determine how effective they'll ultimately be. One drawback could be that if predator sounds are used as a deterrent and no predator ultimately appears, animals will stop associating those warning sounds with a risk.
To avoid that potential pitfall, the warning system that Backs is developing in Alberta has a key difference: It's not meant to scare the animals, but to teach them.
"Our idea with this approach was to help the animals learn that these warning signals, which are not scary in themselves, are reliably associated with the train coming, which most animals seem to find scary," said Backs. "And then the animals would learn to get out of the way when they receive these warning signals rather than waiting for the train to arrive."
Backs says he's still analyzing the data he has collected from trials of the warning system, but preliminary results are encouraging — and not just for bears. Other large animals appear to leave the tracks around six seconds earlier when the system is used.
And that's another reason St. Clair is excited about the potential of this system. Public interest in grizzlies helped spur the research, but the mitigation can be useful for all kinds of wildlife and all over the world. "The principles potentially apply to all animals," she said.
Backs says there is still more work to do to prove the concept and then find partner organizations to implement it. "The most important thing for me is to get it out there and make it real and put it in the hands of people who are working hard to keep animals safe," he said. "It might end up being only one part of a broader toolbox — different solutions are appropriate in different situations — but it's exciting that this could actually be used to save lives."
And for the field of railway ecology, more research is still needed, too, says St. Clair.
"We need a broader understanding of where mortality is a real problem, for which species and what the circumstances are that generate locations of higher vulnerability," she said. "Some ongoing work in Banff is trying to put together an entire database of animals that have been killed on the rail and determine what environmental and train operational factors seem to contribute to that vulnerability. With that information it will be possible to be more surgical, if you will, in applying the right kind of mitigation."
How Animals Benefit From Wildlife Corridors - EcoWatch: Quite interesting.Submitted by Christeen A to Offbeat | Note-it! |… @environmentguru— Environment Guru (@Environment Guru)1552396340.0
Reposted with permission from our media associate The Revelator.
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By Ana Maldonado-Contreras
- Your gut is home to trillions of bacteria that are vital for keeping you healthy.
- Some of these microbes help to regulate the immune system.
- New research, which has not yet been peer-reviewed, shows the presence of certain bacteria in the gut may reveal which people are more vulnerable to a more severe case of COVID-19.
You may not know it, but you have an army of microbes living inside of you that are essential for fighting off threats, including the virus that causes COVID-19.
How Do Resident Bacteria Keep You Healthy?<p>Our immune defense is part of a complex biological response against harmful pathogens, such as viruses or bacteria. However, because our bodies are inhabited by trillions of mostly beneficial bacteria, virus and fungi, activation of our immune response is tightly regulated to distinguish between harmful and helpful microbes.</p><p>Our bacteria are spectacular companions diligently helping prime our immune system defenses to combat infections. A seminal study found that mice treated with antibiotics that eliminate bacteria in the gut exhibited an impaired immune response. These animals had low counts of virus-fighting white blood cells, weak antibody responses and poor production of a protein that is vital for <a href="https://doi.org/10.1073/pnas.1019378108" target="_blank">combating viral infection and modulating the immune response</a>.</p><p><a href="https://doi.org/10.1371/journal.pone.0184976" target="_blank" rel="noopener noreferrer">In another study</a>, mice were fed <em>Lactobacillus</em> bacteria, commonly used as probiotic in fermented food. These microbes reduced the severity of influenza infection. The <em>Lactobacillus</em>-treated mice did not lose weight and had only mild lung damage compared with untreated mice. Similarly, others have found that treatment of mice with <em>Lactobacillus</em> protects against different <a href="https://doi.org/10.1038/srep04638" target="_blank" rel="noopener noreferrer">subtypes of</a> <a href="https://doi.org/10.1038/s41598-017-17487-8" target="_blank" rel="noopener noreferrer">influenza</a> <a href="https://doi.org/10.1371/journal.ppat.1008072" target="_blank" rel="noopener noreferrer">virus</a> and human respiratory syncytial virus – the <a href="https://doi.org/10.1038/s41598-019-39602-7" target="_blank" rel="noopener noreferrer">major cause of viral bronchiolitis and pneumonia in children</a>.</p>
Chronic Disease and Microbes<p>Patients with chronic illnesses including Type 2 diabetes, obesity and cardiovascular disease exhibit a hyperactive immune system that fails to recognize a harmless stimulus and is linked to an altered gut microbiome.</p><p>In these chronic diseases, the gut microbiome lacks bacteria that activate <a href="https://doi.org/10.1126/science.1198469" target="_blank" rel="noopener noreferrer">immune cells</a> that block the response against harmless bacteria in our guts. Such alteration of the gut microbiome is also observed in <a href="https://doi.org/10.1073/pnas.1002601107" target="_blank" rel="noopener noreferrer">babies delivered by cesarean section</a>, individuals consuming a poor <a href="https://doi.org/10.1038/nature12820" target="_blank" rel="noopener noreferrer">diet</a> and the <a href="https://doi.org/10.1038/nature11053" target="_blank" rel="noopener noreferrer">elderly</a>.</p><p>In the U.S., 117 million individuals – about half the adult population – <a href="https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/" target="_blank" rel="noopener noreferrer">suffer from Type 2 diabetes, obesity, cardiovascular disease or a combination of them</a>. That suggests that half of American adults carry a faulty microbiome army.</p><p>Research in my laboratory focuses on identifying gut bacteria that are critical for creating a balanced immune system, which fights life-threatening bacterial and viral infections, while tolerating the beneficial bacteria in and on us.</p><p>Given that diet affects the diversity of bacteria in the gut, <a href="https://www.umassmed.edu/nutrition/melody-trial-info/" target="_blank" rel="noopener noreferrer">my lab studies show how diet can be used</a> as a therapy for chronic diseases. Using different foods, people can shift their gut microbiome to one that boosts a healthy immune response.</p><p>A fraction of patients infected with SARS-CoV-2, the virus that causes COVID-19 disease, develop severe complications that require hospitalization in intensive care units. What do many of those patients have in common? <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6912e2.htm" target="_blank" rel="noopener noreferrer">Old age</a> and chronic diet-related diseases like obesity, Type 2 diabetes and cardiovascular disease.</p><p><a href="http://doi.org/10.1016/j.jada.2008.12.019" target="_blank" rel="noopener noreferrer">Black and Latinx people are disproportionately affected by obesity, Type 2 diabetes and cardiovascular disease</a>, all of which are linked to poor nutrition. Thus, it is not a coincidence that <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6933e1.htm" target="_blank" rel="noopener noreferrer">these groups have suffered more deaths from COVID-19</a> compared with whites. This is the case not only in the U.S. but also <a href="https://www.washingtonpost.com/world/europe/blacks-in-britain-are-four-times-as-likely-to-die-of-coronavirus-as-whites-data-show/2020/05/07/2dc76710-9067-11ea-9322-a29e75effc93_story.html" target="_blank" rel="noopener noreferrer">in Britain</a>.</p>
Discovering Microbes That Predict COVID-19 Severity<p>The COVID-19 pandemic has inspired me to shift my research and explore the role of the gut microbiome in the overly aggressive immune response against SARS-CoV-2 infection.</p><p>My colleagues and I have hypothesized that critically ill SARS-CoV-2 patients with conditions like obesity, Type 2 diabetes and cardiovascular disease exhibit an altered gut microbiome that aggravates <a href="https://theconversation.com/exercise-may-help-reduce-risk-of-deadly-covid-19-complication-ards-136922" target="_blank" rel="noopener noreferrer">acute respiratory distress syndrome</a>.</p><p>Acute respiratory distress syndrome, a life-threatening lung injury, in SARS-CoV-2 patients is thought to develop from a <a href="http://doi.org/10.1016/j.cytogfr.2020.05.003" target="_blank" rel="noopener noreferrer">fatal overreaction of the immune response</a> called a <a href="https://theconversation.com/blocking-the-deadly-cytokine-storm-is-a-vital-weapon-for-treating-covid-19-137690" target="_blank" rel="noopener noreferrer">cytokine storm</a> <a href="http://doi.org/10.1016/S2213-2600(20)30216-2" target="_blank" rel="noopener noreferrer">that causes an uncontrolled flood</a> <a href="http://doi.org/10.1016/S2213-2600(20)30216-2" target="_blank" rel="noopener noreferrer">of immune cells into the lungs</a>. In these patients, their own uncontrolled inflammatory immune response, rather than the virus itself, causes the <a href="http://doi.org/10.1007/s00134-020-05991-x" target="_blank" rel="noopener noreferrer">severe lung injury and multiorgan failures</a> that lead to death.</p><p>Several studies <a href="https://doi.org/10.1016/j.trsl.2020.08.004" target="_blank" rel="noopener noreferrer">described in one recent review</a> have identified an altered gut microbiome in patients with COVID-19. However, identification of specific bacteria within the microbiome that could predict COVID-19 severity is lacking.</p><p>To address this question, my colleagues and I recruited COVID-19 hospitalized patients with severe and moderate symptoms. We collected stool and saliva samples to determine whether bacteria within the gut and oral microbiome could predict COVID-19 severity. The identification of microbiome markers that can predict the clinical outcomes of COVID-19 disease is key to help prioritize patients needing urgent treatment.</p><p><a href="https://doi.org/10.1101/2021.01.05.20249061" target="_blank" rel="noopener noreferrer">We demonstrated</a>, in a paper which has not yet been peer reviewed, that the composition of the gut microbiome is the strongest predictor of COVID-19 severity compared to patient's clinical characteristics commonly used to do so. Specifically, we identified that the presence of a bacterium in the stool – called <em>Enterococcus faecalis</em>– was a robust predictor of COVID-19 severity. Not surprisingly, <em>Enterococcus faecalis</em> has been associated with <a href="https://doi.org/10.1053/j.gastro.2011.05.035" target="_blank" rel="noopener noreferrer">chronic</a> <a href="https://doi.org/10.1016/S0002-9440(10)61172-8" target="_blank" rel="noopener noreferrer">inflammation</a>.</p><p><em>Enterococcus faecalis</em> collected from feces can be grown outside of the body in clinical laboratories. Thus, an <em>E. faecalis</em> test might be a cost-effective, rapid and relatively easy way to identify patients who are likely to require more supportive care and therapeutic interventions to improve their chances of survival.</p><p>But it is not yet clear from our research what is the contribution of the altered microbiome in the immune response to SARS-CoV-2 infection. A recent study has shown that <a href="https://doi.org/10.1101/2020.12.11.416180" target="_blank" rel="noopener noreferrer">SARS-CoV-2 infection triggers an imbalance in immune cells</a> called <a href="https://doi.org/10.1111/imr.12170" target="_blank" rel="noopener noreferrer">T regulatory cells that are critical to immune balance</a>.</p><p>Bacteria from the gut microbiome are responsible for the <a href="https://doi.org/10.7554/eLife.30916.001" target="_blank" rel="noopener noreferrer">proper activation</a> <a href="https://doi.org/10.1126/science.1198469" target="_blank" rel="noopener noreferrer">of those T-regulatory</a> <a href="https://doi.org/10.1038/nri.2016.36" target="_blank" rel="noopener noreferrer">cells</a>. Thus, researchers like me need to take repeated patient stool, saliva and blood samples over a longer time frame to learn how the altered microbiome observed in COVID-19 patients can modulate COVID-19 disease severity, perhaps by altering the development of the T-regulatory cells.</p><p>As a Latina scientist investigating interactions between diet, microbiome and immunity, I must stress the importance of better policies to improve access to healthy foods, which lead to a healthier microbiome. It is also important to design culturally sensitive dietary interventions for Black and Latinx communities. While a good-quality diet might not prevent SARS-CoV-2 infection, it can treat the underlying conditions related to its severity.</p><p><em><a href="https://theconversation.com/profiles/ana-maldonado-contreras-1152969" target="_blank">Ana Maldonado-Contreras</a> is an assistant professor of Microbiology and Physiological Systems at the University of Massachusetts Medical School.</em></p><p><em>Disclosure statement: Ana Maldonado-Contreras receives funding from The Helmsley Charitable Trust and her work has been supported by the American Gastroenterological Association. She received The Charles A. King Trust Postdoctoral Research Fellowship. She is also member of the Diversity Committee of the American Gastroenterological Association.</em></p><p><em style="">Reposted with permission from <a href="https://theconversation.com/a-healthy-microbiome-builds-a-strong-immune-system-that-could-help-defeat-covid-19-145668" target="_blank" rel="noopener noreferrer" style="">The Conversation</a>. </em></p>
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