Du 14 au 19 août 2022 avait lieu la rencontre annuelle de l’Ecological Society of America (ESA), à Montréal. Une occasion en or pour découvrir l’ampleur de la recherche qui se fait en écologie actuellement. L’écoute des multiples présentations allant de l’écologie comportementale, à l’aménagement urbain soucieux des enjeux environnementaux et aux techniques de télédétection était très enrichissante.
L’obtention du prix d’excellence du CSBQ m’a permis de participer à cette conférence rassemblant des chercheurs internationaux et d’acquérir une expérience inégalée en communication scientifique. Effectivement, en plus d’écouter plusieurs présentations, j’ai eu l’occasion d’y présenter mes travaux de recherche effectués sous la direction de Monique Poulin et la codirection de Stéphanie Pellerin et Jérôme Cimon-Morin.
Ma participation à la conférence de l’ESA m’a permis de présenter les résultats de la recherche effectuée au cours de ma maîtrise portant sur les insectes pollinisateurs en milieux anthropisés. Les milieux agricoles et urbains sont en constant changement pour s’adapter aux variations démographiques. La planification de leur développement doit considérer les opportunités pour le maintien des services écologiques et de la biodiversité. Toutefois, une planification consciencieuse tenant compte de ces enjeux est tributaire des connaissances sur l’impact du développement agricole et urbain et de l’entretien des espaces verts qui les composent. Les études passées ont montré beaucoup de variabilité quant aux répercussions du développement des villes et de leurs périphéries sur les pollinisateurs. Également, ces études se sont intéressées plus particulièrement aux abeilles sauvages limitant les ressources disponibles pour planifier le développement du territoire pour les communautés de pollinisateurs plus largement. Ainsi, l’objectif de mon projet est d’éclaircir ces répercussions en évaluant la répartition et la diversité des espèces d’abeilles, de guêpes et de syrphes au sein de gazons et de prairies semi-naturelles en paysages agricoles, résidentiels et industriels. Pour ce faire, 18 gazons et 18 prairies semi- naturelles répartis uniformément entre les paysages agricoles, résidentiels et industriels de l’Agglomération de Québec ont été échantillonnés pour évaluer l’abondance, la richesse et la composition des pollinisateurs.
Moi c’est Sabrina Cloutier, je suis étudiante au doctorat en écologie forestière. Passionnée par les insectes, c’est ce qui a orienté mes travaux de recherche vers l’entomologie et, plus particulièrement, sur les pollinisateurs durant ma maîtrise. C’ est l’impact des paysages anthropisés et de l’aménagement des espaces verts sur les abeilles, les guêpes et les syrphes étudié sous la direction de Monique Poulin et la codirection de Jérôme Cimon-Morin et de Stéphanie Pellerin que je vous présente ici.
The purple martin swallows returned again this year. One of the last populations left in Quebec nests nearby. They occupy only a fraction of the nest boxes they once did, but they cling on.
They arrived right on time this year, but the bugs didn’t. It was cold, and the skies were empty of sustenance for an aerial insectivore.
Each spring I await heartbreak: one of these years, they won’t return. The clouds of insects that once brought them north to nourish their young are gone. Our dislike of insects has likely starved them and their songbird brethren. These astonishing aerial acrobats with their iridescent plumage and fluting cry have declined by 90% in their North American range. It seems only a matter of time before the lighthouse where they nest stands empty, a warning to us all of the cost of our comfort.
It is like this all over the planet.
Spring, which formerly was a time of great joy for anyone interested in the blooming of the natural world, has become fraught. As the air warms and the water thaws, I begin an anxious census: have they returned?
Much has been written about the restful benefits of communing with nature in this isolating time. But for naturalists, nature has become a battleground strewn with the ghostly outlines of the bodies of the missing.
Depressed Biologists Syndrome
I have an image in my head. It is a line drawing of a biologist in a sunhat, slumped in a corner, clutching a net, as the last butterfly, moth, insect or bird, the object of a lifetime of study, flutters to the ground before them.
It is a rough time to be a naturalist. Their mood is sliding downward in parallel with the trend lines on their species abundance data. I call it DBS: Depressed Biologists Syndrome. Watching a beloved species dwindle is like trying to carry a leaking bag. Biologists are facing the possibility that they will be obliged to seek work in different fields in the future. “Certainly , I often feel angry, frustrated and helpless about a great many conservation issues,” says Kyle Elliott, professor of avian ecology at McGill University.
But you can fight back.
Kristen Lalla is a surprisingly upbeat McGill student who studies the migration patterns of purple martins. But she has a problem: there are almost no birds left to study. If you are down to your last colony, you are not likely to let someone interfere with your birds, no matter how vital their research.
That hasn’t stopped Lalla: “Knowing that purple martins were in decline was one of the motivating reasons behind taking on this project. I was compelled to try and understand some of the knowledge gaps that may allow for better conservation planning. Feeling like I could possibly make a difference for this species motivates me to continue.”
The tyranny of small decisions leads to death by a thousand cuts
Urban life is so isolated from the nature that supports us that we often do not recognize what has already been lost, and what is threatened. It is evident if you look for it: twenty years ago I would need to stop every hour to clean my motorbike visor of insects. Now I can travel from Montreal to Toronto with scarcely a single bug sacrificed to my windshield. In the several years my daughter has played soccer, the insects that used to cloud the giant lights during evening games have now vanished.
Urban parks have low biodiversity, and are often overtaken by invasive species. The ash, elm and chestnut trees that used to grace our streets have been lost to exotic pests. Dog-strangling vine, an invasive milkweed, is wiping out the native version in Ontario. This is further endangering the beleaguered monarch butterfly, whose caterpillars rely on native milkweeds for food. Brides pose in front of tangled infestations of the vine in Toronto parks.
“Everyone is reading the ‘big’ headlines about declining species or wildfires in the Amazon,” asserts Elliott, “but know little about their own backyard. Local habitat issues in Quebec or Canada are seldom in the news…we are losing the local sources of information that are so critical to making important decisions. We need to become more involved locally, and invest in local news, local politics and what is happening near to us.”
It is on the margins, where the frog pond is lost to a housing development, that these changes are more apparent to anyone not in the business of counting wildlife. Quebec is conducting aerial spraying against spruce budworm, a native pest that cycles through outbreaks. That means killing all species of caterpillar that eat the sprayed leaves in a forest. Entomologists say the moths never recovered the last time this occurred. But losing the shelter of the trees will further endanger the few remaining southern caribou (and the logging industry). Yet there was little public reaction to the project.
Areas with industrial agriculture have become dead zones. Even the puddles near fields were found to contain dangerous insecticide levels1, and birds are not as successful nesting nearby. Ironically, urban areas are becoming refugia for some species2.
Losing their insect food sources is starving birds, and our desire for tidy lawns and lakeshores is destroying nesting areas. “I feel like the general public doesn’t know a lot about the purple martin’s situation,” says Lalla. “I think the education system should teach kids more about local wildlife. If more people knew about the problem, they would care more.”
We will always have wasps
You don’t need a degree in biology to lobby political leaders or upload species sightings. So maybe we should fight harder to save what we can, and revel in what we have. While insects such as butterflies and beetles avoid urban environments, wasps and ants do better there than elsewhere2. We will have to learn to love the ant, gull and squirrel.
We are told such species are a lot like us: adaptable and opportunistic. Such qualities may come in handy to counter the vicissitudes of conservation: insect populations, for example, fluctuate wildly. Monarch butterfly numbers returning to their winter refuge in Mexico in 2018 doubled. But only about half as many returned to the forest last winter. Something happened along the way. Then two forest rangers were murdered in the refuge, presumably over attempts to stop illegal logging of the trees upon which the butterflies roost.
It isn’t going to be easy to keep the needed army of volunteers motivated if their species disappears, but many are willing to try. “Knowing that a species isn’t doing well,” says Lalla, “drives a lot of people to do conservation work, I think. If a species isn’t extinct, there’s still hope, so we need to do something while we still can.”
All over the world, citizen scientists, such as Betty McCulloch (above), tag butterflies, count frog calls, or record bird sightings in a myriad of contributions scientists now rely upon for their data. “At this point,” says Lalla, who eventually located some subjects to study, “I’m cautiously optimistic. I know a lot of great people who are working on purple martins and other aerial insectivores, and so I hope that all this new information will lead to action.”
The martin decline has stabilized recently, due in part to the intensive work of nest box owners, says Elliott. “I find solace in the many friends and colleagues that are working to solve these issues. I hope that we can one day have purple martins in people’s backyards across southern Quebec.”
I too am motivated by hope: the weather has warmed, the caddisflies are hatching, and the martins turn and dive above the water. The first black swallowtail butterfly has wafted into my garden. The monarchs are one warm wind behind.
I have a dream that the sky above Montreal glows orange each fall with monarch butterflies rising and turning to head south, connecting us in a thousand-mile chain to Mexican mountains where no park rangers are murdered because everyone is watching.
I hope.
Marian MacNair created a phenology calendar for McGilll University’s Morgan Arboretum listing events as they happen during a year in nature. You can read more about her adventures chasing butterflies for her thesis on monarch preferences in Canada on her blog.
References
1, Samson-Robert O, Labrie G, Chagnon M, Fournier V (2014) Neonicotinoid-Contaminated Puddles of Water Represent a Risk of Intoxication for Honey Bees. PLoS ONE 9(12): e108443. https://doi.org/10.1371/journal.pone.0108443
2, Theodorou, P., Radzevičiūtė, R., Lentendu, G., et al, (2020). Urban areas as hotspots for bees and pollination but not a panacea for all insects. Nature communications, 11(1), 576. https://doi.org/10.1038/s41467-020-14496-6
I was six in 1999, when I moved from Wuhan, Hubei, China to Cedar Falls, Iowa, USA — from the center of the Middle Kingdom to the heartland of America. Having grown up eating cheeseburgers and chicken nuggets with my Happy Meals in China, I distinctly remember my shock to find there were McDonald’s in the United States of America too. I am a child of globalization, a force that has connected everyone in the world in intricately interdependent ways. The same force has caused COVID-19 to spread so widely and quickly.
Wuhan was quarantined on January 23, 2020. My plans of visiting over the summer with my girlfriend to see my extended family in China went out the window. I video chatted with my grandmother in early February and the reality of the situation set in. She had been shut in her apartment for weeks, not even venturing out for groceries. She cried as she told me her best friend of over 60 years had passed away of COVID-19 after developing symptoms only 10 days prior. There was an outbreak in the small housing community where my mother grew up, and my grandmother personally knew nine people who died of COVID-19. She herself was prepared to die, too. Thankfully, she survived the outbreak and the strict quarantine, which has since been lifted. As COVID-19 spread around the world, I have since gone from worrying about my grandmother in Wuhan to my American host family grandmother in Cedar Falls, as well as my girlfriend’s grandparents who live in a nursing home in Ontario, Canada. Montreal, where I am writing, is currently under Level 4-Maximum Alert level lockdown. Viruses know no borders.
Luckily, science knows no borders either. Scientists and researchers from all over the world are racing against the clock to better understand all aspects of the SARS-CoV-2 virus and the COVID-19 disease it causes, including the origins of the virus, its genetic and molecular basis, improved detection of infection, enhanced primary care for patients. They are also developing therapies and vaccines.
The World Health Organization has developed an open database of global scientific literature on COVID-19 that contains over 100,000 articles spanning at least 26 different languages with the hopes of accelerating research and development to contain the pandemic and improve care. Many of these studies are conducted by international teams of scientists whose sustained collaboration is crucial to advancing research on COVID-19. For example, the initial description of the SARS-CoV-2 virus was authored by scientists from the Netherlands, Russia, United States, Germany, China and Spain.
Another fruitful and longstanding international collaboration exists between EcoHealth Alliance, a New York City nonprofit, and the Wuhan Institute of Virology (WIV) of the Chinese Academy of Sciences. For around 15 years, this group of researchers studied coronaviruses in bats and significantly improved our understanding of how such viruses could jump into humans by sampling wild bats, other wildlife and humans in southern China. Among many papers produced by this collaboration, these studies also produced baseline genetic sequences of bat coronaviruses, some of which were critical in the testing of the antiviral drug remdesivir.
Unfortunately, in April, the National Institutes of Health (NIH) canceled an already-funded multimillion-dollar grant for this collaboration seven days after President Donald Trump said in a press conference that “We will end that grant very quickly.” The outcry came quickly. Nearly 80 U.S. Nobel Prize winning scientists and 31 scientific societies called upon the NIH to act urgently to reconsider their decision.
Although Trump has said he has “high confidence” that the virus came from the Chinese lab at WIV, the overwhelming international scientific consensus is that SARS-CoV-2 originated naturally. The head of the lab at WIV has stated that the president’s “claim that SARS-CoV-2 was leaked from our institute totally contradicts the facts. It jeopardizes and affects our academic work and personal life. He owes us an apology.”
In a tit-for-tat fashion, the Chinese foreign ministry spokesperson Zhao Lijian has promoted the possibility, without any evidence, that the U.S. Army had planted the virus in Wuhan. As the COVID-19 pandemic rages in the U.S. amid a continuing trade war, U.S.-China relations are undergoing unprecedented stress. In a recent Pew Research poll, 73 percent of U.S. adults were found to have an unfavorable view of China. Anti-American sentiment is also commonly found across Chinese society with a poll in May showing that, on a scale of 1-10, the view of Americans had fallen a full point to 4.77 in less than a year.
Anna Shvets from Pexels
The deterioration of U.S.-China relations has widespread ramifications. As United Nations Secretary-General António Guterres said in September, “Our world cannot afford a future where the two largest economies split the globe in a great fracture — each with its own trade and financial rules and internet and artificial intelligence capacities.” Regarding the pandemic, he said, “populism and nationalism have failed” and “those approaches to contain the virus have often made things manifestly worse.”
For me personally, internationalism has been a defining characteristic of my life and has played a core role in my scientific career. After finishing my undergrad in environmental sciences at Notre Dame, I pursued my masters in evolutionary biology in Netherlands, France and Sweden, and I am now doing my Ph.D. in Canada at the Redpath Museum of McGill University.
In 2018, I started a project to develop a genetic method to detect the DNA of animals from steeped alcohol, which will become a chapter of my Ph.D. thesis. Steeped alcohol is a popular form of traditional Chinese medicine that involves soaking plants and the bodies of animals in high-proof baijiu liquor. The most prized forms of steeped alcohol used endangered species like tigers, pangolins and snakes. Along with my Chinese collaborators, we hope that this forensic technology could potentially be used to monitor and combat illegal wildlife trafficking by providing law enforcement a way of checking for traces of illicit animal products.
Because of my personal connections to the COVID-19 pandemic, I have become more interested in human health aspects of wildlife conservation. Through a conference, I connected with scientists at the Bronx Zoo and the Wildlife Conservation Society (WCS). After a few emails and a video meeting, I am happy to report that I am now officially collaborating with the WCS and their Chinese counterparts on my steeped alcohol project. They have recently launched a similar initiative to develop a genetic method to identify endangered big cat species from confiscated animal products, including tiger bone wine. We will pool samples, international networks, computational resources, and molecular and bioinformatic expertise.
My interests for my postdoctoral research are shifting focus to address the crucial links between wildlife conservation and infectious diseases like COVID-19. Likely in continued collaboration with the WCS, I hope to use cutting-edge metagenomic methods to identify which animal species are more likely to harbor viruses that could spill over into human populations. Such genomic data could be used to predict which viral strains and traits are potentially more hazardous to human health, and to prioritize which wildlife species to focus on for targeted conservation efforts. This sort of research, which parallels the goals of EcoHealth Alliance and the Wuhan Institute of Virology, will help to prevent future outbreaks and another potential global catastrophe.
The war against viral pandemics will not be solved by any one individual, organization, or country. It is a global issue that will require extensive international collaboration and political unity. A fresh focus on wildlife conservation, increased investment to prevent wildlife trafficking, and further research into viral metagenomics are areas where all countries — especially the United States and China — can work toward shared goals.
A successful future will be built on solidarity, not division.
武汉加油！世界加油！Stay strong Wuhan! Stay strong world!
Charles Cong Xu is a Ph.D. candidate in the Department of Biology at the Redpath Museum at McGill University in Montreal. Visit his website charlescongxu.weebly.com or follow him on Twitter @CharlesCongXu.
Check out our coral research off Coibita Island, Panama. The research was completed during a course with the Smithsonian Tropical Research Institute and was inspired by Sir David Attenborough. The footage was captured by Dr. David Kline and the video was created by MK Hickox and Julia Briand. The research project represents the collaborative efforts of Julia Briand, Sarah Chamberland, Alexis Heckley, MK Hickox, and Charlotte Steeves.
“You count butterflies? They pay you? How do you get that job?”
This was a common refrain whenever I explained what I did for a living.
And they are right: standing on a rise on a sunny day, overlooking a tangle of greenery with jewelled wings flitting in every direction, I could not believe that someone was paying me to do this. Counting monarch butterflies for the Montreal Insectarium was surely the best job in the world.
The summer of 2019 was a great one for monarchs in Canada. But it was also bittersweet for the mottled duskywing (Erynnis martialis): This skipper butterfly–found in rocky outcrops–has disappeared across much of its range. On the glorious day when the photo (above) of my daughter was taken, we were helping Montreal Insectarium entomologist André-Philippe Drapeau Picard search for it.
So how did I get the best job in the world? Insectarium director Dr. Maxim Larrivée needed someone to analyze the butterfly sightings uploaded to the online butterfly websites eButterfly and Mission Monarch. I undertook this work as a master’s student for McGill University plant scientist Dr. Sylvie de Blois.
Monarch Hot and Cold Spots
(Fig. 1) Circled red dots = areas with the greatest number of butterflies per sample. Circled blue dots) near Toronto and Ottawa (Note: urban areas [Toronto & and Ottawa] also appear in red)
This analysis revealed that there seemed to be an unaccountable monarch hot spot on the north shore of Lake Ontario, between Toronto and Kingston (circled area with red dots, Fig. 1). This was puzzling: why are more monarchs found there? They pass fly over the cold spot southwest of Toronto (circled blue dots, Fig. 1), through the ‘desert’ that is urban Toronto, to an area stretching from Prince Edward county up to the Kawarthas. How are conditions better there?
Monarch Life Cycle & Decline
Fig 2. Monarch life cycle. Egg to adult (22 – 37 days if temperatures are 22 °C – 28 °C). Source: Journey North
The monarch butterfly is an iconic insect that lays its eggs on milkweed plants, the only suitable food source for its caterpillars.
Every fall, Canadian monarch butterflies born east of the Rockies travel to a mountain range in Mexico where they spend the winter, before mating and flying back north to Texas to lay eggs in the spring (Fig. 2). Subsequent generations live only a few weeks, spreading out to the Midwest and north to Canada. Two more generations are born and die before conditions bring them up between Lake Michigan and Erie along the north shore of Lake Ontario to the hot spot we noticed.
Fig 2. Monarch life cycle. Egg to adult (22 – 37 days if temperatures are 22 °C – 28 °C). Source: Journey North
Understanding the presence of monarchs in southern Ontario has become a matter of some urgency, as the monarch population east of the Rocky Mountains has decreased by over 80% since 1994 (Brower and al. 2012; Fig. 3). Most monarchs used to migrate from the Midwest, but changing agricultural practices are thought to have reduced those populations. American monarch watchers are noticing that more individuals seem to be coming from Canada in recent years.
But we know very little about the Canadian population. Is there enough milkweed for them? What is attracting them?
Butterfly Summer
So last summer I set out to answer those questions and to see what could be learned about the whereabouts of monarchs in Canada. I was accompanied by my daughter Maeve, who is able to put up with a lot so long as there is an access to wifi, a shower, and ice cream at the end of it. We visited 80 examples of the uploaded observation sites (Fig. 4) over two weeks at the end of June, and again at the beginning of August.
(Fig. 4) All sites all regions
To monitor the two generations normally born here in Canada, we chose 20 sites in each of the following four regions: the hot spot, the cold spot southwest of Toronto, a neutral region between Toronto and the hot spot, and in urban Toronto itself. I wanted to see what was different about the hotspot, and I was curious about the impact of urban pollinator gardens.
Prince Edward peninsula Uxbridge Countryside Preserve
It was a good summer to do this: spring was late, but conditions were ideal by August and monarchs were everywhere. There were some glorious locations in the hot spot: in the Prince Edward peninsula, there were nearly 40 square kilometers of old farmland returning to juniper scrub. We had reports of hundreds of monarchs sighted after walking for only a few kilometers. One of our favorite spots was Uxbridge Countryside Preserve: it contained a remnant of tall-grass prairie, and an intimidating number of milkweed. Just ask Maeve, who stopped turning leaves after 400 plants.
Bowmanville Valley Trail
East Point Park
We averaged about 6 sites a day, which made for some long days! A shout out to Google maps, as we could never have moved so speedily without the little blue dot. At every site, we measured environmental factors such as temperature and wind speed, as well as the type of land cover and surrounding land use. Once we listed the plants found within 12 m² plots – representing the center, middle, and edge of the area – we then counted the eggs, caterpillars, and adult butterflies. My daughter was assigned to young monarchs, turning over innumerable milkweed leaves before reaching a total of 2000 juveniles.
A Terrible, Horrible, No Good, Very Bad Day
It was the best job − most days, that is! My first unscientific conclusion is that monarch butterflies are found in conjunction with mosquitoes, thistles, poison ivy (we trekked through fields of thigh-high poison ivy) … and wasps!
Site Mp117513 will live in infamy: this location was quite remote, along an ATV path so worn down that poison ivy ran along the car doors for kilometers. Then I stepped on a wasp nest while checking the milkweed, and I was instantly covered by furious wasps. They must have got me at least 20 times on each elbow.
Site Mp117513
On top of this, a lacrosse tournament had occupied all the hotel rooms, and the car started to make an ugly sound. The only room we could find was in Oshawa’s local crack den, the sort of place where waxy men sit on lawn chairs outside their room, and receive a stream of dubious visitors. The sort of place where you get your daughter, your computer, and your data in, bolt the door and pray your car will still be there in the morning.
Fortunately, a car wash and new brake pads later, we found more salubrious accommodation at The Hive B&B (above middle), an old church where a colony of bees had taken up residence in the wall. This appealed to my black sense of humor, though I did not want to sleep in the room next to the hive! Apparently, this wall (above right) has leaked honey in the past.
Urban Butterflying
Monarch butterflies can usually be found in a tangle of milkweed, goldenrod and other asters in the sunshine. Such a combination could be found in the unlikeliest of places: someone saw a monarch in this planter on Bloor Street in downtown Toronto (left), opposite the Tiffany jewelry store. So after counting the begonias, we went in for our Breakfast at Tiffany’s moment, and were offered little cookies in Tiffany blue (middle).
We wound up in some odd places, including people’s backyards (above left) and a forested city park used as a meeting place for young men in inappropriate footwear (not pictured).
If there was a likely nectaring source, the monarchs were all over it. In Tommy Thompson Park, on an island that stretches from downtown Toronto into Lake Ontario, cars are forbidden, so urban biology required us to rent bikes for the day (above middle & right).
Guildhall Park, on the eastern limit of Toronto, is a former artists’ colony where old statuary from demolished buildings is scattered around the park. It has become a wedding emporium, where thistles and joe pye weed covered in monarchs are mixed in with brides from all the world’s cultures (above).
Left: One of our award-winning milkweeds this summer, with 5 large instars (caterpillar stages) all chewing busily. Not much left!
By the August migration, monarchs could reliably be found on bull thistle, which was not a plant I thought of as an important nectaring source. I am unsure whether they favour this plant because it has a lot of nectar, or because it is the only available nectar source. Having spent a lifetime digging up the thistles in my garden, I am now contemplating keeping some.
I must credit the Province of Ontario and the City of Toronto with preserving much of their natural capital: unused areas of public parks have been returned to nectaring plants, and everywhere I went there were conservation areas − often simply a parking lot and a path.
Encounters
One of the greatest joys was meeting some of the people who had uploaded sightings:
Karen Root has created a gorgeous farm devoted to pollinators.
Betty McCulloch has been tagging monarchs for 5 years. Two of the monarchs she tagged from the summer were recovered in Mexico.
Bryson is a budding young entomologist, who created a scrapbook of his insect encounters.
Insects I Have Known
And then there were the bugs! My background is in plant science, so it was a wonder and delight to encounter so many new insect species. We were especially fond of the swallowtails, which like the monarch, seemed to do well that summer. We encountered numbers of giant swallowtails (Papilio cresphontes) around Hamilton (above). This butterfly is so large it must hover while it nectars (making still photography challenging!)
As I couldn’t justify collecting live butterflies without a scientific purpose, we instead became expert spotters of flapping wings by the side of the road, and put up a collection of wings taken from the bumpers of railway trucks encountered at hotels.
My Smashed Butterfly collection amuses the entomologists.
Conclusions
After all that, what did we learn? It is still too early to draw any scientific conclusions, as the price for my delightful summer is a winter spent hunched over a computer analyzing data. Anecdotally, however, I am entertaining the theory that either the extent of the likely land cover available to the monarchs in the hotspot, or an attraction to the remnant tall-grass prairie, is inducing them to return to the area, or leading to greater reproductive success there than elsewhere.
Maintaining late-season nectaring resources seems to be vital, especially in Toronto. By August, every monarch was heading in a southwesterly direction. Once they reached Lake Ontario, they turned west along the shoreline. We could stop at a likely intersection and see dozens fly over in minutes. This route brought them straight through Toronto, where nectaring resources were scarce. There were many reports of the numbers of monarchs seen in Toronto this summer. If you planted milkweed, they would come!
I also saw a lot of dog-strangling vine, which is an invasive milkweed that outcompetes the native species, leading to food deprivation for monarch caterpillars. In some areas, it has completely taken over the land where hundreds of monarchs had previously been reported. Now there was none.
Dog-strangling vine
And what of the mottled duskywing? Sadly, we never saw it, but it made us feel the abundance of monarchs even more keenly; a great reminder to cherish and protect what we still have.
Thanks to Insectarium de Montréal, McGill University, Drs. Maxim Larrivée and Sylvie de Blois, André-Philippe Drapeau Picard, and Maeve Bohle.
Marian MacNair grew up on a farm in the B.C. interior, before becoming a journalist and educator in Montreal. When she isn’t chasing butterflies, she maintains a blog and website: https://marianmacblog.com/
Reference
Brower, L. P., O. R. Taylor, E. H. Williams, D. A. Slayback, R. R. Zubieta and M. I. Ramirez. 2012. Decline of monarch butterflies overwintering in Mexico: is the migratory phenomenon at risk? Insect Conservation and Diversity, 5 (2) : 95-100.
Inamine, H., S.P. Ellner, J.P. Springer and A.A. Agrawal. 2016. Linking the continental migratory cycle of the monarch butterfly to understand its population decline. Oikos, 125:1081–1091.
