The monarch butterfly is a delicate and ethereal seeming creature that nonetheless manages the longest and most grueling migration in the insect world. During the spring season, these famously beautiful orange and black Lepidoptera can be found throughout the lower 48 states and even as far north as southern Canada. Monarchs are vulnerable to cold weather and so flee to warmer climes as winter approaches. West of the Rocky Mountains, monarchs head to the coasts of central and southern California where they ride out the winter in relative comfort. The butterfly population east of the Rockies heads south and for decades, the final destination of this population remained a mystery. It wasn’t until 1975 that a group of researchers finally stumbled across the monarch overwintering grounds high in the Sierra Madre Mountains of Mexico. That area is now a World Heritage Site called the Santuario Mariposa Monarca (or the Monarch Butterfly Biosphere Reserve). Within this winter hideaway, monarchs congregate by the millions, completely coating the pine and oyamel fir trees that constitute much of the flora of the high-altitude forest. With the advent of spring, the butterflies return north, dispersing across the East coast and the midwestern United States. As recently as the early 1990s it was still possible to find trees rooted in American soil that was completely coated in a fluttering garment of black and orange. In this day and age, however, monarch sightings have grown increasingly few and far between.
It has become undeniably apparent that butterfly populations are plummeting. The drop has been so precipitous and so quick that the charismatic insect hasn’t yet been granted endangered species status. Both the International Union for Conservation of Nature (IUCN) and the US Fish & Wildlife Service are scrambling to review the data related to monarch population collapse. The catastrophic decline in butterfly numbers has been severe enough, however, to warrant immediate conservation action even as those agencies work through the data. In June 2014, President Obama issued a Presidential Memorandum that established a Pollinator Health Task Force. This was partly in response to the epidemic of colony collapse disorder decimating honey bee populations, but the memorandum also focused on butterflies as another important pollinator. The memorandum states that “[t]he number of migrating Monarch butterflies sank to the lowest recorded population level in 2013–14, and there is an imminent risk of failed migration.”
This concern over pollinator decline also leads to the filing of a petition with the US Department of the Interior to have the monarch declared an endangered species. If granted, the monarch would obtain further legal protections under the Endangered Species Act. Unsurprisingly, this petition was sponsored by the Center for Biological Diversity, based in Oakland, California. What is more interesting is that it was co-sponsored by the Center for Food Safety, an agency concerned with the sustainability of our farming practices. The plight of the monarch isn’t simply a matter of a pretty insect at risk; their decline has ramifications that impact our entire agricultural industry.
The increased attention being paid to endangered wildlife and ecosystems originating from commercial and industrial interests is a signal. It demonstrates that we as a species are beginning to understand two key points: one, that our habits and attitudes have major effects on the life forms we share the planet with and two, that the struggles of these life forms impact us in turn.
Monarch butterflies are suffering from a barrage of human-sourced issues. Monarchs lay their eggs on milkweed, a weed that is targeted by agricultural herbicides. The poisons we use to benefit our crops kill not only the nursery plant of the monarch but huge swaths of wildflowers that the butterflies depend on for food as well. The monarchs lay on milkweed because their larval young will feed on it, ingesting toxins as they go. These toxins, while harmless to the caterpillar, make it distasteful and poisonous to potential predators. Unfortunately, this clever adaptation, quite effective against native predators, has proven to be ineffective against at least two invasive species; the Asian lady beetle and the Chinese mantis. Other invasives, plants this time, further complicate the problem. Monarchs on the quest for a nesting site, often confuse black swallow-wort and pale swallow-wort for their preferred milkweed. The invasive European plants are poisonous to monarchs and the caterpillars unfortunate enough to be born on them invariably die.
As winter approaches and the monarchs begin their flight south, the situation worsens. All of their issues with finding food and avoiding predators are compounded by the exertion required to cross the many hundreds or thousands of miles between their northern range and their southern range. Monarchs are unwilling or unable to cross the Gulf of Mexico and so must make the long trip around before heading to the Sierra Madres. The result of these many factors has led to a 50% decline in the butterfly population west of the Rockies since 1997 (these are the butterflies headed to the California coasts) and a 90% decline in the population east of the Rockies since 1995 (this is the population that winds up in Mexico). Truly, the situation looks grim.
Typically, this is where the discussion ends. We conclude with the understanding that human beings are the apocalypse, that our agriculture, our industry, and our rampant consumption serve to push our neighboring wildlife inexorably toward the cliff of extinction. Quite often an article like this ends by bemoaning our cataclysmic ways and putting forth a call to action, a plea to open our eyes and take a hard look at what we’re doing and how to change. These are critically necessary conversations that must be had. Certain aspects of human industry and development are having dramatic effects on the world at large, but in this edition of Conservation Corner, we want to use the situation to illustrate another point entirely.
Throughout the long history of life on this planet, the evolution of species has been driven by the process of natural selection. On a constantly changing globe, every species is exposed to changing situations; glaciers form and melt, volcanos erupt, the climate grows a few degrees cooler, then warms back up again. The animals that can survive these changes breed and subtly shift the nature of their species one way or another. The generation descending from the last is slightly modified and the modifications that yield the best results typically persist. It’s a slow moving and granular process occurring over millions of years and so we don’t expect to see much evidence of it over the limited span of time in which we humans have been around to influence it.
Humanity now applies seemingly unprecedented pressures on the environment. Utilizing dams and pipelines, we have diverted the flow of rivers the world over. A process which would have taken centuries through the slow processes of sedimentation and erosion can now take place in a geological blink of the eye. Likewise, we are tapping oil reserves and releasing sequestered carbon at a pace many thousands of times faster than the rate by which it was initially pulled from the sky. These changes and others, taking place over a compressed period of time constitute daunting challenges to many species and have undoubtedly led to extinctions. The situation is growing increasingly dire, but what’s important to bear in mind is this; the flora and fauna of this planet have always had to surmount obstacles to survive. What we humans have brought to bear may be impressive, but it is not unprecedented. Humanity and the pressures we bring with us are merely the latest variation on the theme of dynamic change. A theme which has driven natural selection since the first single-celled organism appeared in the primordial sea.
This point is not made to absolve humanity of our responsibilities but rather to highlight the incredible resilience of life on this planet. As Dr. Ian Malcolm proclaimed in the oft under-rated Jurassic Park, “Life breaks free, it expands to new territories and crashes through barriers, painfully, maybe even dangerously, but… life finds a way.” To take it back to the monarchs, as the milkweed declines, they’re laying eggs on the swallow-worts. The swallow-worts are killing them so that experiment has failed but the point is that they’re adapting to changed circumstances rather than giving up en masse and falling down dead.
A more interesting and potentially more successful adaptive behavior has recently become apparent. While the human-caused decline in milkweed and the invasive predators we’ve unwittingly introduced have created potentially insurmountable problems for the monarchs, our dependence on oil has surprisingly, offered them an opportunity.
The southbound monarchs fly around the Gulf of Mexico rather than over it; a journey that exposes them to increased risks and requires far more energy. Since we have peppered the gulf with oil rigs, some monarchs have begun to use the industrial platforms as stopover points. With the sudden appearance of artificial rest stops, a journey across the gulf becomes difficult rather than impossible. We’ve unwittingly created problems, but we’ve also unwittingly created opportunities and the monarch butterfly is not alone in taking advantage.
The novel migratory path of monarchs is just one example of the innumerable species that have found ways to adapt to human wrought change. For decades, if not centuries, we have endeavored to bring about the extinction of a whole host of parasitic and infectious species. We may crow about the annihilation of smallpox, but what about the flu, or the common cold, or salmonella? Every time we use our vaunted human intellect and technological advantage to attack these species, they rally, surviving not just in distant isolated crevices of the world, but in our very bodies. Likewise, few stop to consider the ecological value of rats, mice, or roaches because the possibility of their extinction is laughable. We have taken every possible measure to destroy or drive off these incredibly resilient species, but have never come close to achieving that goal.
Perhaps the most surprising example of animal adaptation to human advancement to appear in the last few years is that of the coyote. Coyotes have long proven resilient in the face of human antagonism, not only surviving in rural areas where they are almost universally classified as pests, but readily colonizing our suburban neighborhoods as well. These creatures have proven so malleable in behavior, so adaptable to changing conditions that recently it’s been discovered that coyotes have colonized metropolitan Chicago. There in the heart of the third most populous city in the nation, as many as 2,000 coyotes are living fairly comfortable lives right under our noses. They have transitioned from a life in daylight to a largely nocturnal lifestyle. An animal adapted to life in the forests and plains is now learning to follow traffic patterns and avoid vehicles. They’ve become so adept at living without conflict among millions of human neighbors that one coyote pair managed to raise a litter of pups in the parking lot of Soldier Field Stadium.
We live in an era in which the evidence of human progress and habitation can be found on every continent, in every ecosystem, and even orbiting the planet. Some scientists are arguing to rename this geological epoch the Anthropocene to reflect the possibility that we’ve entered the age of man. Our influence on this globe is immense and we as a species must be aware of what we do and how we go about doing it. We should care about the organisms that are declining in the face of our advancement and for the large part, we do. We should take measures to mitigate our impact on the world at large, to learn to live in balance with our neighbors. As we take on these noble goals, however, it is important not to exaggerate our power. We are not the lords of this planet, we are merely a very large and influential population on it.
Early life enjoyed a methane rich atmosphere and died off in droves when photosynthetic cyanobacteria flooded the skies with toxic oxygen. Life adapted to the new order and now most organisms on this planet actually require oxygen to survive. When the Earth cooled and sheets of ice covered nearly the entire globe, many species died out, but life carried on, adapting, changing, and thriving in a frozen world. When a massive meteor struck the planet, it brought about the end of the dinosaurs, and as they died, other creatures hunkered down and survived. Now the mammalian descendants of that small shrew-like species dominate the globe. No matter what force for change rolls across this dynamic planet of ours, life finds a way to adapt to it. In the face of a changing world, life will continue to modify and thrive. Whether we humans are the agents of change or not is largely irrelevant, life will find a way.