Last month, the International Union for Conservation of Nature placed the migratory monarch butterfly on its red list of endangered species. It’s been a long time coming. Monarchs are the poster child for the insect world. Tall and charismatic, everyone loves them and is much more likely to want to help them than, say, our endangered burial beetle or ringed bughaunter.
Monarch butterflies have been in decline for some time, so why list them now? In many places, their population is rapidly collapsing. The western population, for example, is the most endangered, “having declined by about 99.9% from 10 million to 1,914 butterflies between the 1980s and 2021. The largest population in the ‘is also declined by 84% from 1996 to 2014. There are always concerns about whether enough butterflies are surviving to sustain populations and prevent extinction,” according to a recent IUCN press release. what it means to be endangered is the intensive care unit of conservation efforts.These animals are on the brink of extinction.
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What causes this decline? Various human practices in their wintering grounds and along their migratory routes. There is the loss of their winter shelter areas in Mexico and California due to logging, legal and illegal, to open up land for agriculture and urban development. The use of pesticides and herbicides for industrial agriculture along their migratory routes kills a wide range of insects and birds, as well as the milkweed plants that are an integral part of the monarch’s life cycle.
Climate change is the latest and greatest threat. Much of the reason western populations are declining at such a catastrophic rate is due to the increased frequency of wildfires, drought, and extreme temperatures in the west. Additionally, across Central and North America, “warmer temperatures and earlier springs along monarch migratory routes could create a lag in time or space between monarch breeding cycles while throughout their northward migration (April to August) and the growth and survival of milkweed plants consumed by monarch caterpillars,” according to seagrant.umaine.edu.
The environmental threats monarchs face seem daunting. In 2014, I became aware of the importance of milkweed and its absence in my garden. This was before the impact of climate change was fully realized. I wrote: “One could argue that monarch butterflies are a tenuous species, relying on a fragile web of improbable coincidences; perfect conditions at every stage of their migration, perfect weather in the south, perfect timing so that the one plant they need to succeed, milkweed, can flourish. Perhaps they are destined for early extinction, even without human encroachment on their migratory routes. Or, perhaps, they are perfectly adapted to their world.
“I personally don’t want to be part of their demise. I’m going to grow these two milkweed plants near the chicken coop and I’m going to try to convince my neighbor not to mow the part of his field where the milkweed grows and I hope some monarchs will travel north this summer and find a safe haven in my garden.
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I’m still optimistic that we can make a difference for monarchs (and other wildlife). Since then, we have grown a larger plot of native common milkweed (Asclepias syriaca) and added two more native species of northeastern swamp milkweed (Asclepias incarnata) and orange milkweed (Asclepias tuberosa). We also plant as many native wildflowers as possible. Adult monarch butterflies feed on a variety of wildflowers, not just milkweed. The native part is the key. The non-native tropical milkweed (Asclepias curassavica) is deadly to monarch butterflies in a variety of ways. It carries disease, disrupts migratory behavior and, in a warming climate, becomes more toxic to caterpillars! Monarch caterpillars feed exclusively on milkweed whose sap is somewhat toxic. This toxin is retained by the caterpillars and is what makes the caterpillars and adults unpalatable to predators (hence the striking warning coloration of both). As it warms, non-native tropical milkweed increases the production of these toxins, unlike our native milkweeds. This is just one example of the many reasons why planting native species is generally a safer bet than non-native species.
The Monarch Butterfly Red List is just one more call to action for all humans to work towards a more sustainable future. Everything we do right now to help monarch butterflies recover, from planting native wildflowers to choosing organically grown products, to reducing our carbon footprint, will not only benefit the butterflies monarchs, but to all life on planet Earth.
Susan Pike, researcher and teacher of environmental science and biology at Dover High School, welcomes your ideas for future topic topics. She is looking for readers to send her the signs of spring they notice so she can document them on her site pikes-hikes.com. Send your photos and observations to firstname.lastname@example.org. Read more of her Nature News columns online at Seacoastonline.com and pikes-hikes.com, and follow her on Instagram @pikeshikes.