Global climate change includes extreme weather conditions, and those conditions are turning into a significant threat to the environment. High winds can knock door trees, heavy rain can lead to flooding, and drought can wipe out entire ecosystems. These changes can threaten entire species, like the monarch butterfly, by destroying their habitats and disrupting their life cycles. Extreme weather can interfere with their usual behaviors in several different ways, and all of them are threatening their species.
A Disrupted Breeding Cycle
Monarch butterflies are migratory creatures. They travel more than 2,500 miles every year to spend winter months breeding in Mexico. Like most migratory creatures, they realize that it’s time to start moving based on local weather conditions. Extreme weather patterns can cause this migration to begin at the wrong time, which disrupts the entire cycle of traveling and reproducing. Butterflies that start migrating too early or too late will find themselves without access to their regular food supplies, which can ultimately prevent them from breeding the next generation and cause the species to decline.
Migration is dangerous. Some butterflies die during their journey to Mexico, but there are usually enough young individuals to make up for the loss. That changes when they have to travel through a major storm since butterflies have trouble surviving under these extreme conditions. The losses during migration due to severe weather can be significant, and they get compounded in later generations because fewer butterflies survive to breed.
A smaller breeding population means a decrease in the number of births, which makes the population even worse off for the next migration cycle. Even the butterflies that make it to Mexico run the risk of dying due to the storms that can rip through their breeding sites. According to Alejandro del Mazo, Mexico’s attorney general for environmental protection, a single year’s storms led to the deaths of approximately 7.4% of the Mexico’s migratory population. Monarch butterflies are not yet extremely endangered, but they will soon be at risk of extinction if they keep suffering losses on this scale.
Loss of Food
Monarch butterflies have a somewhat restricted diet. Adult moths can eat nectar from a variety of flowers, but larva can only eat milkweed. Extreme weather patterns can cause problems for hungry butterflies during both life stages. Periods of drought and high temperatures can reduce nectar production in flowers, which can cause monarch butterflies to starve. This problem is especially acute in regions where they need to compete with numerous other species for access to food.
Monarch butterfly larva is in even greater danger of losing food supply. Milkweed is sensitive to changes in temperature, and the populations don’t have any alternative food supplies that can alleviate the problem. Many farmers choose to exterminate milkweed to prevent it from interfering with their agriculture, which makes the problem even worse.
The monarch butterfly population might have been able to adapt to one of those problems, but the mix is becoming more and more dangerous. According to Eduardo Rendón of the World Wildlife Fund’s Monarch Butterfly Program, milkweed availability dropped 58% between 1999 and 2010. No species can experience such a drastic decrease in its food supply without suffering significant losses due to starvation.
Even butterfly larva that can find enough food is at risk for extreme weather conditions. The larva doesn’t migrate until they mature, but they are still at risk from any storms that occur near their breeding grounds. When storms knock down trees, larva gets crushed under them.
Sudden temperature decreases cause them to freeze to death before they can find shelter. Unusually high temperatures that last for an extended period can also be lethal because they are relatively vulnerable to changes in the environment. Eduardo Rendón attributes much of the recent population decrease to the impact of weather conditions and larva extinction.
Despite the risk of death due to extreme weather or starvation due to the loss of milkweed, the greatest threat to the monarch butterfly is habitat loss. Illegal logging contributes to the problem, but the weather is doing much more damage to their habitat than humans.
According to the World Wildlife Fund, extreme weather causes the loss of about 133 acres of forest near Mexico City during 2016, which was about four times the amount that illegal loggers destroyed. The butterflies can only reproduce in relatively old and well-developed forests, so the habitat loss can only be replaced over the course of many years. With all of the other factors that are putting the monarch butterfly at risk, there might not be enough time for the forests to recover before it’s too late.
Saving the Monarch Butterfly
It is clear that extreme weather is threatening the monarch butterfly population by killing individuals and destroying their habitats, but the species still has room to recover. Monarch butterflies have proven that they can adapt to a variety of circumstances as long as the changes are not too sudden or severe.
Taking action to reduce the impact of climate change has the potential to lessen the frequency of extreme weather conditions, which could do a lot to save these butterflies. If governments and individuals take action to prevent humans from making the problem worse by clearing land that the monarch butterflies need to survive, the population can start to recover.
The monarch butterfly is not in a safe position at the moment, but it can still have a bright future as long as people are willing to put in the effort to save it while the population is still capable of growing.