By Chelsea Jandreau
The end of August is one of those liminal spaces where we seem to exist in two different seasons. According to the calendar, it will be summer for a few more weeks, and the daytime is still often warm and sunny enough to continue beach days and summer activities. However, the nights are starting to get colder and the stores are full of Halloween items and fall flavors. For many people, this is also a transitional time as they get ready for a new school year, changing schedules and shorter days.
Nature is also preparing to shift focus as well. With decreasing sunlight and temperatures, animals and plants will begin changing their activities or appearance. As I sit here and watch a hummingbird at the feeder, I think about the animals that make one of the biggest changes: migration. Many people think of birds when they think about fall migrations but there are some even smaller organisms that make this journey every year as well.
Monarch Butterflies are one well-known animal that makes an incredible journey. Not every Monarch born will migrate, but those that do will fly thousands of miles south to winter breeding grounds. This yearly cycle is determined by food availability, weather, and temperature.
Monarchs go through complete metamorphosis, which means they have a life cycle made up of four stages: egg, larva, pupa, and adult. A female Monarch has the capability to lay anywhere between 100 and 300 eggs during their relatively short lifespan. One by one, they lay a single, pale yellow egg on the underside of a milkweed leaf.
In less than a week, a tiny caterpillar will emerge. Beginning at just 2 – 6 mm long, it will devote its time as a larva to simply eating more milkweed. As it grows in size, it will molt, or shed, its outer layer of skin five times allowing it to grow into a 25 – 40 mm long, striped caterpillar. Each one of these stages is called an instar, and in total Monarchs will go through their larval stage in just two weeks. The caterpillar then sheds its skin one final time to enter its pupal stage. In another two weeks it will emerge into a large black and orange butterfly, and in a few days they will be able to lay eggs and continue the cycle.
However, any of those late summer Monarchs you see have another important task instead of laying eggs. These butterflies will enter a reproductive diapause to help them save energy for the coming migration south. This migration generation can live up to eight or nine months instead of just a few weeks like their earlier summer counterparts.
Many people have reported seeing fewer Monarchs this summer, and while these are often colloquial statements and not a direct result of an intentional count, they may be pointing to a decades long and increasingly troubled situation for the Monarch butterfly population as a whole.
Each winter, the World Wildlife Fund (WWF) does a survey measuring the area occupied by Monarch Butterflies. This year, the Monarch population was using only 0.9 hectares of available forest. This is a decrease from the last few years. The last time it was this low was a decade ago, and over the last several years the Monarch population has remained largely between 2 – 3 hectares, with one hopeful jump in 2019 when the butterflies were occupying 6 hectares. While it is absolutely normal for animal and plant populations to increase and decrease year to year, overall the Monarch population has been on a steady downward trend over the last 30 or so years.
Habitat plays a major role in this. Monarch Butterflies are specialists. As caterpillars, they only eat varieties of milkweed, and as adults, they have to find food and resting spots as they travel hundreds of miles to one of only three or four overwintering locations. The most populous overwintering site is, by far, the Oyamel Fir forests found on the mountain hillsides in central Mexico. There is also a population of Western Monarch Butterflies that spend winter in coastal California among the Monterey Pines, cypress, and eucalyptus trees.
A decrease in the types of habitats that support Monarch Butterflies is thought to be one of the most significant reasons their population is decreasing. Although there are several different kinds of milkweed, development has decreased its numbers and prevalence.
A butterfly’s source of energy is the nectar found in flowers. Monarchs are a little less picky on this front and will consume nectar from all kinds of flowers, but they are still wired to look for those native flowers first. A decrease in natural prairies and fields mean that native wildflowers are sometimes also fewer and far in between.
Weather patterns also have major effects on Monarch populations. Large storms, persistent droughts, and other long term climates patterns can affect the Monarch’s physical safety and the availability of food.
While things may be looking bleak, there are also people who are collecting data, planting habitats, and advocating for these butterflies. There have been community science projects involving thousands and volunteers and scientific studies going on since the mid-1900’s. Monarch Watch and Journey North are just two community science projects that you could get involved in to help track Monarchs and contribute data to research projects that help us learn more about these butterflies.
If you have the space and ability, or know someone who does, there are direct ways to contribute to these little butterflies. Planting and preserving milkweed plants allows butterflies to lay more eggs and caterpillars to have a better chance of finding enough food.
Intentionally growing native flowers and advocating to keep patches of unmown prairie or meadows around allow not only Monarchs, but plenty of other butterflies, the food they require to reproduce or migrate. Here in western New York, some native wildflowers Monarchs use are goldenrod, Joe Pye Weed, cone flowers and asters. This is a non-exhaustive list and some research or a visit to your local nursery or greenhouse can help you to figure out some more. Keeping pesticides away from native plants and your lawn can also help provide safe habitat for Monarch Butterflies.
Monarchs are not the only migrating insects. Other butterflies, including the Painted Lady and Red Admirals, and some varieties of dragonflies also migrate. So even though a large public focus has been on Monarch Butterflies, helping to grow and preserve habitat for these charismatic butterflies will also help some of our other insects.
Audubon Community Nature Center builds and nurtures connections between people and nature. ACNC is located just east of Route 62 between Warren and Jamestown. The trails are open from dawn to dusk and birds of prey can be viewed anytime the trails are open. The Nature Center is open from 10 a.m. until 4:30 p.m. daily except Sunday when it opens at 1 p.m. More information can be found online at auduboncnc.org or by calling (716) 569-2345.
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