Migratory species across North America are on the move as fall progresses toward winter. Right now is ideal timing to observe bird migration with many uncommonly observed species moving through our area on their way to the tropics. I’ve always marveled at the sheer distance some of these species travel.
It’s hard to understand how the risks involved in such great distances add up to be worth it for the perpetuation of their numbers. I find it fascinating to think about how this behavior developed across the evolutionary timescale as I observe this annual migration each year.
One migratory species that has captivated the public in recent times is the monarch butterfly (Danaus plexippus). Some of this captivation is tied to the monarch’s declining populations across North America, which is currently at risk, but it’s also the incredible migration distance (up to 2,500 miles) which draws attention.
However, there is some confusion on how the monarch life cycle and migration function, which has led to quite a few questions from the public over recent weeks as monarchs have begun their annual move south.
Its been hard to find monarchs in central Illinois this week, although I was seeing them as recently as early last week. What most folks don’t realize is that the monarchs we are seeing leave central Illinois in the fall are not the same individuals that arrived in the spring. Over the course of summer, monarchs have up to three generations of adults in our area. It’s the final generation of the year that migrates south to overwinter.
Throughout the summer, monarchs typically have a four-to-six-week lifespan. However, the final generation for the year has a much a longer life, spanning many months in their overwintering location. This generation also begins the spring migration north but never makes it as far as Illinois. They will lay eggs along the way that hatch into the first generation of the year that reaches us.
Monarchs in our area and all others east of the Rocky Mountains migrate to Mexico to overwinter. The one exception is some populations of non-migratory monarchs in Florida, which experience a warm enough climate year-round that there is no need to move further south. West of the Rockies, monarch populations overwinter in coastal California, or some make the trip south to Mexico.
As cooler nights have set in over recent weeks, I’ve received questions from concerned monarch spotters wondering if the individuals they are observing in their yards and gardens will make it south before succumbing to the cold. Many folks simply want to know what they can do to help, and there really isn’t a whole lot you can do at this point in the season. It’s best to let nature take its course for these individuals.
If you are interested in supporting migrating monarchs, the best thing you can do is add fall-blooming plants to your garden. The annual migration requires large amounts of energy for each butterfly making the long journey, and the nectar in your garden can help fuel the trek.
Right now, I have multiple species of native asters and a few goldenrods still in full bloom. Aromatic aster (Symphyotrichum oblongifolium) has not even started blooming but will begin in coming weeks and typically blooms until killing frosts arrive much later in the season. Although it may be too late for migrating monarchs, it can be a valuable food source for other pollinators that are still active.
Even non-native species can be of benefit since they offer nectar. Numerous sedums (Sedum spp.) are blooming now and have been for weeks. These beautiful succulents provide ample blooms in fall, attracting various butterfly species.
Mexican sunflower (Tithonia rotundifolia) is a non-native annual that is highly attractive to monarchs and blooms late into the season. This member of the daisy plants develops into a large bushy plant with tons of blooms from mid-summer until frost. With tons of blooms come tons of seeds, so beware that this annual can readily self-seed.
Take a look around your garden right now to see what’s in bloom, and consider what you might be able to add next year. Fall bloomers certainly benefit the butterflies but also help your garden space end the season with a colorful bang!
Join the East Central Illinois Master Naturalists and Dr. Eric R. Larson for ‘Environmental DNA to Monitor Plant and Animal Communities’ at 7 p.m. Monday. More information is available at go.illinois.edu/EnvDNA.