Drought creates a challenge for monarch migration
Peak of migration due in Oklahoma last week of September
The big orange-and-black season is upon Oklahoma. Monarch butterfly season, that is, and the iconic pollinators have a demanding road schedule ahead.
The largest generation of the butterflies is emerging from chrysalises locally, while others are migrating through, from northern states to over-wintering grounds in Mexico. Faded and battered veterans of the last generation continue to find nectar in local blooms while their bigger, brighter offspring hit the skies to head south.
“You’ll be seeing them pretty quick,” said Chip Taylor, director of Monarch Watch, based at the University of Kansas at Lawrence. “They’ve been coming through here the last five or six days… Generally (Oklahoma) should see pretty good numbers into the 26th and 27th of September at your latitudes.”
In a good year, monarch numbers peak by fall migration after the fourth (sometimes fifth) generation of production during the March-August breeding season. At no other time of year is the population as large as it is now in number and size. While the wingspan of earlier monarch generations is generally 3.5 to 4 inches, most migrating adult monarchs have wingspans over 4 inches. The overwintering generation will travel 3,000 miles and will live eight times longer than their parents, grandparents, and great-grandparents, so they can return next spring and give rise to the following year’s generations.
Tulsa Urban Wilderness Coalition marks the season 9 a.m.-1 p.m. Saturday with its eighth annual Monarchs On The Mountain Festival. It has a new location in west Tulsa at Chandler Park, 6500 W. 21st St, after outgrowing its namesake birthplace, Turkey Mountain Recreation Area. Educational presentations, plant sales, activities for children, a chance to see butterflies and caterpillars–and to hit the food trucks–draw a crowd.
“Moving is something we’ve talked about for several years,” said Marci Hawkins, Monarch Watch Conservation Specialist for Oklahoma. “Last year, we had as many booths as we could fit and all the parking and shuttles we could manage. We had overwhelmed the area. Chandler Park is a beautiful facility for the festival and a beautiful high place; we wanted to keep it on a mountain. People who don’t know about Chandler Park will discover a place they want to return to.”
The monarchs are “right on time” this year, Taylor said. But if the push seems early to you, you’re not wrong.
Celestial cues put the butterflies into migration mode. The angle of the sun at solar noon at any given latitude sets the stage, Taylor said. But weather is a factor in the timing and how concentrated pushes might be. For example, cold fronts and northerly breezes can create a noticeable “push” for a day or two. Other times, the insects trickle through day by day.
“In recent years, it has been later because we’ve had warmer than normal periods in September,” Taylor said. “It’s not good when the temperatures are in the 80s and 90s. It slows them down. When temperatures are in the low 80s, the 70s, even the 60s, they run pretty much on time in terms of the long-term record.”
Most monarchs will be out of the state by the first weeks of October, and some will be arriving in Mexico then.
“It’s a drawn-out affair that doesn’t happen all at once,” Taylor said. “It’s a process of more than a month.”
The general health of the eastern monarch population, which is under consideration for listing as an endangered species by the U.S. Fish and Wildlife Service–is measured by the size, in hectares, of roosts on wintering grounds in the mountainous oyamel fir forests in the Mexican states of Michoacan and Mexico. Western monarchs of California and different parts of Mexico also are a threatened group.
The population faces threats from pesticides, habitat loss, climate change, and other factors, but the act of migration has always come with risk.
Because of the widespread 2023 drought, flowers with life-sustaining nectar will not be as prevalent along the migration route, Taylor said. Water to help metabolize that food source also might be scarce.
“One thing you can do, if people see or know where there are roosts, in Oklahoma or Texas, if you’re in housing nearby, within 50 or 100 meters, you can water your lawn, and that will bring down the butterflies. We’ve had a lot of reports of people watering their lawns to take care of the butterflies, and it has become a fairly common thing in Texas. Don’t waste water, though. Just do it if the butterflies are there.”
