Tuesday, October 28, 2014

Monarchs again

I've previously written (see here and here) about the loss of monarch butterfly habitat and the resultant effect on the insect's population, before, but as the monarchs make their way back to Mexico for winter hibernation, it's worth nothing that concerns about the species' well-being remain:
For years, the worry about monarch butterflies has focused on the loss of habitat in their winter home in Mexico.

But as the butterflies make their way south through Texas this month, there's even more concern about where they spend their summers.

The loss of habitat in the Upper Midwest's Corn Belt has many worried about the monarch's ability to keep making the 2,000-mile trek to Mexico each year. Every year, the monarchs overwinter in Mexico, then fly to the southern United States, where they mate and produce a new generation of butterflies before dying off.

Even with favorable weather conditions this year, the monarch population, which ebbs and flows, isn't looking good, said Chip Taylor, director of Monarch Watch and professor of ecology and evolutionary biology at the University of Kansas.

"It's an uptick, but it's not a massive uptick," Taylor told the Fort Worth Star-Telegram. "What I've been predicting is a doubling of the population, but that's still a small population and one of the smallest on record."

Last year, an all-time low of 0.67 hectares, or about 33 million monarchs, were documented in the mountains west of Mexico City. The average population of monarchs in the last 20 years is about 6.39 hectares.

In the northern U.S. and southern Canada, the habitat loss is taking its toll.

"What we really have to deal with is the habitat issue," Taylor said. "We're losing over a million acres a year. If that trend doesn't stop, the population will continue to decline."

Overall, Taylor estimates, about 165 million acres of summer breeding grounds — nearly the size of Texas — have been lost.

"Given that loss of habitat, it's not at all surprising that the population has gone down," Taylor said. "If we want the numbers to come back up, we have to address the habitat loss issue."
Individuals can do their part by planting milkweed - the only plant that monarch larvae eat - in their gardens, but saving the monarch is also going to require assistance from agricultural interests (whose use of pesticides and herbicides is taking a toll on both the insect as well as its host plant) as well as state departments of transportation, who maintain landscaping along highways including the I-35 corridor that monarchs generally follow:
All of the monarch population east of the Rockies funnels through Texas on its way to Mexico.

Taylor said there needs to be a corridor along I-35 to keep the monarchs migrating from the Upper Midwest and southern Canada.

"Monarchs are basically on that I-35 corridor in both the spring and fall," Taylor said. "How do we treat roadsides to make them a more friendly place?"
Milkweed is a key feature of my little gardens, and over the past month or so the plants have been doing their intended job as monarch breeding grounds. Whenever possible, I collect the fifth instar caterpillars and put them in a tupperware container so that they can safely pupate away from the elements, predators, lawnmowers, etc. Once they emerge and their wings have dried, I release them. So far I've released four monarchs, including this beautiful lady:

I'm uncertain if any of these butterflies will make their way down to Mexico or if they will overwinter here, and in any case they're not going to make much of a difference in the species' overall population numbers. Still, I find raising these creatures to be enjoyable, and I like to think I'm doing my part, however small, to keep the monarch viable.

I'll plant more milkweed early next spring, in time for the migration back north. I urge anybody reading this to do the same.

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