Biologist Ryan Walsh releases monarch butterflies at the Toledo Zoo. The September release was the zoo’s second. Last year, none from Toledo was found in Mexico. This discovery meant that dozens survived the perilous trek.
Nine monarch butterflies released by the Toledo Zoo last fall have been found in the insect’s wintering region of central Mexico, pumping a shot of adrenaline into the zoo’s captive-bred monarch butterfly program.
Here’s why that’s important: Finding a butterfly in the wild is akin to finding a needle in a haystack, especially after they wind up in central Mexico’s oyamel fir forests in the states of Mexico and Michoacan.
That’s the temperature-sensitive insect’s final destination before it produces offspring that keep the cycle going with successive generations that summer up north and return to Mexico. Five or more generations a year are part of that cycle.
For many monarchs coming down from Canada and states east of the Rocky Mountains, that can be a journey of 3,000 miles or more.
Monarchs west of the Rockies and from the Gulf Coast also are believed to migrate great distances. Some are believed to stay permanently in Florida. But few migrate as far as those east of the Rocky Mountains do — the longest insect journey on Earth, said Ryan Walsh, the Toledo Zoo’s Wild Toledo coordinator.
Finding nine of them likely means that dozens of the 760 monarchs the zoo released last fall survived the arduous trip, Mr. Walsh said.
“It’s a big sign that the monarchs we are releasing are having a positive impact,” he said.
In the big picture the nine monarchs, found by Mexican residents and members of Kansas-based Monarch Watch, support the zoo’s belief that its captive-breeding program, now two years old, is working — at least in terms of producing a viable population to help bolster numbers.
None from Toledo were found in Mexico a year ago, months after the Toledo Zoo had its first release of captive-born monarchs.
That was in the fall of 2014, when it released 250 butterflies.
“Just because butterflies aren’t recovered doesn’t mean they didn’t make it down there,” Mr. Walsh said.
The Toledo Zoo is one of many zoos, universities, and groups trying to keep the monarch from vanishing by breeding them in greenhouses and releasing them into the wild, Mr. Walsh said.
Wild monarch butterfly populations have declined an estimated 90 percent over the past two decades, with habitat loss in the Midwest cited as a major cause. Monarchs feed exclusively on milkweed, which has been affected by anything from heavy pesticide use to roadside-mowing operations.
The late Doris Stifel of West Toledo had a role in helping researchers identify the Toledo-to-Mexico connection years ago.
The truth is, though, that scientists “don’t know the exact migration route because that would involve intercepting butterflies several times during their migration,” Mr. Walsh said.
Wind and storm patterns like play roles too.
“The monarchs are tracked in a lot of ways by luck and sheer numbers,” Mr. Walsh said. “Each tag has an email address and phone number where spotters can report the tag number to Monarch Watch.”
Before their release from Toledo, the monarchs have a sticky tag attached to them with contact information. The white, round tags are the size of human fingertips. A zoo video shows they are small enough to be held up by the end of a paper clip.
The monarchs are raised at the zoo’s on-site greenhouse.
Even though Mr. Walsh and many other researchers are optimistic about captive-bred release programs, some fear it could have the unintended consequence of spreading disease and accelerating the butterfly’s decline.
A three-page statement released last Oct. 8 by 10 monarch researchers — ranging from Georgia to Minnesota to Washington State — said mass releases “could do more harm than good.”
The Toledo Zoo is aware of such concerns and, as a result, goes to great lengths to keep the greenhouse as sterile as possible, Mr. Walsh said.
All incoming eggs are bleached and only milkweed grown in the zoo’s greenhouse is used, he said.
“We also test a subset of all released animals to ensure our stock is disease-free prior to release,” Mr. Walsh said.
The Toledo Zoo plans to release another 700 to 800 captive-bred monarchs between late August and late September, Mr. Walsh said.
Money for the program comes from contributions and adoptions raised by its Zoo PAL program, he said.