In 2001, Barb Agnew, founder of Friends of the Monarch Trail, watched swarms of monarch butterflies roost in the trees along the trail on the County Grounds.
This year, she predicts, there may not even be a noticeable migration.
While monarch numbers are at record lows worldwide, Agnew and the other Friends are undaunted in their determination to bring the monarchs back to Tosa — even knowing the city has less land available for the butterflies than ever before. They held a discovery fair at the trail Sunday, complete with live music, a food truck, butterfly tagging and walks along the 11-acre preserve.
With roughly 200 people in attendance, Agnew said, the event was more successful than she had hoped.
According to data collected by the National Commission of Natural Protected Areas, the monarch population is at a record low. The group measures the population as the butterflies reach Mexico, their final migratory destination, by how many hectares — one hectare is equal to 1,000 square meters — the butterflies occupy.
Last year, monarchs occupied 1.19 hectares in Mexico. Their numbers in 2011 took up twice that, and in 2006 there were six times as many monarchs.
Chip Taylor, professor of ecology at the University of Kansas and founder of MonarchWatch.org, said there could be less than one hectare occupied by monarchs this year. The largest population of monarchs measured since 1994 occupied more than 20 hectares.
Taylor, who has studied monarchs since 1992, attributes the population decline to myriad factors, including a loss of nearly 30 million acres of habitat to corn and soybean agriculture and unusual weather patterns.
In Wauwatosa, monarchs lost more than 200 acres of habitat, Agnew said. When the Milwaukee Metropolitan Sewerage District created basins in the area, the trail lost nearly 100 acres. With further changes on the County Grounds, the monarch preserve now sits at only 11 acres.
With the Mandel Group's plans to develop much of the area around the preserve, acreage won't be lost, but the area may no longer be continuous habitat for butterflies.
Agnew stressed the importance of keeping land around the development, including the bio-filtration systems, habitable for the monarchs.
She added, "If they're done right the first time so we don't have to go back, not only will wildlife benefit and hopefully be retained, but also they won't have to spend extra money to recover them if invasive species take over."
Last year, Taylor pointed out, was bad news for the monarchs. Record temperatures in March forced the monarchs to move too far north. The summer heatwave also had what he calls a "tremendous" impact on the population.
He added that this year's weather patterns weren't great for the monarchs, either.
"I liken all of this to Goldilocks," he added. "Sometimes the porridge is too hot, sometimes too cold and sometimes just right. For the last year and a half, for monarchs, it hasn't been just right."
Hope through help
Agnew and Taylor are of the same mind that there is hope for the monarchs, provided humans chip in.
Taylor said the monarch population can bounce back from low numbers quickly due to their high reproductive rates. There hasn't been, according to NCNPA numbers, two consecutive years of noticeable monarch population decline since they started measuring the populations in 1994.
Agnew also is confident, and the Friends have ramped up their conservation efforts. Every Tuesday, an offshoot group affiliated with the friends — the Tuesday Teasel Taskforce — has been working on rooting out invasive teasel plants from the area. Now the group is meeting three times per week.
Taylor also works on saving the monarchs by distributing the butterfly's host plant, milkweed, and promoting the creation of monarch way stations, patches of land with nectar-rich plants that serve as a feeding spot for the butterflies on their migration to Mexico. While there are roughly 7,000 such registered sites in the U.S., Taylor said, there needed to be 7 million to 10 million before headway can be made.
There are 283 such way stations in Wisconsin, eight of which are in Wauwatosa.
"Monarchs are going to come back," Taylor said. "The question is when and how soon and what will it take to have them come back."
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