MARY LOUISE KELLY, HOST:
Monarch butterflies, like many other pollinators, are in trouble. Monarch populations have declined nearly 80 percent over the last two decades. NPR's Laurel Wamsley reports that scientists are looking for help in their own backyards.
LAUREL WAMSLEY, BYLINE: There are lots of reasons monarch populations are dropping.
ABIGAIL DERBY LEWIS: But the main force has been habitat loss.
WAMSLEY: That's Abigail Derby Lewis, a senior conservation ecologist at the Field Museum in Chicago. Monarchs are pollinators. They eat nectar from lots of different flowers. But there's one plant that monarchs can't live without - milkweed.
LEWIS: So milkweed is the only plant that females can lay their eggs on. Without milkweed, there are no monarchs.
WAMSLEY: And there's a lot less milkweed than there used to be. In the last 20 years, as the human population has grown, the marshy lands milkweed loves have been disappearing. So ecologists started looking for new places to plant it. Derby Lewis and her colleagues at the Field Museum turned to their own city.
LEWIS: Especially here in the Chicago land area, we're a swamp.
WAMSLEY: Perfect milkweed habitat. Monarchs migrate from central Mexico to the northern U.S. and Canada. Scientists looked at detailed images of four urban areas along a common migration path - Austin, Kansas City, Chicago and the Twin Cities - and looked for all of the potential plantable space for monarch habitat. Researchers found two things. One, there was way more milkweed already growing in cities than people thought.
LEWIS: I think cities have been written off as having zero milkweed, essentially. We found over 41 million stems of milkweed already on the ground in these four large metro areas.
WAMSLEY: And their other finding? That cities have the potential for so much more. In the Chicago metro region, for example, they think it's possible to double the amount of milkweed with the aid of locals. Planting more milkweed in cities doesn't just help monarchs. It helps all sorts of pollinators, wildlife species and even some grassland birds. Derby Lewis says the biggest opportunities for expanding urban monarch habitat is by people planting themselves in their own backyards or even on a balcony.
LEWIS: In many ways, if you plant it, they will come. It's a wonderful, almost-instant gratification that people feel and are empowered by in order to make a difference.
WAMSLEY: So if you'd like to help out some monarchs on their North American journey, consider planting some milkweed on whatever patch of land you've got. Fall is the perfect season to plant them. And by spring, you should have some bright orange visitors on your block. Laurel Wamsley, NPR News.
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