Aside from the charismatic fauna thing
Monarch butterflies are really cool. They’re big, with those hi-contrast unmistakable wings and robust bodies that are velvety black with bright white spots. They fly around people’s gardens and farms, being conspicuous, and their caterpillars are big shocking alien things unconcerned with people. Monarch chrysalises are bright green jewels with shimmery gold spots. Kids love them. My kids love them. Old people from the American Midwest remember loving them when they were kids. So there’s all that.
Apart from all that, though, the Monarch speaks our ecology to us every winter. As things cool down in early Fall, our Monarchs obey an odd hardwired compass and head South. But not just South - thousands of miles, to a specific oyamel fir forest in Michoacan. We get a rough count of them by measuring how much space the returned Monarchs take up.
This gives us a concise annual report of our continent. Not many of us are aware of how radically we’ve re-shaped the ecology of the Great Plains, arguably most dramatically in the last 30 years since the advent of Monsanto’s demonically effective herbicide Round-Up (aka glyphosate). It’s hard to see the vast whole. But the Monarch shows it, in a sense, by gathering its remnants in a single place for us to see every year.
The Monarch is in steep decline, probably teetering on the edge of extirpation in North America. At some point it’ll reach a tipping point, and future generations of Americans will grow up without it.
That all sounds glum and melodramatic. Well, so be it. Dispassionately, it’s an interesting thing to study.