Forget all those alarm calls. It turns out that the monarch butterfly isn’t endangered after all. Now we can all just stop worrying, right?
Just over a year ago, the International Union for Conservation of Nature (IUCN) designated the monarch as “endangered.” But at the beginning of this month, the organization reversed that decision. Instead, it placed the monarch one step closer to the safe zone, in the “vulnerable” category.
The confusion over the species’ status stems from disagreements among scientists about which mathematical population model is best for projecting the population’s numbers. The assessment that led to the endangered designation was based on a linear population model.
But sometime around 2014, what had been a rapid decline shifted to something different: maybe a slower decline, maybe a plateau – maybe even a slight increase. That’s led some researchers to suggest that another, more complicated model may be a better fit. Some of those researchers made that argument to the IUCN, suggesting that the endangered designation had been too hasty. Ultimately, the IUCN agreed.
There’s actually quite a wide range of opinion among scientists as to the level of danger the migratory monarch’s current population signifies. Some speculate that the higher populations of decades ago may have been an historical anomaly, with forest clearing for agriculture having opened up much more habitat for the species than had previously been available.
The more recent decline, these researchers suggest, is just the butterflies’ response to the reversion of many acres to woodland (see another article in this issue for more on that). Others, though, point out that even if that’s true, the current monarch population may still be so small that a single adverse event – drought, cold snap, and so on – at the wrong time could still be enough to send the species into extinction.
It should come as good news, contrary to this month’s theme of scary trends, that the monarchs are farther from extinction than previously thought. Perhaps what’s truly frightening about the monarch’s case is how little scientific consensus there is about how close the species really is to endangerment or extinction. In the meantime, let’s play it safe, and keep planting milkweed!