Amending the Endangered Species Act might help save the monarch butterfly

The Endangered Species Act (ESA) has not been amended since 2008. However, between 1973 and the late 1980s, amendments to and re-authorization of the law was relatively routine. In the past, Congress could take advantage of new science and new insights from the previous few years of implementing the law and build better policies. However, since then, extreme partisanship around the law has diminished the return on investment for any members of Congress or president who would seek to negotiate the compromises to make passage of an updated law possible. The last big failed bipartisan pushes for significant reform were led by Senator Kempthorne in 1997, Senator Chafee in 1999 and Representatives George Miller and Frank Pallone in 2002.

Congress has even had difficulty passing minor amendments to the law, with some opponents arguing that Congress can't be trusted to just make small changes, once a law is opened (like Pandora's Box). That premise is silly in any case, and as an example, a provision passed in the Bipartsian Budget Act of 2018 (section 20201) instructing the Department of Commerce to issue a waiver for an important coastal restoration project from requirements of the related Marine Mammal Protection Act shows that it is clearly possible for Congress to reach tacit agreement that allows modest changes to bedrock environmental laws.

So, what about the monarch butterfly?

The west coast population has declined by 99% since the 1980s (see Xerces Society graphic below). Fewer than 2,000 butterflies were counted in California this winter - that is an extremely low population for an invertebrate. Meanwhile the eastern population of monarchs that winters in the mountains of Mexico is still above its population size from the 2012-2014 years (yet way below historic numbers).

The population on the west coast clearly faces an extremely high likelihood of extirpation - i.e., it is hard to imagine there is a scientist out there who wouldn't agree that many already-listed endangered species are less endangered than western monarchs. It's decline hasn't stopped, and we have little idea of which threats need to be reduced, and by how much, to turn it around.

The population in the east has clearly declined, but one could argue its either threatened or endangered or maybe neither - there are still tens of millions of monarchs across the eastern part of the country. The population precipitously declined through 2009-2015 but was about 80% bigger in the last 6 years than the previous six at Mexican wintering forests.

Regardless of how at risk the eastern population is, the risk appears vastly different in magnitude and trajectory from the western population.

The Endangered Species Act treats invertebrates like butterflies differently

If the monarch had a spine, government scientists would be able to separately consider whether and how to protect these two populations. For example, there are 11 populations of green sea turtle each separately protected by the Endangered Species Act: 3 are endangered and 8 threatened.

However, Congress did not authorize the U.S. Fish and Wildlife Service to be able to consider separate listings of different populations for invertebrates. The definition of species reads: "species includes any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature."

Without a change in that limitation, the agency can't consider listing one population but not the other. 

If it lists the whole species as endangered it can’t protect western and eastern butterflies differently. Non-native populations of the butterfly in Fiji, Hawaii and Australia (where they are called ‘flying weeds’) would also automatically get protected under an endangered listing. If it does this, the agency might just ignore huge numbers of actions that harm monarchs except for ones that it thinks are important or that other parties petition it to regulate and enforce. Not a great outcome.

Or the agency can ignore the status of the 2,000 remaining isolated western butterflies and call all monarch butterflies threatened and write a special rule that allows some harms to happen for eastern populations but not for western ones. 

If I had to make a bet on what the agency will do, a global threatened listing would be my bet, for the reasons described below. 

Why does it matter?

A threatened listing allows the agency to issue a special rule that clarifies what kind of harms to species are allowed and which are illegal. More limited restrictions would be important in the east, where millions of monarchs roam across millions of acres of farmland, millions of miles of roads, and thousands of backyards where they are routinely - and accidentally - killed, but also where children and adults collect and rear caterpillars (conflict of interest alert: my mother rears and releases small numbers of monarchs easy summer). Under a threatened listing, protections can be customized to limit only actions that are strongly tied to population decline.

If they make this choice, the agency probably faces litigation based on the claim that the west coast is a 'significant portion of the range' of the species and the ESA requires the agency to provide the protection level needed for that portion to the whole species. If the western population soon vanishes under a threatened listing, it’s a little hard to explain how the science somehow shows it wasn't endangered in the first place. 

So, expect one more set of litigation around one more species of at-risk wildlife. 

If the agency wins in court, it’s a sad day for conservation science if somehow a population that numbered in the millions as recently as the 1980s, and its place in the ecosystems of the west coast doesn't make it ecologically or evolutionarily 'significant.'

And if the agency loses, then their only choice would be to list the whole species as endangered, with no special rules that allow accidental harms from things like cars killing them on highways, kids in backyards, and farming. 

These widespread restrictions would matter because they trigger paperwork, mitigation costs, and social costs on human activities. Where those restrictions fall on actions that cause harm but are only minor threats (like cars killing monarchs on highways or children raising caterpillars) those costs come at little or no conservation benefit. And the agency staff time they take takes away from time and money that would have been invested in other endangered species.

A policy option - for Congress

An option for Congress - one I believe they should take - is to put into law a waiver like they did in 2018 for the Marine Mammal Act, as in "the Secretary of Interior may separately consider a western population and an eastern population of the monarch butterfly in any determination made under section 4 of the Endangered Species Act and may make a separate determination as to whether the western and eastern populations of monarch butterflies are an endangered species or a threatened species."

Another option that Congress could take is to amend the definition of 'species' itself in the Endangered Species Act, as in "species includes any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature or of the monarch butterfly." 

The monarch is a relatively rare invertebrate with nearly a national range. And it is important enough as a cultural, spiritual, and ecological icon to all Americans to warrant giving it special consideration in the law so the government can better follow where conservation science leads it. And if listing is warranted, it’s a better outcome for other species, taxpayers, and various sectors of the economy to be able to target conservation where it will be effective in saving this special species of American butterfly.