Intro to Rewilding: George Monbiot
Just in case you are not acquainted with “rewilding,” the best introduction I know is a short video with George Monbiot below. Actually I was introduced to Monbiot by the audio of this talk on NPR about ten years ago. The video adds a couple of dimensions, but it might detract from the enthusiasm in Monbiot’s voice. (His enthusiasm is contagious, so if you are looking for a contagion to improve on COVID and flu, a listen here could lift your spirits.) He relates a snippet of his personal journey and expands the view to a planetary scale. If you’ve already heard it, you might still enjoy another go. Check it out:
NEXT: To see what an effort rewilding a significant portion of our planet’s land will take, we have to look at what humans have already seized, largely in the form of agriculture.
The landuse challenge, by the numbers
In Our World in Data, Hannah Ritchie reports that almost half of the world’s habitable land (land not covered by glaciers and deserts) is used for agriculture. A thousand years ago, roughly 4 million square kilometers—less than 4% of habitable land—was used. Now that’s up to 48 million out of 106 million square kilometers: 45%.
If you like data visualizations, you’ll salivate over what you will see in Ritchie’s report. The blurry image below is the best I could insert here—but you get the idea. If you zoom in enough, you might be able to read it.
Nonwild territory has to be understood not just in sheer aggregate area, but in terms of fragmentation of habitat. The map of development in Brazil below indicates how land clearing, principally for cattle grazing, carves up the Amazon rainforest.
If you zoom way in on the almost vertical line of red close to the center of the map of Brazil, you can see the typical “herring bone” pattern of how deforestation starts. There’s a main road with roads branching off at right angles, and more roads branching off of them.
Towards the lower left there is a massive swath of complete deforestation in the state of Rondonia. That represents the filling-in and reconnecting of many “herring bones” that existed in the 1990s. I know this because I helped map deforestation in Rondonia using Landsat imagery back in the 1990s at the University of Maryland. A lot of what you see in that swath of red were once linear features such as roads and logging tracks, mainly for agriculture, now filled in. Sorry the image is so blurry, but I do not have time to sort through zillions of Landsat images in a huge government library.
Habitat fragmentation of Amazon rainforest is obviously devastating. Not so obvious is the kind of habitat fragmentation going on all around us. Natural production of food and energy in temperate habitat is not as intense as in a tropical rainforest, but it is not nothing. Any road map of the eastern U.S. going down to the secondary street level indicates just how fragmented our native forest habitat has become. Add the tertiary level—cul-de-sacs—it becomes still more fragmented. There’s a proverb that before colonization by white folks, a squirrel could travel from Cape Cod to the shores of the Mississippi without ever touching the ground. That’s quite possibly the literal truth. It would take a lot of rewilding to restore that squirrel’s path. Every stretch of pavement removes a portion of a tree-by-tree route.
Yes, we have parks, refuges, and reserves, but most of them are scattered in a way that fails to create the kind of large expanses of contiguous habitat required by both animals and plants if they are to remain diverse, robust, and resilient. Particularly the kind of habitat to support a viable population of apex predators.
That’s what brings us to the idea of restoring a healthy population of jaguars in the U.S. Does it make sense? Is it a good use of resources already stretched thin with efforts to counter the effects of natural habitat destruction and fragmentation?
Jaguars: charismatic, and agents of diversity
Let’s face it: large cats have a charisma that’s hard to beat, despite how horrifically they treat their prey. Like all big cats, jaguars are beautiful and powerful. And they are big—third from the top, after tigers and lions. They weigh up to 125 kilograms—275 pounds, about 25% more than the weight of the largest cougars. They are solitary stealth hunters, seldom seen in the wild. They ambush their prey. If you are trotting along on singletrack in the Amazon near a jaguar who wants to make a feast of you, by the time you see it, it will be too late.
According to an article by Erin McCormick in The Guardian that appeared on December 28, there is only one—yes, one—jaguar known to live in the United States, in Arizona. Photo: Brian Sedgbeer | Dreamstime.com
South of Arizona’s southern border, per McCormick, there remains: “A small, struggling population living in northern Mexico near the border and the sleek, long-tailed cats have been known to wander north into the US. But this population has little genetic diversity and faces its own risks of extinction.”
What’s worse, portions of a border wall between Arizona and Mexico obstruct the north-south flow of wildlife, including jaguars. To read more about the crime of “protecting” borders, see what I wrote about border walls and immigration policies here.
So now the Center for Biological Diversity (CBD) has called for the federal government to reintroduce jaguars into the U.S. and increase protection for their habitat. They have petitioned the US Fish and Wildlife Service to create an experimental population of jaguars in the Gila national forest, a sprawling, rugged 3m-acre wilderness in New Mexico dotted with pinyon pines. They also called for additional protections for millions of acres of wild lands in New Mexico and Arizona.
They are actually aiming for a population of 90-150 jaguars in the U.S. That number was proposed by Eric Sanderson of the Wildlife Conservation Society as achievable in the U.S. desert Southwest. Awesome. Needless to say, the New Mexico Cattle Growers’ Association called such a scenario a “death warrant” for rural populations in the region. (What might come to mind as we consider land for grazing cattle is Hannah Ritchie’s call for revamping our food system to cut the enormous inefficiencies in a calories-per-unit-area calculus arising from cattle grazing. I linked to Ritchie above in connection with stats on landuse, but did not then mention her recommendations on food and agriculture practice and policy which make a hell of a lot of sense).
Here’s the pitch by the CBD (the “sole jaguar” referred to in the quote is a male called “Sombra” whose range is in southern Arizona):
Jaguars evolved in North America eons ago and lived here until people killed them off for their beautiful pelts and to eliminate a threat to livestock. . . . Over 50 years since the jaguar was placed on the endangered species list, we should not be facing the realistic prospect that this sole jaguar in Arizona will be the last.”
Sounds a lot like “rewilding,” doesn’t it? In fact, there is a jaguar restoration project going on right now in Argentina, described by our friend George Monbiot here. Following through has been difficult, largely because of the devastation of the native habitat.
At least the population of jaguars in all of the Americas is not currently threatened. I hunted for some reliable numbers of living individuals and estimates range widely, from 60,000 to 250,000. It’s probably about 170,000, which is what you find in the San Diego Zoo Wildlife Alliance Library: 163,000 in South America and 10,000 in Mexico. The bulk of the South American population is in the Amazon Basin. The bulk of the Mexican population is presumably in the south. .
Why protect jaguars, besides that they’re beautiful, enigmatic, and powerful enough to rip your throat out in a matter of seconds? If top predators is what we want, why not rely on cougars, who seem to have adapted relatively well to incursions by human beings in North America, as jaguars have not. Since they’re smaller than jaguars, they should get by with less area per individual, while keeping down the population of animals we don’t want too many of such as rodents and deer.
The historical case for bringing back the jaguar strikes one as a wee bit sentimental.
However: up to this point, we haven’t yet discussed the role that jaguars have as agents of diversity, which is the basis of the argument by the Center for Biological Diversity. It’s risky to depend on one top predator, such as cougars, to keep an ecological balance. What if—we’ve seen plenty of this in recent memory in epidemics hitting bats, birds, amphibians, and so forth, as well as human victims of COVID-19—an epidemic raged through the cougar population, but had little impact on jaguars? Isn’t it worth keeping jaguars around, just to cut the risk of hollowing out the apex predator layer altogether?
The problem is in numbers and in future of drought
I hate to throw a wet blanket over the petition by the CBD, but it doesn’t look to me like the numbers add up—particularly in the American desert Southwest, which appears to be getting progressively drier decade by decade, reducing its carrying capacity. Currently it is experiencing the worst drought in 1,200 years. Will it continue, or worsen? The quantity of wildlife it may have supported in the past cannot be relied on to predict what it will support in an increasingly grim future.
How much area do we need to support a population of 90+ jaguars? I have no data on jaguars, but male mountain lions—a third less the size of jaguars—are said by the USDA to have a range of more than 100 square miles, and females 20-60 square miles.
Based on weight, a jaguar male may have a geographic range of more than 120 square miles in the kind of terrain mountain lions frequent. I believe those two habitats are fairly similar. I was unable to find the typical range for jaguars north of the Mexican border, and any based on Amazon rainforest habitat, with its abundance of food, would be an underestimate.
Since the petition by the CBD calls for 3 million acres to start with in New Mexico, I will try to convert the foregoing numbers into acres rather than square kilometers, hectares, or square miles. Eventually we back out again to bigger units to be able to visualize the area.
So. There are 640 acres in a square mile. If our hypothetical male jaguar needs a range of 120 square miles, we have a requirement of 76,800 acres per individual male. Presumably somewhat less for a female. Three million acres divided by 76,800 is 39 males. Suppose female jaguars, like mountain lions, have a 40% less area requirement then males, or 46,080 acres. Then to have an equal number of males and females in the three million acres, the algebra tells us we would have 24 males and 24 females = 48 individuals. (I actually got only 2.949 million acres but rounding will have to take place somewhere. We don’t have partial individuals.)
Converting back to miles for the sake of visualization at scale, the size is 4,687 square miles, which calls for a square 68 miles on a side, or a circle with a radius of 38 miles.
This sounds very doable—starting with 48 individuals in the New Mexico reserve alone we are more than halfway to the target of at least 90 individuals over the entire area. They are asking for millions more acres in New Mexico and Arizona to be protected. If that works out to the satisfaction of various claimants to the land, and enforcement backs up laws and regulations designed to protect the area, there appears to be a fighting chance
But in reality, we will not have neat cells lined up in a compact array of 68 x 68 miles on a side, with 76,800 acres per each male and 46,080 acres per each female, each with the same resources. The Gila National Forest, as you will see on this web page, is hardly compact. It’s not quite as irregular as many a gerrymandered Congressional District, but its shape means that the perimeter is way longer than 272 miles (68 x 4), meaning it is more difficult to patrol—to keep the jaguars in and bad human actors out. There are more opportunities for interactions with people who may not be happy with the protected area—like a trophy hunter, a pelt poacher, or a cattle rancher who may shoot a jaguar who strays close to or outside the boundary. There’s also a piece of it on the south separated from the main block.
Availability of water will not be uniform, and there will be competition for water and other non-uniformly distributed resources, to the advantage of bigger and stronger or more aggressive individuals, both males and females. Some individuals will die of thirst, starve or be crippled by competitors or the vicissitudes of Nature.
I sought in vain on the web for anything definitive about the geographic distribution of mating pairs. Is it realistic to have an equal number of males and females? What is an optimum ratio? Should we assume that a particularly strong male will mate with multiple females? How many? (Some wildlife expert out there has a lot better answers than what has popped up on the web for me—maybe you know someone?) With just 24 males and 24 females in the population, genetic diversity is at risk—hence the minimum of 9o individuals the CBD aims for.
All in all, I’m hopeful for the creation of a protected area to bring back jaguars to the U.S. if it can be made to work. But I’m a bit dubious about the practicality, and I worry about the long-term outlook if this drought persists for many decades. It could cause the collapse of the jaguar population unless humans intervene, like a rancher trucking in water for his cattle . . . and that would defeat the whole purpose of rewilding. Is there some other, less risky project the Center for Biological Diversity should be working on?