Veganism prohibits humans from exploiting and murdering animals in order to use their bodies as material goods, but there are still plenty of ways for humans to eliminate animals without a single amendment to the vegan constitution. Though most vegans wouldn’t want to do this, it would even be theoretically possible—problems of practicality aside—for a vegan humanity to get rid of almost every sentient animal on the planet other than humans without doing anything that veganism considers unethical.

Here are some of the weapons that vegans would have in their arsenal if for some reason they wanted to vanquish other animals and have the planet to themselves:

Birth control. Veganism does not prohibit the spaying and neutering of cats and dogs, as long as it’s done while they are anesthetized. If we did that to every cat and dog in the world—a goal that would be perfectly compatible with veganism—we could end cats and dogs. But why stop there? If vegans have no moral qualm with removing the reproductive organs of domesticated animals, how can they object to doing something similar to wild animals? It’s not as if wild animals have more rights than domesticated animals, is it? (And if they do, does that make it okay for us to eat meat as long as it’s from domesticated animals?) 

Wild animal birth control is improving all the time; one way to fiddle with the fertility of other animals is through contraceptive injections that last for five years. You have to sedate the animals first, but hopefully this can be done in a way that isn’t much more traumatizing than taking a dog or cat to the vet.

Vegans might still insist that there is a difference between sterilizing our dogs and cats and desexualizing every wild animal we find. We are responsible for our pets because they are under our care, and part of this responsibility means taking some paternalistic measures like cutting out their testicles or ovaries for their own good, or for our convenience, or to prevent the suffering of future dogs and cats in a world already saturated with devoted animal companions. 

Point taken, but then are vegans okay with abandoning wild animal birth control in every situation at all costs? Because my understanding is that vegans support contraception on wild animals when humans decide that their numbers need to decrease one way or another. If it’s not a rights violation to sterilize animals without their consent when their population is creeping up (which many think it would be if done to humans), how does it become one if their numbers are relatively stable? If vegans are okay with humans reducing wild animal birth rates on the grounds that later generations of these animals will suffer if the competition to survive on dwindling resources is fierce, they have no reason to ignore that even animals born into food-rich environments experience plenty of suffering that could have been eliminated if their parents had only had a copule shots of GonaCon.

If humans decided it would be for the best to knock other species out of existence, veganism couldn’t stop them, as long as they phased the animals out rather than killing them outright.

Self-defense. If other animals are threatening humans with bodily harm, vegans usually say it is okay to kill them. This won’t help vegans kill the peacenik herbivores who would rather run from them than eat them, but could come in handy against the violent, uppity ones.

This is even more true if the herbivores have already disappeared thanks to humans removing their ability to reproduce. Bears and wolves often prefer to leave humans alone, but phase out a large portion of their food supply and we might start looking like bipedal venison to that sharp-toothed lot. Whether they come salivating to our cities or vegans camp amongst them, well-armed vegans would have the chance to take out a few carnivores without going against their ethics. They just better keep their Smith & Wessons in faux leather holsters.

Violently competing with other animals for plants. Veganism discourages us from seeing animals as food, but is okay with us killing animals who dare get in the way of our food. This gives vegans many opportunities to destroy other animals. Though vegans would rather avoid poisoning or shooting vertebrates who venture onto human croplands—preferring to keep them from loitering near the crops in the first place—veganism sighs and shrugs if doing so turns out to be “necessary.” As we saw in the self-defense example, vegans do approve of animal killing if it can be framed in some sort of human self-preservation sort of way, and most vegans consider guarding human food supplies to be close enough.

This “human food comes before animal lives” allowance in veganism mostly permits the veganism-approved killing of land animals, but it could be used to kill marine animals too, since humans sometimes compete with herbivorous fish for wild algae. Under veganism, it could be curtains for any non-human pest that wanders too close to a kelp forest, if that seaweed is destined to become human food, supplements or fertilizer. 

Habitat destruction/fragmentation. People who specialize in this sort of thing name habitat destruction and fragmentation as the leading threat to wild animals. For instance, the International Union for Conservation of Nature says:

Analyses of the data on threats to bird, mammal and amphibian species evaluated for the 2004 IUCN Red List show that the most pervasive threat that they face is habitat destruction and degradation driven by agricultural and forestry activities.

In Essentials of Conservation Biology, Richard B. Primack writes:

Habitat destruction is an important cause of known extinctions. As deforestation proceeds in tropical forests, this promises to become the cause of mass extinctions caused by human activity. All species have specific food and habitat needs. The more specific these needs and localized the habitat, the greater the vulnerability of species to loss of habitat to agricultural land, livestock, roads and cities. In the future, the only species that survive are likely to be those whose habitats are highly protected, or whose habitat corresponds to the degraded state associated with human activity (human commensals).

In “The Human Footprint and the Last of the Wild,” Eric W. Sanderson, Malanding Jaiteh, Marc A. Levy, Kent H. Redford, Antoinette V. Wannebo and Gillian Woolmer write:  

Called the single greatest threat to biological diversity, land transformation has resulted in loss and fragmentation of habitat in many different ecosystem types (Vitousek 1997). Moreover, fragmentation often facilitates additional negative consequences to species and ecosystems beyond the simple loss of habitat, in concert with other processes and over time (Crooks and Soulé 1999, Laurance and Cochrane 2001). … For most ecosystems, the greatest near-term threats are from direct human activities like those measured by the human footprint: transformation of land for agriculture and for suburban and urban development, direct effects of roads and indirect effects of the access that roads afford, a power infrastructure that not only pollutes and modifies the climate but also enables extensive land transformation and road construction, and, ultimately, greater consumption of resources by an increasing human population.

In “Causes and Consequences of Species Extinctions,” Navjot S. Sodhi, Barry W. Brook and Corey J.A. Bradshaw claim:

Although extinctions are a normal part of evolution, human modifications to the planet in the last few centuries, and perhaps even millennia, have greatly accelerated the rate at which extinctions occur. Habitat loss remains the main driver of extinctions, but it may act synergistically with other drivers such as over-harvesting and pollution, and, in the future, climate change. Large-bodied species, rare species, and habitat specialists are particularly prone to extinction as a result of rapid human modifications of the planet. Extinctions can disrupt vital ecological processes such as pollination and seed dispersal, leading to cascading losses, ecosystem collapse, and a higher extinction rate overall.

In Sparing Nature: The Conflict Between Human Population Growth and Earth’s Biodiversity, Jeffrey K. McKee writes:

Nature’s great restrictive law has been in evidence since the beginning of agriculture. As we take up more land, water and energy to produce our food, little is left for other species. At our current rate of agricultural expansion, it is estimated that by 2050 the worldwide amount of natural ecosystems converted to farms and pastures would total an area larger than the United States. Because we take this land bit by bit across the globe, what is left for other species and small and widely dispersed patches of land.
If every human were given an equal share of the land—their stadium-size piece from our thought experiment—it would be difficult to get sufficient resources for sustenance and sustainability without agriculture. A forager would have to range beyond the boundaries to continue living. But this is in effect what has happened to many other species, for their resources are not evenly distributed either, and often they must travel far to get them. Yes, we set aside lands for them to live in, parks and reserves, but for many wide-ranging species this is not enough. Their habitats have been fragmented, and they don’t have agriculture or any other means to focus ecological energy on producing the resources they need. …
The problem of habitat loss is compounded by habitat fragmentation—dividing up species’ ranges into patches, interspersed with environments that are less hospitable or even dangerous. This happens when roads are built, logging tracts are cut, agricultural lands expand, suburbs sprawl, rivers are dammed, and so on—the list is endless. Lifeways that have evolved over millions of years get cramped in tight spaces, and sustaining a wild population becomes difficult if not impossible. (114-115)
Will conservation keep us out of the woods in terms of biodiversity loss? No. … [Guy Cowlishaw of the Zoological Society of London] found an ‘extinction debt’ for 30 percent of the primates in each country studied. In other words, populations were on the decline and could be expected to go extinct over the course of the next few decades—with or without conservation efforts to prevent hunting or further habitat loss. Hunting would accelerate the eventual extinctions, but none of the species was in danger from hunting alone. Habitat loss and fragmentation were the main culprits. The human wedge has come between interbreeding populations of once widespread primates, diminishing their chances to perpetuate future generations. (119)

And New Zealand Biodiversity says, “For most native species, the destruction of their habitat is a worse threat than hunting by humans – hunting targets a few individual animals, but losing their habitat affects all species in an area.”

In animal rights veganism, animals have the right to their bodies, products of their bodies and their lives, but little else. Most notably, they do not own their homes. You think birds and gophers have deeds for those twigs they threw together or that hole they mindlessly dug in the ground? Please. The property rights of animals under veganism are basically nil. If humans want land for any reason other than animal exploitation or consumption, veganism does not forbid humans from taking this land, no matter how many other animals die so humans can spread out a little more. If we want to divert water to drip it over our corn, that’s cool with veganism, even if it kills fish. Sucks for Nemo, but hey, we’re not killing them to eat them, so what’ve they got to complain about?

As far as veganism is concerned, there is no limit to the number of forests we can fell to plant soybeans, so long as we feed those soybeans to ourselves instead of to cattle. Vegans like to point out that grain-fed animal agriculture demands even more land than getting an equivalent amount of calories or protein from eating grains directly, but this is one of those differences in degree rather than kind. There is nothing in veganism to stop a vegan world from taking over even more land for human use than we have already.

Human expansion is, in effect, a scorched earth policy against almost all of the other lifeforms in the world. It’s a more effective way to kill other animals than eating and wearing them, and yet veganism has nothing definite to say against it. Combine that with forced birth control on other animals, as well as self-defense and killing animals in the competition for plant foods and a vegan world could be just us and the algae.