How HIPPOs cause species extinction

Did you realize most of the species that are currently threatened with extinction reached this status because of hippos? This is true, but not because of actions from hippo the animal (which is currently listed as vulnerable to extinction itself) but rather due to HIPPO the acronym.

In environmental science, HIPPO is an often-used acronym used to highlight the most common reasons for biodiversity decline caused by human actions. The acronym breaks down like this:
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• H = Habitat disruption and transformation
• I = Introduction of invasive species
• P = Pollution
• P = Population expansion (human)
• O = Overhunting & overharvesting

This acronym is useful because it keeps its focus on species present in a particular location and shows how various human actions cause their populations to decline. To fully appreciate how human actions cause extinction, it’s best to do so starting from the perspective of the species that are being lost. Here’s a brief description of each letter.

Habitat disruption. While other species have the ability to transform their habitat (I’m looking at you, beavers), no species comes anywhere near the ability possessed by humans. Humans have been transforming their habitat since prehistoric times with the assistance of fire and primitive cutting tools. But this ability ramped up rapidly after the industrial revolution and the advancement of fuel-driven machines. We can now clear large forests in days, drain wetlands, gouge enormous holes in the ground for mining and even cut the tops off small mountains. No species living in an area humans want to transform has the ability to defend their home from that takeover. As such, protecting species that live in these areas from extinction requires human understanding, constraint, and active protection.

Invasive species. Species that live in places that has been undisturbed for a long time have all the tools and abilities (adaptations) they need to successfully survive challenges presented by the other species that live there. However, if a new species is brought in from another part of the world and plopped down suddenly into that location, the local species may find themselves unprepared to compete with or defend themselves from the new intruder. Prior to humans building boats and other vehicles to help cross large barriers, these introduction events were rather uncommon. Now human assisted introduction of invasive species is very common and has resulted in population decline and extinction of local species around the world. One example of this is the bilby, whose once large population across Australia has been reduced to near extinction due to the introduction of rabbits, foxes, and cats by European settlers (you can learn more about the bilby’s story here). To protect local species from introduced invasive species, we need to be very careful about transporting these invaders and try to eradicate them if they have already been introduced (not an easy or pleasant task!).


Pollution. We can’t deny it; humans are messy. We bring large amounts of materials into our homes to sustain our lives and dispose of these items when they get damaged or otherwise lose value to us. All this stuff has a manufacturing history that itself involves generation of waste that gets discarded into the environment. All this waste is called pollution and human activities result in the polluting of the land, water and air around us. Some of this pollution can affect the health of other species that live in or around areas where these wastes are disposed. Pesticides and fertilizers from agriculture, chemical waste from mining and other industries and plastic waste from all over are threatening our friends’ survival. To reduce the impact of pollution we need to reduce our reliance on disposable items and use durable items instead, repair and reuse items rather than replace them, and support research on the impact of pollution and development of safer alternatives.

Population. The Earth is really big, but it does have limits, and when it comes to life Earth can support a limited amount of living creatures. Due to the fact that all living things are continuously trying to increase their populations, the Earth winds up containing close to the max of how many living things can be supported at any given time. So, if one species finds a way to increase its population, this will typically be balanced by a decline in the populations of other species whose resources are now being used to support the growth of the species whose population is growing. The human population has been increasing rapidly since the mid-1700s thanks to the advancement in technologies. This growth has required taking resources away from other species and using them support a continuously growing human population. The rate at which the human population is growing has slowed in recent decades and is predicted to peak sometime this century somewhere in the range of 10 billion people. That’s 10 billion human consumers, and how much of the world’s resources are left to support to support the lives of the Earth’s other animal will depend on how conservative we are with those resources and how willing we are to share these resources with them.

Overhunting & Overharvesting. Humans aren’t the biggest, strongest, or most ferocious predator on the planet. But we are the most clever, and by way of our cleverness we have developed tools that have made us the most effective predator the world has ever seen. Whales and elephants used to be relatively safe from predation due to their being too big to bring down. Now their large size just makes them easier to find and humans can pick them off at will. Our “super-predator” status has put species that we like to hunt for their meat or valued parts at risk of being hunted to extinction. Indeed, human history has many examples of species that are no longer with us due to human hunting. The passenger pigeon in America, the thylacine in Australia, the quagga of southern Africa, and the Caribbean monk seal are among the many species that are now extinct due to human hunting. Fortunately, the relationship between hunting and extinction is now obvious and numerous laws have been passed to protect endangered species from being hunted. Diligent monitoring and enforcement of these laws is needed to keep valued species from being hunted to extinction. We can also help by changing our attitudes so that their meat and parts are no longer valued.

So, that’s how hippos are causing species extinction. Let’s use this understanding to find ways that we can share our planet’s resources with the rest of biodiversity so that we can all have a safe and supportive home.

​By Rick Martin

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