When it comes to ecosystem preservation, forests really get all of the love. Humans plant about two billion trees every year, many in an attempt to repair degraded ecosystems or help capture carbon dioxide out of the atmosphere. While planting the right trees in the right places can help to repair ecosystems and fight climate change, these tree-planting projects often end up displacing another important ecosystem—grasslands. About 26% of Earth’s land is covered by grasslands, making them the largest, most-threatened, and least-protected terrestrial ecosystems in the world. That land puts in a lot of work when it comes to making homes for species and removing carbon dioxide from the atmosphere. Grasslands store about 12% of all the carbon on land, and they have special traits that allow them to be more effective carbon sinks than forests in certain places. Grasslands store the carbon they capture underground in the soil, so little is exposed as foliage. Trees, meanwhile, transfer large amounts of carbon out of the soil as they construct their trunks and branches. This difference means that wildfires can cause forests to release literal tons of stored carbon into the atmosphere, while grasslands release little of their carbon stores when burned.
In the grasslands of central Mexico, high on rugged volcanic mountains, there lives a particularly adorable species of rabbit. It is the second-smallest rabbit in the world, with physiological traits and behaviors unlike any other species on Earth. Understanding its biology, as well as the unique challenges of protecting it from extinction, can help us to understand the importance of grassland ecosystems around the world and better inform us on how we can keep our planet healthy in the face of climate disasters. Consider: the Volcano Rabbit, Romerolagus diazi.
OH MY GOD THEY’RE SO CUTE!!! When people on the internet call cute things “smol beans”, these rabbits are what they are talking about. Volcano rabbits are quite small, weighing at most 600 grams (1.3 pounds). They’re roughly the size of an American football and weigh about the same (which makes me wonder how far I could throw one). Volcano rabbits are primitive species, meaning that their anatomy hasn’t changed as much as other types of rabbits over the millions of years they have existed. As such, volcano rabbits resemble rabbit precursors of the ancient past more than they resemble other rabbit species today. They have small, rounded ears and fairly short legs, making them considerably slower than other rabbit species. Their blended black-and-brown coat provides them with camouflage against the native grasslands and volcanic soils where they live.
These lovely little buddies can be found along a region of central Mexico known as the Transverse Neovolcanic Axis (which would be a great name for a heavy metal band). These mostly extinct volcanoes stretch across much of Central Mexico and are home to many species which can be found nowhere else on Earth. Over half of the mammal species endemic to Mexico can be found in this belt. Within this range, volcano rabbits can be found in subalpine grasslands and sparse pine forests between 3,000 and 3,600 meters (10,000 and 12,000 feet) above sea level. These grasslands have long growing seasons, with dry winters and long, wet summers. Volcano rabbits are intimately tied to these grasslands, so much so that their name in Nahuatl (Nah-wah-tl), the language of many indigenous people of central Mexico, “Zacatuche”, translates literally to “bundle-grass rabbit”.
The kinds of grasses that grow most densely in volcano rabbit territory are bunchgrasses known as Zacaton. These wiry grasses grow in clumps that can stretch up to 8 feet tall and make up the overwhelming majority of volcano rabbit diets, though the rabbits also sparingly eat tree bark and crops such as maize and oats. In addition to feeding the rabbits, zacaton helps protect them from their many predators. Considering volcano rabbits are pretty much rotisserie chickens with legs, lots of animals would love to eat them, including weasels, bobcats, and hawks. But you can’t catch what you can’t see, and zacaton grasses make for great blinds. Volcano rabbits will munch away at the softer, more tender blades of zacaton and use the older, wiry blades for cover. By carefully controlling the growth of the zacaton, volcano rabbits create channels through the grass which lead to their burrows, allowing the rabbits camouflage and fast access to safety should a predator decide it wants some conejo al ajillo . This clever ecosystem engineering makes up for how slow volcano rabbits are compared to other rabbit species.
Like many rabbit species, volcano rabbits live in colonies with strict social hierarchies. These colonies are much smaller than average, though, normally consisting of 2-5 individuals (though can you really call 2 rabbits a colony? Maybe it’s for tax purposes). Typically, a colony contains a dominant male and female, as well as several subordinate individuals who all work together to survive. Volcano rabbits communicate with a system of barks and squeaks, used most often to warn other members of the colony of predators. With the exception of pikas, Volcano rabbits are the only rabbit species in the world that vocalizes.
Breeding season typically occurs during the warm, rainy months between May and September, though the rabbits are capable of breeding year-round. In captivity, only dominant female volcano rabbits are allowed to breed. Like many animals, volcano rabbits use scent glands located in their groin and under their chin to signal their reproductive status to potential mates. Imagine having a patch of skin under your chin that smells like sex, and imagine that you find out if your partner is in the mood by sniffing their chin to see how much like sex it smells. This is what it’s like to be a volcano rabbit. Be grateful that humans have Hinge.
Gestation takes 40 days, after which point mother volcano rabbits give birth to between one and four kits. A volcano rabbit mother will typically have four to five litters per year. While that might seem like a lot of babies to have in a year, it doesn’t hold a candle to the kinds of feats of fertility that other rabbit species are capable of. Eastern cottontails, the rabbits most Americans are familiar with, can have up to a dozen kits per litter, and three to four litters per year. A single cottontail mother may give birth to 35 kits in a single year, while the best a volcano rabbit mother can do is 20. In other words, volcano rabbit mothers have basically no chance of getting their own reality show on Rabbit TLC.
Unfortunately, volcano rabbits are considered one of the most-endangered rabbit species in the world due their small and shrinking distribution limited to few volcanoes surrounding Mexico City, one of the largest metropolitan areas on Earth. As such, volcano rabbits struggle with habitat fragmentation and destruction due to human activity. Habitat fragmentation occurs when man-made structures, such as fences or roads, physically divide a species’ habitat. This can lead to individuals within a species having access to fewer possible mates, lowering the genetic diversity of the population. Low genetic diversity, then, can lead to populations becoming more susceptible to disease and generally less able to adapt to changes in their environments. Currently, volcano rabbits are split into 20 fragmented grasslands and pine forests occupying a total area of 335 square kilometers, about half the size of New York City.
Further threatening volcano rabbits is the destruction of zacaton grass itself. Many grasslands in central Mexico have been turned into agricultural land to grow potatoes and avocados. These agricultural fields not only displace the grasslands, but use massive amounts of agricultural chemicals such as pesticides and synthetic fertilizers, polluting the areas around them. Livestock often graze in volcano rabbit territory as well, and ranchers will sometimes intentionally start fires to encourage the growth of new, younger grass for their animals to eat. Fires are part of the natural dynamics of grasslands all over the world, but if they take place too frequently, they can destroy the grasses that volcano rabbits require for food and cover.
In other places, governments and NGOs have promoted planting trees in an attempt to capture carbon from the atmosphere or restore the ecosystem. Most natural forests in central Mexico contain about 250 trees per hectare, allowing ample space for grasses to grow between them. Frequently, though, forest management operations in the region plant trees at a density of over 2500 per hectare, ten times denser than is natural. This crowds out the grasses and increases the intensity of wildfires in the region, leading to further habitat destruction. This same overplanting of forests has occurred all over the world. Fortunately, forest management services in countries like the United States have realized the error of their ways and now strive to maintain forests at healthy, naturally-occurring densities.
Image credit: Jürgen Hoth. Examples of the zacaton grasslands in which volcano rabbits live. Note the sparse tree cover, with occasional patches of conifers interspersed with zacaton. You can practically imagine Elmer Fudd chasing Bugs Bunny across this scenic vista.
The destruction of central Mexico’s grasslands stretches beyond just the volcano rabbit. Mexico City, which sits square in the middle of the Transverse Neovolcanic Axis, is one of the largest cities in the world. Over 9 million people live in the city proper, and the surrounding metro area has a population of over 20 million. All of those people need water to survive and to perform basic necessities, but Mexico City is having a water crisis. While many cities acquire their water from local rivers, lakes, or reservoirs, Mexico City uses a series of underground aquifers. These aquifers are being depleted at such a rapid rate that the whole city is sinking–some urban areas up to a meter each year—as the ground beneath them dries and compresses. Already, citizens in and around Mexico City have to deal with regular water shortages, and there could come a day in the very near future where the aquifers beneath the city run dry or become so polluted by the heavy use of agricultural chemicals that they are no longer potable, leaving millions of people without access to clean water.
Many factors have contributed to Mexico City’s water crisis, from over-paving to a lack of sufficient wastewater treatment, but a major contributing factor is grassland displacement. We don’t always appreciate how much water trees can go through in a day, but it becomes apparent when you look at a place like Mexico City. Each tree, depending on the species, can draw up to 150 liters of water out of the ground each day as they pull it up through their roots and out of their leaves through the process of evapotranspiration. Each tree can be pictured like a straw, literally sucking the ground dry, and poor forest management has led to there being 10 times too many trees in some parts of central Mexico. Grasslands, meanwhile, use much less water than dense forest or agricultural land, so restoring them to their natural state will also help protect Mexico City’s diminishing water supply.
Ultimately, protecting the volcano rabbit isn’t just about protecting the volcano rabbit. These rabbits are so tied to their ecosystems that what protects the rabbit will also protect the grasslands. Protecting the grasslands, in turn, will help preserve Mexico City’s water supply and prevent a humanitarian crisis. Humans like to think that we are fundamentally separate from nature: we don’t see chipmunks or coyotes using iPhones or driving cars or drinking coffee, so obviously we are different from them. Examples like the volcano rabbit help to break down this false dichotomy. All living things need food, shelter, and drinking water, and those things all rely on a functional ecosystem to deliver them. When we burn the Amazon, we handicap our planet’s carbon cycle, leading to an increase in severe weather worldwide. When we blanket the ground of our urban areas with concrete, they flood and dry out due to an inability of the soil to soak up rainwater. Humans are nature, and acting like we aren’t only exacerbates the existential problems we face.
So what can we do to help protect the volcano rabbit? To answer this question, I reached out to Jürgen Hoth, who has been involved with the research and conservation of volcano rabbits since the 1980s. Over that time, Jürgen has worked to help raise awareness of the rabbit’s plight and the importance of grassland ecosystems not just in central Mexico, but around the world. In the past, Jürgen designed and helped to build the very first volcano rabbit enclosure at the Chapultepec Zoo in Mexico City, allowing the rabbits to breed in captivity and helping to raise awareness of the species to the people of Mexico City. Currently, Jürgen is working to enable the conservation work of indigenous Mexican communities living in the volcano rabbit region. In conjunction with Mexico’s Commission for Protected Areas (CONANP), Jürgen has helped build washrooms in the mountains to prevent human waste from polluting the forest and grasslands, and transform it into organic fertilizers to be used by local indigenous people to grow crops. Through CONANP’s work, we can all give a shit.
Jürgen has learned much by listening to indigenous people across North America. Forests managed by indigenous people in the US and in Mexico tend to be healthier, with a more natural density of trees, and have more land set aside for nature. In addition, indigenous people understand the importance of fire to keeping an ecosystem healthy. Periodic forest fires can actually help to keep forest and grassland ecosystems healthy, replenishing the soil and paving the way for new growth. In the Transverse Neovolcanic Axis, healthy burns tend to occur on a cycle of approximately 12 years. If these small fires are stopped, forests tend to become overgrown and litter accumulates, leading to larger, hotter, and more destructive fires like what has been seen in the American West. At the same time, fires that occur too frequently can damage the ecosystem, preventing the new growth that often comes after a fire.
“If you talk in terms of ecosystem services, it only makes sense to follow nature,” Jürgen says. “We need to learn to be humble and listen to indigenous people, like the ones who live here or on the reserves in the U.S.. We need to learn about ecosystems from the people who have learned by living in that ecosystem. That’s where our information should come from together with frontline research being carried out in this field .”
Across the world, major organizations have begun to give grasslands the recognition they deserve. In a recent victory, a team of scientists from around the world, including Jürgen and the government of Mongolia, have convinced the UN to designate 2026 the International Year of Rangelands and Pastoralists (IYRP). This initiative aims to draw attention to the importance of grassland conservation worldwide, with a special emphasis on how indigenous pastoral people can help protect these ecosystems. Over 102 countries worldwide support the IYRP, and organizations around the world hope to use the opportunity to raise funds for conservation work and direct policy towards more sustainable land use. Click here to learn more about the IYRP.
The volcano rabbit is a fascinating and adorable creature, but it’s so much more than that. Through understanding the volcano rabbit’s intimate relationship with its grassland environment, we can learn more about how to protect ecosystems across the world, from Mexico to Mongolia. Its plight highlights how much humans rely on nature, whether we like it or not. Through more responsible management of our forests and grasslands, and by understanding that not all of nature needs to be forests, we can protect not only the volcano rabbit, but animals all over the world, humans included.
Besides, who can say no to those cute wittle ears?!
I want to give a special thanks to Jürgen Hoth for helping with the research and fact-checking for this article, as well as for allowing me to use his beautiful photography.
Sources and More Information:
Hoth, J. and H. Granados, 1987 A Preliminary Report on the Breeding of the Volcano Rabbit (Romerolagus diazi) at the Chapultepec Zoo, Mexico City. International Zoo Yearbook. 26:261-265.
Hoth, J., et al., 1987. Volcano Rabbit- a Shrinking Distribution and a Threatened Habitat. Oryx. IUCN. 21 (2): 85-91.
Hunter et al., 2014. "Factors affecting the distribution and abundance of the Endangered volcano rabbit Romerolagus diazi on the Iztaccihuatl volcano, Mexico". Oryx.
Osuna, F., et al., 2020. Phylogeography of the Volcano Rabbit (Romerolagus diazi): the Evolutionary History of a Mountain Specialist Molded by the Climatic-Volcanism Interaction in the Central Mexican Highlands. Journal of Mammalian Evolution, 1-13. Published online 18 January, 2020
National Geographic Photo Ark
The Zoological Society of London: EDGE of Existence Program Survival Blueprint.
The Mexico City Water Crisis:
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