In this post we’ll discuss worldbuilding the warm horizon-stretching savannas, where savannas can be found across an earth-like planet, and how to create the unique flora and migratory herds that can be found within their ecosystems.

Hey everyone, my name is Matthew, at least during the wet season, and this discussion is part of a series where I will be going through a science-adjacent worldbuilding process step-by-step. Last time we looked at worldbuilding rainforests, establishing the humid climates that dominate the equatorial zones. If you missed that video the link should be… here.

For today’s discussion, we’re going to be worldbuilding savannas, which are the iconic and expansive grasslands of the tropics that everyone knows from movies like The Lion King. We’ll take a look at their geography, before moving on to discuss their iconic flora and fauna, and how to worldbuild some of your own.

Savannas, according to the Koppen Climate Classification system, are classified as tropical areas with a significant dry season, but that do experience at least some rainfall in the wet season, which is usually the summer, bringing 500-1,000mm across the season. This rainfall allows for flora and fauna to be present, but outside of wet seasons, drought can ensue for lengthy periods, and most flora and fauna are required to be drought resistant to survive. These droughts make conditions exceptionally dry, which makes savannas prone to wildfires, and in periods where there has been less rain across the wet season, these wildfires can be truly devastating to the wildlife of the savanna.

Savannas are often tree-studded grasslands in contrast with their more jungled tropical rainforest counterparts towards the equator. Between savannas and tropical rainforests, an intermediate transitionary climate called a ‘monsoon’ climate exists, and the following equation is used to determine whether a zone is a savanna or a monsoon climate. Generally speaking, monsoons are areas that are too dry to be tropical rainforest, but not dry enough to be considered savanna.

This is the map of our fictional world of Locus that we’re creating throughout this series. As you can see, we’ve already placed our tropical rainforests down from our last video. Savannas then are the next band polewards after tropical rainforests, starting from around 5 degrees north and south to around 20 degrees north and south, extending a little further out to 25 degrees in areas that have a warm current off the coast. Something like… this. Regardless of if your planet is warmer or colder, your savannas will still be in the same area, but are probably going to be eaten into by rainforests towards the equator, and deserts towards the poles, reducing the overall savanna coverage. Once you’ve placed your savannas and tropical rainforests, separate the two with a thin band which will be your monsoon climates.

Now that we’ve placed our savannas on the map, let’s discuss how to make some flora and fauna. Within the savanna, all organisms need to have wildfire survival in mind. Those that don’t have a fire strategy won’t be sticking around for very long within the savanna. I’d like to hope that as an Australian, I know a thing or two about managing wildfire. The savanna flora on Locus, just like many of earth’s savanna flora, will have adapted to not only resist fire, but use it as a tool to assist with their own processes.

There are three main types of flora across savannas: grasses, shrubs, and trees. In fact, it is even possible for forests to exist within savannas, however savanna trees do not form a closed canopy, allowing light to easily reach the ground. As long as there is still an open canopy, forested areas still qualify as a savanna. Perhaps the most iconic savanna trees on earth are the acacia, baobab, and eucalyptus trees. As you can see, there is no distinct shape among the trees, and so long as you create trees that won’t form a closed canopy, you can go with whichever shape you’d like for your savanna trees.

Though there would be a number of different trees across the savannas of Locus, it is the Miraculum that are perhaps the most interesting. They are capable of a fictional process called severance, specifically thermo-severance. Here’s a link to the video for more information on how it works. Put simply though, severance consumes energy from its environment, with Miraculum’s thermo-severance specifically consuming thermal energy, reducing the temperature of the tree and the area nearby. This makes them excellent sources of reprieve from the heat for creatures of the savanna, which can often be seen in large packs hoarding around the trees. This is especially true during wildfires, where Miraculum provide small patches of safety for any creatures that can cram within the area. It is not uncommon for the otherwise charred barren landscapes after a wildfire to have conspicuously healthy Miraculum remaining, visibly unaffected by the fires, which has earned them their name.

Besides the trees of the savanna, it is perhaps grasses that are most important among the flora of their ecosystems. On earth, the three most common savanna grasses are bluestem, thatching grass, and kangaroo grass, with an honourable mention going out to elephant grass in wetter savannas. All of these grasses grow in dense tufts, are heavily drought resistant, grow reasonably well in temporarily waterlogged conditions, but are very frost intolerant. If we’re going to worldbuild grasses across our savannas, they’re probably going to have similar properties to these real-life grasses.

Let’s make our own savanna grass called Vell grass, which will be one of the most resilient folia across the planet. It grows especially well in moist conditions, though it has developed exceptional tolerance to droughts and water lodging, it supresses weeds, and grows quickly after grazing. As an Immortalis, it has what is called a “phoenix seed” below the surface, which is a highly resistant seed that is designed to grow only after the organism dies. Specifically, Vell Grass’ phoenix seed is exceptionally heat resistant. When bushfire occurs and passes over the Vell Grass, incinerating and destroying the above-ground organism, its phoenix seed germinates and regrows the plant. As far as grasses go, Vell grass is highly nutritious, and considering its hardiness and ability to quickly regrow after bushfire, Vell grass is a keystone species within the savannas of Locus, with almost all creatures reliant on Vell grass’ availability to thrive.

Now that we’ve looked at the flora of the savannas, let’s discuss some of the iconic creatures that inhabit the tropical plains. On earth, some iconic savanna herbivores are elephants, gazelles, meerkats, rhinos, warthogs, and zebras, while some iconic savanna carnivores are cheetahs, hyenas, and lions. Across the board we can see that creatures here are either fast or burrowing. Even the bulky rhinos can reach speeds above 50 kilometres per hour. These speeds help creatures to outrun wildfires, and selection here in the tropical plains is heavily weighted towards the fastest creatures surviving. As predators become faster, they outrun wildfires and catch prey easier, and so prey are also required to become faster or more evasive to survive. As prey becomes faster, they are more likely to survive wildfires, and so the cycle of natural selection continues. Similarly, burrowing creatures are more evasive and so require more perceptive predators to find them. What this means functionally is that predators across the savanna are likely to be exceptionally fast and have excellent senses, making them fantastic hunters, while prey are likely to be either fast or burrowing, and probably camouflage themselves in multiple ways to protect themselves from predators. 

Another common adaptation in savannas is migration, which occurs due to the wildly varying conditions between the wet and dry seasons. Animal migration refers to the long-distance movement of creatures to a different habitat. Migration is contrasted with dispersal, which refers to any time a creature or group of creatures move out of their habitat permanently. For the movement of creatures to be considered migration, it must be a regularly recurring activity, with animals moving back and forth predictably on a seasonal or annual basis. The exception to this is if movement occurs as part of an animal’s life cycle, such as Atlantic salmon leaving the river they were born in once they reach a certain size. Because it can be reasonably expected for all Atlantic salmon to do this, this process is still considered migration.

Across savannas, creatures migrate during the dry season in search of water. If droughts are localised, they may only move to a different area within their biome, but if droughts endure across the entire savanna, creatures may migrate to another biome entirely.

On Locus, the Saltus are herbivorous migratory creatures, with bodies not dissimilar to kangaroos, though with ornate horns like a stag. They have colouration that helps them to blend with grasses and dirt, and their large, powerful rear legs allow them to leap forward great distances, reaching speeds of up to 80 kilometres per hour for short sprints, and 40 kilometres per hour for sustained movement. There is significant sexual dimorphism within the species, with males growing far larger than females, and female horns also being far smaller than males. This dimorphism has come about as a result of the fierce competition between males, who lock horns with each other and then use their powerful legs to push their rivals around. Despite their large size and intra-species aggression, they are cowardly creatures whose first instinct is to run from an engagement. Their strategy for managing bushfire is also to flee, though their poor intelligence sometimes leads them to circle back into areas affected by fire. When not threatened by another species or by fire, they are exceptionally lazy and stagnant, which is a deliberate lifestyle adaptation to preserve energy to be used for escape.

The burrowing hypercarnivorous cousins of the Saltus are the Perilux, which has a similar bone structure but are visually quite different. They are much smaller than Saltus, and though still technically bipedal, stalk lower to the ground. Mechanically, they still hop around like Saltus do, though are more adapted to explosive movement over short distances, able to reach 100 kilometres per hour for 10-15 seconds but are unable to sustain anything higher than 8-10 kilometres per hour beyond that. Their spring-like rear legs allow them to reach top speed exceptionally quickly, and at their top speed they are the fastest creatures on the savanna. Uniquely, they slice their prey when they attack, causing it to bleed profusely. The Perilux will then disengage, stalking its prey’s blood trail as it slowly bleeds out. It has also adapted the capacity to change its skin colouration, not unlike a chameleon on earth, which assist it with camouflage while hunting. Colour changes are also used as means of social and sexual signalling. When encountering other Perilux, males flash yellow while females flash purple. From this initial interaction, a dazzling display of colourful communication will occur, with oranges and reds indicating sexual interest, blues indicating submission, and greens indicating hostility. These colour displays are intricately nuanced however, and Perilux can be observed having in-depth ‘visual conversations’ as they shift through colours, hues, and tones.

Next, we have the opportunistic tree dwelling Impes, which are heavily inspired by dropbears from Australian folklore. Though their diet consists mostly of leaves and fruits, they will drop from the trees they dwell in onto unsuspecting prey, attempting to land on their prey’s head where they viciously bite and scratch to incapacitate creatures they’ve ambushed, often successfully taking down creatures many times their size. It is in fact because of Impes that the savannas of Locus have no true apex predators, because even larger predators are still at risk of being pounced on by an Impes. They are nocturnal, and their grey fur helps with blending into their arboreal environment. Perhaps the most defining feature of the Impes however is their exceptionally poor intelligence, which translates into almost all areas of their lives. They are incapable of interpreting social signals between each other, and so have lost all courtship practices between males and females. Instead, Impes simply breed almost constantly, and it is not uncommon to find entire trees of Impes engaging in group sexual behaviour. They also have limited understanding of danger, which in part contributes to their willingness to prey on creatures many times their size. When bushfires occur, they simply stay put within the trees they are already in. Enough survive from being within Miraculum trees at the time of fires that this behaviour has not been forced to change. Nobody said that evolution had to be intelligent.

Finally, we have the Callidus, which if not for the Impes would be the apex predators of the savannas on Locus. Callidus are bipedal runners, and though females are slightly taller than males, their overall body mass is similar. They have developed coloured plumes of feathers that run down their necks, with females having feathers of monochromatic white, grey, or black, while males have brilliant arrays of different colours. They roam in packs called a ‘company’ with up to 20 members, usually with roughly equal numbers of males and females. These companies are highly social, with each member not only having a unique call, but a distinct vocalised sound that references that individual, which in communication is used like a name. Companies are polygamous, and it isn’t uncommon for all members of a company to have borne offspring with every opposite member of the group. Their intra-species socialisation doesn’t stop there though. If presented with the opportunity for larger prey, either in size or numbers, a company will work cooperatively with other companies, and in some cases multiple companies will work together, forming what is called a ‘battalion’. These battalions can include hundreds of Callidus, each communicating with each other to coordinate their predatory strategies. Callidus play important roles as a keystone species, keeping the numbers of other species in check, as well as being a critical resource for any scavengers across the savannas. They use their good sense of smell to detect wildfires early and are expert navigators to avoid affected areas. Callidus companies that come across each other will even communicate the direction of the fire and often cooperate as they evacuate. Unsurprisingly, Callidus are one of the most intelligent creatures across Locus, and a contender for one of the species that we’ll be looking at in the future that will go on to develop civilizations of their own.

So, to recap, savannas are categorised as areas that have a single wet season, with the rest of the year being dry and prone to bushfires. Flora and fauna must have adapted to this harsh environment in order to survive, establishing strategies to manage bushfire, drought, and predators. We looked at the iconic flora and fauna of savannas on earth, before creating some flora and fauna of our own.

Join me next time when we’ll cover worldbuilding deserts, yet another extreme environment. And until next time… stay awesome!