Today is a rare cloudless day for the rain-pseudoforests of east Loxodia. This is one of Apterra's largest tropical regions, home to a vast diversity of fauna. Peeking out from beneath a bush of Bouteloua is a small and nondescript form, a dedicated insectivore (a term here used loosely, as isopods are in reality non-insect crustaceans) that patrols the underbrush for woodlice and the occasional mosquito. Rattus leucocauda, as it is known scientifically, is in fact the smallest rodent species in this particular habitat, attaining a maximum size of only twenty grams. It scurries back into its burrow, hidden amongst the dense roots of the buffalograss.
The cause of its fear now makes itself apparent. A large, surly individual of Rattus gracilipes has just arrived on the scene. Luckily for the little shrew-like critter, the bigger rodent ate its fill of kiwi carrion earlier this morning. As it pushes aside some palm-grass stems, droplets of dew roll off the blades and onto its body. The three-kilogram beast shakes itself dry, flinging the water off its shaggy grey fur in all directions. It flicks a mosquito with its tail, sending the parasite flying off in search of an easier target, then munches on a stalk of large rat-grass grains, pulverizing them with the same powerful premolars it used earlier to grind up its breakfast. It slinks off, heading back to its den to nap and digest its food.
The snap of a twig alerts its neighbors to its return. These herbivores, belonging to the species Rattus rubrops, are unaware that the fearsome predator is done hunting for the day. Huddling in their nest beneath a rock, they tend to their young, which are raised communally both sexes. The male is the species's namesake, as it has bright red patches of fur on its face, hands, and calves. Once the rats realize they're in no danger, those who aren't tasked with feeding the pups cautiously return to their foraging. They patrol together, seeking out patches of edible grass in their territory. They take care not to completely exhaust their food source, as their young cannot walk, so the family must live in this area for at least a few more weeks. Their neighbors, though, are not so keen to leave a blade of grass uneaten.
A small herd of Rattus migratorius is passing through. These tall, lanky grazers have young of their own, but unlike those of their cousins, these pups are mobile. This species is born precocial, needing no more than a day before it can follow its parents and join the herd. This grants them the ability to stay on the move; while other herbivorous rats must take care not to overgraze within their home range, this species does not form long-term territories and therefore can afford to eat as much as it pleases. In exchange for the large population sizes made possible by this way of life, it cannot return to any single area more than once or twice a year. Therefore, while its short-term presence is a threat to the less-mobile grazers it comes across, the latter will get a chance to recover during the following months.
This balance, however, is a precarious one. While the two grazing rats currently maintain a state of niche partitioning, the hyper-migratory lifestyle of R. migratorius is destined to lead it to bigger and better things, at the expense of many of its relatives. R. rubrops in particular is one of the lucky ones; it is still adaptable enough to switch to different food sources when the time comes it can no longer compete with its cousins. For now, though, R. rubrops adults scour their land for any remaining scraps, returning home with the meager pickings they manage to find. This litter of pups may never live to adulthood, but their ecosystem is coming to life more than ever as the Age of Rats marches on.