Crawling after the trampling
The snowy trenchcrawler

The bad temperament of tramplerats make them unapproachable by any large mammal, not even herbivores, which are often seen grazing together but maintaining at least a 30-meter distance (100 feet). Only one large species is tolerated by this rodent, due to their parallel evolution in the past: the snowy trenchcrawler (Briorostris cuniculus). This cassowary-sized bird is a rostrid directly evolved from the polar trenchcrawler and, unlike its ancestors and other small contemporary relatives, it does not live in burrows but roams across the vast grassy expanse of the trample steppe. Short and wide burrows are only constructed during the breeding season, in order to protect hatchlings from cold winds and predators.
They are highly social birds that move in familiar groups of up to 20 individuals, often grazing within tramplerat herds. The two species coexist thanks to a symbiotic relationship: while trenchcrawlers have much better vision than tramplerats and can easily spot any predators in the steppe, the tramplerat is stronger and acts as a better defense against these dangers.

Despite their small size compared to other rostrids and rodents of the trample steppe, trenchcrawlers are fundamental to the maintenance of this biome. They are often classified as "pioneer grazers" because of their unspecialized diet, including a good percentage of mosses and lichens, which can reduce the overall productivity of the biome. By reducing the biomass of mosses and lichens, trenchcrawlers can help convert depleted areas into more productive ones, preparing the way for more specialized grazers like stottmice, tramplerats, and other rostrids.

Despite their long legs, trenchcrawlers are not fast runners and prefer standing their ground against any threat. Their beak, capable of exerting a force of up to 4000 Newtons (900 lbs), is a formidable weapon that can easily deter even fierce geotters, like beasters. Only stealthy predators, like barkdowners, are capable of ordinarily hunting this bird by approaching them from the back, the blind spot of any rostrid*, and then clinging to their neck in order to damage the carotid.

Thanks to their adaptable diet, trenchcrawlers can be found even in much harsher environments than the trample steppe, such as the steep rocky habitats of the Antarctandes, but also the tundra environments of the Drop Islands. Here, a significant population of 400,000 trenchcrawlers has adapted to feed on the few palatable plants found in these barren islands. The population is fragmented during the summer on the various islands of the archipelago, but it often reunites during winter when the sea ice reconnects these islands, and the migration movements of trenchcrawlers become more significant.

*the ancestor of all Biancocenic rostrids, the woodclimber, possessed a binocular vision, an adaptation which was maintained relatively untouched in its descendants.