Just as prairie dogs facilitate the prairie bison by enriching patches of lawn, perhaps beavers facilitated the wood bison by creating riparian meadows of sweet sedges.
Prof. Mumblebard claims: “Because rodents are generally smaller than hoofed mammals, it’s unexpected for rodents to facilitate grazing ungulates. The only possible exception is prairie dogs, which appear to create food for the American bison rather than competing with it. If this qualifies as facilitation, it occurred in a limited area only. Although beavers are perhaps the most powerful of rodents, they had little to do with bisons because the former resided in forested valleys whereas the latter migrated on treeless plains.”
Robin and the Honey Badger respond: “The American bison is indeed at home in the open but its distribution extends across the boreal forests through western Canada to Alaska. As a result, this bison would probably have visited beaver meadows repeatedly along its original migratory routes. Beaver meadows offer herbaceous plants more nutritious than those in the surrounding forests. And sedges, which are common in beaver meadows, are a preferred food of the American bison. The facilitation of bisons by beavers may therefore be greater than realised. The European bison, if truly a forest-adapted species, was particularly likely to have benefited from riverside meadows created by the European beaver, particularly in winter. This helps to explain why the remaining populations of European bison have needed supplementary feeding where beavers have been exterminated. Other herbivores foraging in beaver meadows and ponds on both the northern continents include wapiti, red deer and moose/elk. An image search for tourists viewing bisons and other herbivores in forested landscapes: which species is most frequently spotted in beaver meadows?”
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How beavers engineered landscapes for bison