Were aurochsen numbers determined by food or predators?

I had an interesting e.exchange with a UK conservation researcher a while ago about whether the European aurochs population density was likely to have been top-down controlled by predators or bottom-up controlled by food supply. Or maybe a bit of both depending on the specifics of a given landscape, pack size of wolves etc?

We’ll never know for sure, of course. But we will soon have back-bred Tauros cattle that are intended to fill the ecological niche of the extinct aurochs, influencing the structure and function of landscapes in a similar way. So whether we think they were predator or food limited is important to conservation planning. If top-down regulation is key to the density (and grazing pressure) of aurochs, maybe we shouldn’t use Tauros unless and until we have wolves in the landscape, to ensure we don’t get over-abundance and compound the existing problem of deer over-abundance.

Another related question is: would predators, such as wolves, be sufficiently scary to create the ‘landscapes of fear’ effect, causing aurochs to be skittish, moving them on, and thus dissipating their grazing effects on landscapes?

The aurochs was a large grazing and herd-forming ungulate. Herd-forming is at least in part a predator-defence tactic. Herds of large ungulates such as bison and, presumably, aurochs, would more than likely confront a pack of wolves. They probably defended vulnerable calves by encircling them, heads out. A bull aurochs was a huge animal. They’d represent a formidable and potentially lethal target even for a pack of wolves. I’m not convinced wolves would be able to grab a calve among a herd of defensive aurochsen. Perhaps wolves would sit back, wait for the herd to move on, nudge them along through harassment at a distance, and target any older or ill individuals that are slow and fall behind the herd as it drifts off, targeting these once the main herd is at a safe distance. Could wolves achieve top-down control of aurochs under these circumstances?

And would wolves cause a herd of aurochs to flee? Bison tend to stand their ground. I’m not convinced that aurochs would stampede at the sight of a wolf pack. So would wolves create a landscape of fear for aurochsen as they clearly do with Cervids?

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