Green alder shrubs (Alnus viridis) increasingly overgrow mountain pastures and impair ecosystem services by loss of biodiversity, eutrophication and greenhouse gas emissions. Over the centuries, grazing livestock, especially goats, preserved these ecosystems by impeding shrub expansion. Nowadays, livestock numbers are decreasing on remote mountain pastures and goat farming has become unprofitable. A grazing experiment tested if robust cattle and sheep can replace goats as antagonists of green alder and if the available fodder is sufficient. GPS tracking and vegetation mapping were used to analyse movement behaviour and debarking activity of Dexter cattle, Engadine sheep and Pfauen goats. The forage quality of green alder and its understorey was unexpectedly high. Cattle used the space least evenly, preferred flat slopes and open pastures, spent least amount of time in green alder and did not debark any green alder branches. Engadine sheep visited the shrubs nearly as often as goats, but preferred flat slopes and short vegetation. Unexpectedly, this sheep breed debarked a significantly higher share of green alder branches than goats. Dexter cattle cannot replace goats for fast green alder clearance but they may impede shrub encroachment in the long term. Engadine sheep are well suited to recreate biodiverse semi-natural open pastures and maintain their ecosystem services.