In this experiment, the density of understorey birds at a series of sites in two areas either side of a stockproof fence were compared. Once side had limited grazing (mainly from native herbivores), and the other was heavily grazed by feral herbivores, mostly horses. Bird counts were done at the sites either side of the fence (the Before measurements). Then the herbivores were removed, and bird counts done again (the After measurements). The measurements are the total number of understorey-foraging birds observed in three 20-minute surveys of two hectare quadrats.
grazing