Low intensity, mixed livestock grazing improves the breeding abundance of a common insectivorous passerine.
Livestock grazing is a major driver of ecosystem change and has been associated with significant declines in various bird species in Britain and worldwide. However, there is little experimental evidence to show how grazing affects bird populations. We manipulated livestock densities in a replicated field experiment and found that mixed sheep and cattle grazing, at low intensity, improved the breeding abundance of a common upland passerine, the meadow pipit Anthus pratensis, after two years. Plots stocked with sheep alone (at high or low density) or not stocked at all held fewer pipit territories. Despite a year-on-year decline in pairs of meadow pipits in intensively grazed plots, we found no effect of sheep number on breeding abundance. Our results support the hypothesis that mixed species of herbivores generate greater heterogeneity in vegetation structure, which modifies prey availability, resulting in a greater abundance of birds. The results of our study should inform the management of grassland areas and enhance the abundance of some bird species, particularly in areas that have seen significant shifts from mixed livestock grazing to grazing dominated by single species of animals.
Evans
Darren M
DM
NERC Centre for Ecology & Hydrology, Hill of Brathens, Banchory, Aberdeenshire AB31 4BW, UK. darren.evans@bristol.ac.uk
Redpath
Stephen M
SM
Evans
Sharon A
SA
Elston
David A
DA
Gardner
Charles J
CJ
Dennis
Peter
P
Pakeman
Robin J
RJ
D000822:Animal Husbandry / Q000379:methods*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle; D017753:Ecosystem; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D016014:Linear Models; D046109:Passeriformes / Q000502:physiology*; D011156:Population Density; D011897:Random Allocation; D012098:Reproduction / Q000502:physiology*; D012756:Sheep; D013997:Time Factors