Intelligent and adaptable, the Common Raven, Corvus corax, is one of the most widely distributed passerine birds ranging across much of the Holarctic where it largely exists as an opportunistic scavenger. Much of its success and recent spread in distribution can be linked to recent declines in persecution as well as activities like agriculture which may unintentionally subsidise them. Agriculture is the most widespread type of land management and one of the greatest drivers of environmental change and loss of biodiversity, often reducing species’ ability to provide important ecosystem services. Large areas of land in the UK are managed for agriculture, in particular Wales, where notable changes in livestock have occurred since the 1950s. In addition, northwest Wales supports some of the highest population densities of Raven in Britain, and so offers an excellent study area. Here, the relationship between Raven breeding performance and livestock practices on Anglesey and the Carneddau from 2003 to 2018 have been investigated.
On Anglesey, raven breeding performance was negatively related to dairy cattle density and percentage of area farmed. This has likely arisen due to changes in stocking densities of dairy cattle that have occurred in an intensively managed landscape, which may have impacted food availability for breeding Raven pairs. Simultaneously, Raven breeding performance on Anglesey was positively related to area of permanent pasture and area of rough grazing. The former may benefit breeding Ravens by providing less competition from specialist species. On the other hand, areas of rough grazing can support more biodiversity and are commonly associated with sheep, both of which may increase foraging opportunities.
In the Carneddau, the breeding performance of Ravens had no relationship to livestock practices. This is likely explained by the topography and poor agricultural productivity of the region which limits the presence of high intensity livestock practices. This study provides evidence that the breeding performance of Ravens in northwest Wales is more likely to be influenced by changing livestock practices in intensive agricultural landscapes than in extensive agricultural landscapes. While this could have important implications for conserving and managing similar avian scavengers in agricultural landscapes, further research is necessary to better understand the relationships presented here.