Extensive sheep grazing is associated with trends in steppe birds in Spain: recommendations for the Common Agricultural Policy

Abstract

Iberian natural steppes have traditionally been used for extensive sheep grazing, which has been noted to be positively associated with steppe bird abundance and diversity. Sheep numbers in Spain, which harbors the largest European populations of many steppe bird species, decreased by 9.2 million (37.3%) between 1992 and 2020. Steppe birds in Spain have faced dramatic declines during the same period, but there is a lack of knowledge about the potential association between sheep and open-habitat bird declines. We used sheep data from the Spanish Ministry of Agriculture and bird data (1998–2018) from the Spanish Common Bird Monitoring Program to assess the association at the Spanish scale between sheep decline and the Farmland Bird Index (FBI) and the Natural Shrub-steppe Bird Index (SBI). We also used an independent dataset on population trends of the Dupont’s Lark (Chersophilus duponti) to assess the relationship between sheep numbers and the decline of this threatened steppe specialist passerine in Spain, whose European population is restricted to Iberian natural steppes. To test for a spurious relationship between temporal series, variables were tested for cointegration. After confirming cointegration, we found a strong positive relationship between sheep abundance and the trends of the FBI and SBI indices during the period 1998–2018. The association between sheep abundance and trends of the Dupont’s Lark (2004–2015) was positive although it was not statistically significant. Although the main causes of decline of farmland and steppe birds are mainly related to agricultural intensification and land use changes, the correlation found, using two independent cointegrated datasets, between the reduction in farmland and shrub-steppe birds and sheep numbers at the country scale suggests that the decline of steppe birds in Spain may be also associated with the decline in sheep numbers. This agrees with previous studies that found a positive relationship between intermediate levels of sheep grazing and steppe bird abundance in Iberian steppes. Further research (e.g. experimental studies) is needed to corroborate our study and identify the most appropriate level of grazing intensity for protecting the most farmland and shrub-steppe birds. Our results suggest that the promotion of extensive grazing should be considered as a key factor in future Common Agricultural Policy reforms and conservation programmes to protect steppe birds.

Dietary niche overlap and resource partitioning among six steppe passerines of Central Spain using DNA metabarcoding

“…1988). Since the middle of the last century, Iberian shrub‐steppes have been undergoing rapid anthropogenic changes, mainly due to agricultural intensification, land‐use changes (afforestation, infrastructure development), and the abandonment of traditional sheep grazing (Laiolo & Tella 2006, Traba & Morales 2019, Traba & Pérez‐Granados 2022), leading to the reduction and fragmentation of these habitats and, hence, to an increase in the decline of shrub‐steppe bird populations (Santos & Suárez 2005, Laiolo & Tella 2006, Traba & Morales 2019). Some steppe bird species, such as the endangered Dupont's Lark Chersophilus duponti , the Greater Short‐toed Lark Calandrella brachydactyla , Thekla's Lark Galerida theklae and the Western Black‐eared Wheatear Oenanthe hispanica , among others, present their main European populations in the Iberian shrub‐steppes (Santos & Suárez 2005), which makes these landscapes of great conservation value in the European context.…”

Landscape features influencing gene flow and connectivity of an endangered passerine

“…In all, it is imperative to guide management efforts to conserve and restore steppe landscape features, characterized by scattered and mosaic‐structured vegetation with predominance of low sclerophyllous shrublands, which provide both suitable breeding grounds and stepping‐stones for this endangered bird and related steppe species. For instance, by limiting the expansion of intensive crops or afforestation, or recovering extensive livestock grazing, whose decline has a direct impact on steppe habitat because it favours forest recovery following secondary vegetation succession (Martínez‐Valderrama et al., 2021 ; Reverter et al., 2019 ; Traba & Pérez Granados, 2022 ).…”

Range Contraction and Population Decline of the European Dupont’s Lark Population

“…Habitat loss and habitat transformation, owing to human activity, such as ploughing steppe habitats, wind farm development within and around occupied sites and afforestation are among the main drivers behind the declining status of the species [13,16,18]. However, the steep decline in extensive grazing, mainly by sheep [17], seems also to have strong consequences by decreasing the habitat quality [42]. Thus, increasing both the habitat quantity (through restoration measures) and quality (by the promotion of extensive grazing and tree/shrub clearance) is critical for the species conservation.…”

“…In the case of open habitats such as grasslands and steppes, habitat fragmentation and land use changes are the main drivers of habitat loss and degradation [13][14][15][16]. In the Iberian steppes, specifically, agricultural intensification and the abandonment of extensive grazing have been documented as the main threats to these rare and valuable habitats, and to steppe-specialist species [17]. The Dupont's lark (Chersophilus duponti) is a steppe bird of particular concern, being among the most threatened European birds [18] and included within the 65 priority bird species inhabiting steppes [19].…”