Farmland bird populations have strongly declined across Europe over the last decades due to agriculture intensification, despite successive reforms of EU's Common Agricultural Policy (CAP). In parallel, CAP has led to a reduction of fallow land, a critical habitat for biodiversity in agroecosystems. Fallow land in Spain, a country harboring the largest European populations of many endangered farmland birds, has decreased by 1.1 million ha in 15 years. The significant positive relationship between yearly change rates of the Spanish Farmland and Cereal Bird Indices (FBI and CBI) and fallow surface change highlights the adequacy of fallow land cover as an indicator of the state of farmland bird communities at country level. Moreover, the strong and positive association between the reduction in abundance of the fallow specialist little bustard and fallow surface suggests a potential causal link between these two factors. These results highlight the need for a new CAP that guarantees the maintenance of fallow land in European agroecosystems if farmland bird populations are to be conserved.
Interspecific competition is a dominant force in animal communities that induces niche shifts in ecological and evolutionary time. If competition occurs, niche expansion can be expected when the competitor disappears because resources previously inaccessible due to competitive constraints can then be exploited (i.e., ecological release). Here, we aimed to determine the potential effects of interspecific competition between the little bustard (Tetrax tetrax ) and the great bustard (Otis tarda ) using a multidimensional niche approach with habitat distribution data. We explored whether the degree of niche overlap between the species was a density‐dependent function of interspecific competition. We then looked for evidences of ecological release by comparing measures of niche breadth and position of the little bustard between allopatric and sympatric situations. Furthermore, we evaluated whether niche shifts could depend not only on the presence of great bustard but also on the density of little and great bustards. The habitat niches of these bustard species partially overlapped when co‐occurring, but we found no relationship between degree of overlap and great bustard density. In the presence of the competitor, little bustard's niche was displaced toward increased use of the species' primary habitat. Little bustard's niche breadth decreased proportionally with great bustard density in sympatric sites, in consistence with theory. Overall, our results suggest that density‐dependent variation in little bustard's niche is the outcome of interspecific competition with the great bustard. The use of computational tools like kernel density estimators to obtain multidimensional niches should bring novel insights on how species' ecological niches behave under the effects of interspecific competition in ecological communities. ; Belianes and Bellmunt fieldwork was financed by REGSEGA (Regs Sistema Segarra‐Garrigues), Departament de Medi Ambient i Habitatge (Generalitat de Catalunya). Funding was also provided by the Spanish Ministry of Science (CGL2009‐13029/BOS); the REMEDINAL2 and REMEDINAL3 networks of the CAM (S‐2009/AMB/1783 and S2013/MAE‐2719). R.T. was supported by a PhD grant from the Spanish Minister of Education (FPU grant no. AP2009‐0762) and a postdoctoral fellowship funded by REMEDINAL3 (S2013/MAE‐2719). FC was supported by the Andalucía Talent Hub Program launched by the Andalusian Knowledge Agency, cofounded by the European Union's Seventh Framework Program, Marie Skłodowska‐Curie actions (COFUND–Grant Agreement n° 291780) and the Ministry of Economy, Innovation, Science and Employment of the Junta de Andalucía.
Interspecific competition is a dominant force in animal communities that induces niche shifts in ecological and evolutionary time. If competition occurs, niche expansion can be expected when the competitor disappears because resources previously inaccessible due to competitive constraints can then be exploited (i.e., ecological release). Here, we aimed to determine the potential effects of interspecific competition between the little bustard (Tetrax tetrax) and the great bustard (Otis tarda) using a multidimensional niche approach with habitat distribution data. We explored whether the degree of niche overlap between the species was a density-dependent function of interspecific competition. We then looked for evidences of ecological release by comparing measures of niche breadth and position of the little bustard between allopatric and sympatric situations. Furthermore, we evaluated whether niche shifts could depend not only on the presence of great bustard but also on the density of little and great bustards. The habitat niches of these bustard species partially overlapped when co-occurring, but we found no relationship between degree of overlap and great bustard density. In the presence of the competitor, little bustard's niche was displaced toward increased use of the species' primary habitat. Little bustard's niche breadth decreased proportionally with great bustard density in sympatric sites, in consistence with theory. Overall, our results suggest that density-dependent variation in little bustard's niche is the outcome of interspecific competition with the great bustard. The use of computational tools like kernel density estimators to obtain multidimensional niches should bring novel insights on how species' ecological niches behave under the effects of interspecific competition in ecological communities. ; Seventh Framework Programme, Grant/Award Number: 291780; Ministerio de Ciencia e Innovación, Grant/Award Number: CGL2009-13029/BOS; Ministerio de Educación, Cultura y Deporte, Grant/Award Number: AP2009-0762; REGSEGA; Departament de Medi Ambient i Habitatge; REMEDINAL2, Grant/Award Number: S-2009/AMB/1783; REMEDINAL3, Grant/Award Number: S2013/MAE-2719; Andalusian Knowledge Agency; European Union's Seventh Framework Program Marie Skłodowska-Curie actions (COFUND–Grant Agreement n° 291780); Ministry of Economy, Innovation, Science and Employment of the Junta de Andalucía. ; Peer Reviewed
Stress in birds has been widely studied through the measurement of heterophil-to-lymphocyte ratio (H/L ratio). In this study we aimed to assess for the first time the potential variation of stress, measured as H/L ratio, associated to geography (between-country variation) and seasonality (between seasons and within the breeding season), as well as the leukocyte profiles, in the threatened Dupont's Lark (Chersophilus duponti), using samples from Spain and Morocco. Furthermore, we tested whether variation in H/L ratio was associated with variables such as population density, presence of blood parasites and individual body condition. We found that H/L ratio did not vary between countries, but individuals captured during the breeding season showed higher values of H/L compared to non-breeding ones. Neither male density, nor date within the breeding season had an effect on the H/L ratio. In Spain, individuals with higher body condition showed lower H/L ratio regardless of whether they were malaria-infected. In Morocco, malaria-infected individuals showed higher values of H/L ratio than the non-infected birds. Moreover, we found that our average values of H/L ratio in Morocco were within the ranges of other passerines, but not in Spain. Individuals with higher H/L ratios may be more stressed or present higher capability to face stressful situations. Although H/L ratio is a useful and relatively easy way to obtain measure of stress, the impact that the environment might have on stress and the way it is explained by H/L ratio must be addressed carefully. This study provides new insight for this species' biology and provides useful reference information to test the status and survival of other populations. ; This study was partially funded by the authors, the Spanish Ministry of Environment (MMA; J.J. Areces and B. Heredia), the Spanish Agency for International Cooperation (AECI), and the LIFE Ricoti (LIFE15-NAT-ES-000802), supported by the European Comisison. D.B.R. was supported by FPI-UAM fellowship from the Universidad Autónoma de Madrid (UAM), and the collaboration of the Instituto de Investigación en Recursos Cinegéticos (IREC-CSIC-UCLM). We wish to thank the Servicio de Vida Silvestre of Conselleria D'infraestructures, Territori i Medi Ambient (Generalitat Valenciana) and the Moroccan government for ringing permits and supporting our work. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.
[EN] The next reform ofthe EU Common Agricultural Policy (CAP) for the period 2021-2027 (currently extended to 2023-2030) requires the approval by the European Commission of a Strategic Plan with environmental objectives for each Member State. Here we use the best available scientific evidence on the relationships between agricultural practices and biodiversity to delineate specific recommendations for the development of the Spanish Strategic Plan. Scientific evidence shows that Spain should (1) identify clear regional biodiversity targets and the landscape-level measures needed to achieve them; (2) define ambitious and complementary criteria across the three environmental instruments (enhanced conditionality, eco-schemes, and agri-environmental and climate measures) of the CAP's Green Architecture, especially in simple and complex landscapes; (3) ensure that other CAP instruments (areas of nature constraints, organic farming and protection of endangered livestock breeds and crop varieties) really support biodiversity; (4) improve farmers' knowledge and adjust measures to real world constraints; and (5) invest in biodiversity and ecosystem service monitoring in order to evaluate how the Plan achieves regional and national targets andto improve measures if targets are not met. We conclude that direct assessments of environmental objectives are technically and economi- cally feasible, can be attractive to farmers, and are socially fair and of great interest for improving the environmental effectiveness of CAP measures. The explicit and rigorous association of assessments and monitoring, relating specific environmental indicators to regional objectives, should be the main criterion for the approval of the Strategic Plan in an environmentally-focused CAP2023-2030. ; [ES] La reforma de la Política Agraria Común (PAC) para el periodo 2021-2027 (extendido en la actualidad a 2023-2030) exige que la Comisión Europea apruebe un Plan Estratégico por cada Estado Miembro con claros objetivos ambientales. En este trabajo desarrollamos recomendaciones específicas para la elaboración del Plan Estratégico para los sistemas agrícolas españoles, basadas en la mejor evidencia científica disponible sobre las relaciones entre la gestión agrícola y los componentes de la biodiversidad. La evidencia científica muestra que España debe 1) identificar objetivos regionales claros relativos a la biodiversidad de los medios agrarios y las medidas a nivel paisajístico necesarias para alcanzarlas; 2) definir criterios ambiciosos y complementarios para los tres instrumentos ambientales (condicionalidad extendida, eco-esquemas y medidas agroambientales y climáticas) de la Arquitectura Verde de la PAC, especialmente en paisajes sencillos y complejos; 3) garantizar que otros instrumentos de la PAC (zonas desfavorecidas, agricultura ecológica y protección de razas ganaderas y variedades de cultivos en peligro de extinción) favorecen realmente la diversidad biológica; 4) mejorar el conocimiento de los agricultores y ajustar las medidas a las limitaciones del mundo real; y 5) invertir en seguimiento de la biodiversidad y sus servicios ecosistémicos asociados con el fin de evaluar si el Plan alcanza los objetivos regionales y nacionales y mejorarlos adaptativamente si no lo consigue. Concluimos que la evaluación directa de los objetivos ambientales es técnica y económicamente viable, puede ser atractiva para los agricultores, es socialmente justa y de gran utilidad en la mejora de la efectividad de las medidas de la PAC. Una combinación rigurosa de seguimiento y evaluación de medidas y objetivos adaptados regionalmente mediante indicadores ambientales directos y claros debería ser el criterio que guíe la aprobación del Plan Estratégico para una PAC 2023-2030 centrada en el medio ambiente y orientada a la conservación de la biodiversidad. ; Peer reviewed
