Can current farmland landscapes feed declining steppe birds? Evaluating arthropod abundance for the endangered little bustard (Tetrax tetrax) in cereal farmland during the chick-rearing period: Variations between habitats and localities

Agriculture intensification threatens farmland bird populations because, among other reasons, it reduces the availability of food resources required to rear their offspring. In our study, we sampled and analyzed total arthropod abundance, biomass and richness, and orthopteran and coleopteran abundance and biomass in different agricultural habitats (alfalfa fields, stubble fields, grazed fields, and field margins) across 4 study localities with different levels of agriculture abandonment–intensification, comparing between areas used and not used by one of the most threatened farmland birds in Europe, the little bustard (Tetrax tetrax), during the chick-rearing season. Field margins were the taxonomically richest habitat, while alfalfa fields presented significantly higher total arthropod abundance and biomass than other habitats. All arthropod variables were the highest in the localities with clear conservation-focused agrarian management, and the lowest in the most intensive one. Areas used by little bustards had higher orthopteran and coleopteran abundance and biomass than nonused areas, except for coleopteran biomass in grazed fields. These results highlight the relevance of these arthropods for the species, the importance of dry alfalfa fields as food reservoirs in this critical time of year, the food scarcity in sites where agrarian management disregards farmland bird conservation, and the role of stubbles as providers of food resources during the chick-rearing season in areas used by the species. The adequate management of alfalfa fields and stubbles to provide those key resources seems crucial to improve little bustard breeding success.We thank the International Fund for Houbara Conservation (IFHC) and Fundación Patrimonio Natural (FPN) de Castilla y León in the persons of Cédric Ferlat (IFHC), David Cubero (Dirección General de Medio Natural, Junta de CyL), and Francisco Jiménez (FPN) for their financial, administrative, and logistic support. This paper also contributes to project S2018/EMT-4338 REMEDINAL TE-CM from Comunidad de Madrid. We are also thankful to the officers responsible for the Reserve of Villafáfila, Mariano Rodíguez y Jesús Palacios. Little bustard spring survey data were kindly provided by SEO-BirdLife.Peer reviewe

Effects of habitat and land use on breeding season density of male Asian Houbara Chlamydotis macqueenii

Landscape-scale habitat and land-use influences on Asian Houbara Chlamydotis macqueenii (IUCN Vulnerable) remain unstudied, while estimating numbers of this cryptic, low-density, over-hunted species is challenging. In spring 2013, male houbara were recorded at 231 point counts, conducted twice, across a gradient of sheep density and shrub assemblages within 14,300 km² of the Kyzylkum Desert, Uzbekistan. Four sets of models related male abundance to: (1) vegetation structure (shrub height and substrate); (2) shrub assemblage; (3) shrub species composition (multidimensional scaling); (4) remote-sensed derived land-cover (GLOBCOVER, 4 variables). Each set also incorporated measures of landscape rugosity and sheep density. For each set, multi-model inference was applied to generalised linear mixed models of visit-specific counts that included important detectability covariates and point ID as a random effect. Vegetation structure received strongest support, followed by shrub species composition and shrub assemblage, with weakest support for the GLOBCOVER model set. Male houbara numbers were greater with lower mean shrub height, more gravel and flatter surfaces, but were unaffected by sheep density. Male density (mean 0.14 km-2, 95% CI, 0.12‒0.15) estimated by distance analysis differed substantially among shrub assemblages, being highest in vegetation dominated by Salsola rigida (0.22 [CI, 0.20‒0.25]), high in areas of S. arbuscula and Astragalus (0.14 [CI, 0.13‒0.16] and 0.15 [CI, 0.14‒0.17] respectively), lower (0.09 [CI, 0.08‒0.10]) in Artemisia and lowest (0.04 [CI, 0.04‒0.05]) in Calligonum. The study area was estimated to hold 1,824 males (CI: 1,645‒2,030). The spatial distribution of relative male houbara abundance, predicted from vegetation structure models, had the strongest correspondence with observed numbers in both model-calibration and the subsequent year’s data. We found no effect of pastoralism on male distribution but potential effects on nesting females are unknown. Density differences among shrub communities suggest extrapolation to estimate country- or range-wide population size must take account of vegetation composition

Migratory Pathways and Connectivity in Asian Houbara Bustards: Evidence from 15 Years of Satellite Tracking

Information on migratory pathways and connectivity is essential to understanding population dynamics and structure of migrant species. Our manuscript uses a unique dataset, the fruit of 103 individual Asian houbara bustards captured on their breeding grounds in Central Asia over 15 years and equipped with satellite transmitters, to provide a better understanding of migratory pathways and connectivity; such information is critical to the implementation of biologically sound conservation measures in migrant species. At the scale of the distribution range we find substantial migratory connectivity, with a clear separation of migration pathways and wintering areas between western and eastern migrants. Within eastern migrants, we also describe a pattern of segregation on the wintering grounds. But at the local level connectivity is weak: birds breeding within the limits of our study areas were often found several hundreds of kilometres apart during winter. Although houbara wintering in Arabia are known to originate from Central Asia, out of all the birds captured and tracked here not one wintered on the Arabian Peninsula. This is very likely the result of decades of unregulated off-take and severe habitat degradation in this area. At a time when conservation measures are being implemented to safeguard the long-term future of this species, this study provides critical data on the spatial structuring of populations

European Red List of Habitats Part 1. Marine habitats

The European Red List of Habitats provides an overview of the risk of collapse (degree of endangerment) of marine, terrestrial and freshwater habitats in the European Union (EU28) and adjacent regions (EU28+), based on a consistent set of categories and criteria, and detailed data and expert knowledge from involved countries1. A total of 257 benthic marine habitat types were assessed. In total, 19% (EU28) and 18% (EU28+) of the evaluated habitats were assessed as threatened in categories Critically Endangered, Endangered and Vulnerable. An additional 12% were Near Threatened in the EU28 and 11% in the EU28+. These figures are approximately doubled if Data Deficient habitats are excluded. The percentage of threatened habitat types differs across the regional seas. The highest proportion of threatened habitats in the EU28 was found in the Mediterranean Sea (32%), followed by the North-East Atlantic (23%), the Black Sea (13%) and then the Baltic Sea (8%). There was a similar pattern in the EU28+. The most frequently cited pressures and threats were similar across the four regional seas: pollution (eutrophication), biological resource use other than agriculture or forestry (mainly fishing but also aquaculture), natural system modifications (e.g. dredging and sea defence works), urbanisation and climate change. Even for habitats where the assessment outcome was Data Deficient, the Red List assessment process has resulted in the compilation of a substantial body of useful information to support the conservation of marine habitats