Species living in high mountain areas are currently threatened by climate change and human land use changes. High‐elevation birds frequently inhabit island‐like suitable patches around mountain peaks, and in such conditions the capability to exchange individuals among patches is crucial to maintain gene flow. However, we lack information regarding the dispersal ability of most of these species and the possible influence of landscape features on dispersal. In this study, we used population genomics and landscape resistance modelling to investigate dispersal in a high‐elevation specialist migratory bird, the water pipit Anthus spinoletta. We aimed to assess the levels of gene flow in this species within a wide area of the European Alps, and to assess the effects of environmental characteristics on gene flow, by testing the isolation by distance (IBD) hypothesis against the isolation by resistance (IBR) hypothesis. We found clear support for IBR, indicating that water pipits preferentially disperse across suitable breeding habitat (i.e., high‐elevation grassland). IBR was stronger in the part of the study area with less extended suitable habitat. Landscape resistance was slightly better described by habitat suitability models than landscape connectivity models. Despite the observed IBR, gene flow within the study area was high, probably also because of the still wide and relatively continuous breeding range. The forecasted reduction of range of this species may lead to stronger effects of IBR on gene flow. Other high‐elevation specialist birds may show similar IBR patterns, but with possibly stronger effects on gene flow because of their more reduced and patchy habitats.

Summary Farmland biodiversity is declining worldwide, and especially in Western countries largely owing to the large-scale intensification of agricultural practices. The Little Bustard Tetrax tetrax is a steppe bird adapted to agro-pastoral ecosystems in Western Europe, and is one of those many farmland species declining due to changes in agricultural production systems. In the EU, the majority of the extant population of this species is concentrated in the Iberian Peninsula. In Italy, the species has now disappeared from the mainland and is currently present only in Sardinia, where two populations, in the central-western areas, hold about two-thirds of the whole island’s numbers, with the rest scattered across numerous smaller nuclei. While there are indications and anecdotal information suggesting a possible population decline during recent decades, robust monitoring across different time periods that would allow a comparison of numbers is lacking in Sardinia. Here we repeated a Little Bustard survey performed in 2008 in two areas of western Sardinia: Abbasanta, which is one of the two strongholds for the species in Sardinia, and Campeda, which holds a small population (about 10 territorial males). Using the same methodology as in the past survey, we assessed current population size and density, and quantified changes over time. We found alarming declines, at a rate of around 30% in 14 years in both areas, with an estimated current population of 87 males in Abbasanta and 8 males in Campeda. We highlight current and emerging threats, such as the downsizing of the Special Protection Area of Abbasanta, and the encroachment of solar power plants within the same area.

The morphology of bird wings is subject to a variety of selective pressures, including migration, predation, habitat structure and sexual selection. Variation in wing morphology also occurs at the intraspecific and intrapopulation level, and can be related to sex, age, migration strategy and environmental factors. The relationship between environment and intraspecific variation in wing morphology is still poorly understood. In this work, we studied the relationship between wing morphology and breeding environment in a high‐elevation specialist bird, the water pipit Anthus spinoletta. We calculated wing isometric size, pointedness and convexity of 84 birds mist‐netted at breeding sites in year 2021 in the European Alps. We then searched for associations between these traits and potentially relevant breeding site characteristics (vegetation structure, elevation, latitude). For all wing traits, sex and one or more environmental factors best explained the variation, with environmental factors explaining between 3 and 8% of the variation. Wing size was negatively related to tree cover and wing convexity was negatively related to bush cover. Elevation contributed to explain variation in wing pointedness, but the direction of its effect was unclear. The negative relationship between wing size and tree cover could be due to intraspecific competition, i.e. to the relegation of smaller winged low‐quality individuals in marginal grassland areas. Higher wing convexity could improve predator escape ability in areas with scarce protecting vegetation, with possible effects on habitat choice. These findings represent one of the few demonstrated cases of wing morphology–environment relationships at the intraspecific level.