Understanding diversity patterns along environmental gradients lies at the heart of community ecology and conservation. Previous studies have found variation in bird diversity and density along “natural” elevational gradients in the Tropical Andes Hotspot. However, there is still a lack of knowledge about how bird communities respond to traditional land-use patterns, in association with other multiple drivers, along elevations. In the present study, we investigated biotic, abiotic and anthropogenic sources of variation associated with bird species diversity, density and turnover along a 3000-m elevational gradient, in southern limit of the Tropical Andes Hotspot, northern Chile. Over four seasons, we conducted 472 bird point count surveys and established 118 plots distributed across the Desert, Pre-Puna, Puna and High-Andean belts, where biotic, abiotic and anthropogenic factors were measured. We used mixed-effects models to estimate alpha diversity and multinomial Poisson mixture models to estimate species density, accounting for detectability. Species diversity and density increased until 3300 masl and then declined. This type of elevational pattern is characteristic of dry-based mountains, where environmental conditions are suitable at mid-elevations. Habitats shaped by traditional Aymara indigenous agriculture, associated with relatively high vegetation heterogeneity, hosted the highest values of bird diversity and density. Species turnover was structured by habitat type, while elevational ranges of most species were restricted to three relatively discrete assemblages that replaced each other along the gradient. Our study revealed a hump-shaped relationship between elevation and bird diversity and density in the Dry Tropical Andes Biodiversity Hotspot, supporting a diversity pattern characteristic of dry-based mountains of the world. Traditional Aymara agriculture may have constructed ecological niches for biodiversity at mid-elevations, enhancing vegetation heterogeneity, thus providing resources for resident and rare species. Increasing loss of traditional land-use may present a threat to the bird community in the Tropical Andes Hotspot.

Because of the significant impacts on both human interests and bird conservation, it is imperative to identify patterns and anticipate drivers of human–bird conflicts (HBCs) worldwide. Through a global systematic review, following the PRISMA 2020 guidelines, we analyzed the socioeconomic factors and bird ecological traits driving the degree of knowledge and extent of HBCs. We included 166 articles published from 1971 to 2020 in our analyses through which we built a profile of the socioeconomic conditions of 52 countries with reported conflicts and the ecological traits of the 161 bird species involved in HBCs. Although HBC expanded worldwide, it had the greatest impact in less‐developed countries (estimate 0. 66 [SE 0.13], p< 0.05), where agriculture is critical for rural livelihoods. Species with a relatively greater conflict extent had a relatively broader diet (estimate 0.80 [SE 0.22], p<0.05) and an increasing population trend (estimate 0.58 [SE 0.15], p<0.05) and affected human interests, such as agriculture and livestock raising. In countries with greater biodiversity, HBCs caused greater socioeconomic impacts than in more developed countries. Our results highlight the importance of understanding and addressing HBCs from multiple perspectives (ecological, sociocultural, and political) to effectively protect both biodiversity and local livelihoods.

The population of Tarapacá, northern Chile, is supplied with drinking water of underground origin. The objective of this study was to evaluate the chemical quality of water for human consumption in nine urban and rural locations and its compliance with current norms (temperature, salinity, alkalinity, dissolved majority ions, As and B). Geochemical classifications were deduced to consider the origin and relationships between waters. Moreover, five water stability indicators were evaluated to estimate potential corrositivity (B/Clratio, Cl -/SO 4 2ratio and Larson ratio) and calcareous inlays formation (Langelier Saturation Index and Ryzman Stability Index). The samples analyzed were determined had mild temperatures, slightly alkaline, with a wide range of values of salinity (74.7 -1287 mg L -1 ). The hydrogeochemical results confirmed four water types: Na + /HCO 3 --Cl --SO 4 2-, Na + /SO 4 2-, Na + -Ca 2+ /SO 4 2-, and Na + -Ca 2+ /Cl --SO 4 2-. The 168 samples reached 100% of the degree of compliance of NCh409, except in the wells of Colonia Pintados, where As concentration exceeded 13 to 30 times the norm. Sulphate and B exceeded international standards. The water taste deterioration can be attributed to high concentrations of SO 4 2-, Cl -, Ca 2+ , and B. Finally, water stability indexes determined the capacity for severe corrosively potential and formation of light calcareous deposits. The internal regulations of the country must harmonize and admit substances suggested by the WHO.

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