Alarming decline of the Little Bustard Tetrax tetrax in one of its two population strongholds in Sardinia, Italy

Abstract

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.

Satellite images reveal major discrepancies between mapped and operating wind turbines in a hotspot of wind energy development

“…Among birds, these include approx. 332-378 Griffon Vultures (Gyps fulvus) [18] and the last Italian declining population of Little Bustards (Tetrax tetrax) [19] , two species which are prone to collide with wind turbines due to their visual field [20] . Moreover, Sardinia hosts the critically endangered endemic Sardinian Long-eared Bat (Plecotus sardus) [21] , a decreasing population of red kite (Milvus milvus) [22] , a small reintroduced population of Bonelli's eagle (Aquila fasciata) [23] and the endemic Corsican finch (Carduelis corsicana).…”

Temporal trends of land-use favourability for the strongly declining little bustard: assessing the role of protected areas

“…The little bustard ( Tetrax tetrax ) is a farmland steppe bird strongly and negatively affected by recent agricultural changes in Europe ( Traba & Morales, 2019 ; Morales & Bretagnolle, 2022 ; Santangeli et al, 2023 ). This bustard occupies extensive, heterogenous farmland landscapes ( Morales, García & Arroyo, 2005 ; Faria & Silva, 2010 ) and can be an indicator of well conserved agricultural steppe ecosystems and an umbrella species for other steppe birds ( Morales & Bretagnolle, 2022 ; Morales, Merencio & García de la Morena, 2023 ).…”

“…The little bustard is in strong decline all over Europe ( e.g. , Morales & Bretagnolle, 2022 ; Santangeli et al, 2023 ) associated with increasing agricultural intensification ( Inchausti & Bretagnolle, 2005 ; Traba & Morales, 2019 ) which typically includes reduced fallow surface, increased irrigation, and monocultures leading to landscape simplification, as well as an increase in chemical inputs ( Matson et al, 1997 ; Emmerson et al, 2016 ; Stanton, Morrissey & Clark, 2018 ), all of which reduce habitat suitability. Some farming practices (such as fallow ploughing or night operations) are particularly detrimental for the little bustard, causing nest loss, nestling and adult mortality ( Morales et al, 2013 ; Bretagnolle, Denonfoux & Villers, 2018 ; Silva et al, 2022 ), while the use of agrochemicals ( i.e., fertilizers or pesticides) may have effects on food abundance.…”