Local population decline of the threatened Lesser Grey Shrike Lanius minor is linked to the modernisation of the rural landscape

Abstract

Summary Landscape changes and the intensification of agriculture in recent centuries were largely responsible for the dramatic decline in the biodiversity of farmlands. Rural settlements have also been subject to radical changes due to modernisation, but their impact on bird populations is poorly quantified. The Lesser Grey Shrike Lanius minor is a threatened farmland bird and already extinct in many areas. We monitored a population of this long-distance migrant in a traditional farming area in the Poľana Mountains (central Slovakia) in three breeding seasons (1996, 2016, and 2021). We analysed the impact of the increase in number of modern habitations and the decrease in traditional farmsteads on the population decline. The number of breeding territories decreased from 73 in 1996 to 38 in 2016 and 22 in 2021. As the population has declined, the breeding area has also shrunk significantly. While there were no modern homesteads in the breeding territories in 1996, by 2021 their number had increased to the number of traditional farmsteads. Building a single modern house in a territory reduced the probability of nesting to about 6%, and this effect was also seen when one or two farms were still present (17% and 40%, respectively). An additional modern homestead in the territory reduced the nesting probability to almost zero, even if a farmstead was already present. In this long-term empirical study, we identified these changes as a local threat factor for the species studied. The results presented can help in the design and implementation of conservation measures in traditional farming landscapes.