Population productivity and late breeding habitat selection by the threatened Little Bustard: the importance of grassland management

Abstract

SummaryWe investigated population productivity and habitat selection of the Little BustardTetrax tetraxin the late breeding period, in grassland-dominated landscapes of south-west Iberia. Specifically, our goals were to investigate how these parameters are influenced by the management of (1) grazing and (2) hay production. We conducted bird counts from 22 June to 4 July (2012 to 2016) using low speed 4x4 car surveys. The relationship between the density of the species, population productivity and farm management (grazing and haying) was evaluated using Generalized Linear Mixed Models and Kruskal-Wallis tests. Male and female densities were significantly higher in short vegetation compared to all other types of vegetation considered, but population productivity was similar in short and medium vegetation. Hay stubbles were found to be unattractive for the species. The availability of suitable habitats depends on the timing of grazing, notably of seasonal (spring) grazing. Species density was higher in fields ungrazed during winter and with moderate to high stocking rates in spring (around 0.8 LU/ha or higher), depending, at least for males and females, on each year’s weather characteristics. We conclude that low to moderate stocking rates during winter and spring are essential to ensure successful breeding and thus population persistence. Current levels of haying in our study area are detrimental for the species’ conservation.