Effect of Transhumant Livestock Grazing on Pseudo-Alpine Grassland Bird Communities

Transhumance is a traditional animal husbandry system, but its effects on grassland avian communities have not been dealt with in depth. In this study, we quantified the influence of transhumance on the grassland avifauna, in representative pseudo-alpine grasslands with no (NGG), low (LGG), and high (HGG) grazing intensity in the Pindos Mountains, Central Greece. Two point count surveys were conducted within 20 sites in each grassland during the bird breeding season of 2016. We assessed bird diversity indices and accounted for whether the recorded habitat and topographic variables were involved in their variation. A total of 25 bird species were recorded, with the grazed grasslands supporting the most species of high conservation value, while the NGG showed the highest bird diversity. Bird species richness and diversity increased with the decrease of vegetation height, vegetation height heterogeneity, and the increase of rock cover. Bird communities exhibited different patterns among the three grazing regimes and specific bird species of high conservation value appeared to prefer different grasslands. Six species preferred HGG, one preferred LGG, while two preferred NGG. Our study highlights the necessity of heterogeneous pseudo-alpine grasslands with short and tall grass areas in order to maintain highly diverse bird communities.