Grazer density and songbird counts in a restored conservation area

PeerJ. 2021 Jan 5:9:e10657. doi: 10.7717/peerj.10657. eCollection 2021.

Abstract

Grazing by large herbivores is increasingly used as a management tool in European nature reserves. The aim is usually to support an open but heterogeneous habitat and its corresponding plant and animal communities. Previous studies showed that birds may profit from grazing but that the effect varies among bird species. Such studies often compared bird counts among grazed areas with different stocking rates of herbivores. Here, we investigated how space use of Konik horses and Highland cattle is related to bird counts in a recently restored conservation area with a year-round natural grazing management. We equipped five horses and five cattle with GPS collars and correlated the density of their GPS positions on the grazed area with the density of bird observations from winter through the breeding season. We found that in the songbirds of our study site, both the overall density of bird individuals and the number of species increased with increasing density of GPS positions of grazers. Correlations of bird density with horse density were similar to correlations with cattle density. Of the eight most common songbird species observed in our study area, the Eurasian Skylark and the Common Starling had the clearest positive correlations with grazer density, while the Blackbird showed a negative correlation. Skylarks and Starlings in our study area thus seem to profit from year-round natural grazing by a mixed group of horses and cattle.

Keywords: Highland cattle; Konik horse; Large herbivore; Natural grazing; Songbird; Space use.

Grants and funding

This work was supported by the Fondation de bienfaisance Jeanne Lovioz, the Foundation Emilia Guggenheim-Schnurr, the Ornithologische Gesellschaft Basel, the Swiss Association Pro Petite Camargue Alsacienne, the Foundation Wolfermann-Nägeli, the Foundation Frey-Clavel, and the MAVA Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.