Landscape changes associated to wind farm implementation increase predation on artificial ground-nests

Abstract

The effect of wind farms on birds has received considerable attention. Potential indirect impacts associated to these infrastructures include the attraction of predators that may increase nest predation rate, especially in ground-nesting species. In this work, we investigated artificial groud-nest predation at shrub-steppes in the presence and in the absence of wind farms. For that, we placed 18 sampling stations (11 in the absence and 7 in the presence of wind farms), comprising 9 artificial nests each. Artificial nests were placed in the same location at the beginning and at the end of the breeding season (April and June 2016). Nest predation events were recorded after twelve days exposure, average incubation period of small ground-nesting species inhabiting in the study area. We fitted a Generalized Mixed Effect model (1- predated, 0- non-predated; log link function) and nested effects were analysed incorporating sampling station and nest identifier as random factors, the latter in order to account for repeated-measures design. In addition, we incorporated the following fixed factors: i) month (April/June); ii) the covariate ‘wind farm’ (presence/absence); iii) landscape features in a 500 metres buffer around each sampling station (crop, tree and road surface); and iv) four Principal Components summarizing the microhabitat around each artificial nest, which was measured in a 1x1 metres quadrat. Predation rate was higher at the end than at the beginning of the breeding season (22.5% and 13.6%, respectively). The likelihood of predation was positively related to crop and road surface, being the latter linked to wind farms occurrence. Microhabitat variables around each artificial nest and the presence of wind farms did not influence predation rate. We conclude that roads, a landscape alteration mainly associated with wind farm implementation, increase predation rate on artificial nests since they ease the movement of terrestrial generalist predators. These results highlight the indirect impact that wind farms may have on ground-nesting species, which could compromise their breeding success and, therefore, population viability. An increase on predation rates in the vicinity of wind farms, could be partially explaining the negative impact of these infrastructures on the abundance, occurrence and population trends of small passerine birds[1].

[1] Gómez-Catasús, J., Garza, V. & Traba, J. (2018) Effect of wind farms on small passerine birds: occurrence, abundance and population trends of a threatened species, the Dupont’s lark Chersophilus duponti. Journal of Applied Ecology.