Avian predators in a meadow landscape: consequences of their occurrence for breeding open-area birds

We examined the occurrence of six species of meadow birds (four wader species and two songbird species) in relation to the distance to the nest location of an avian predator (three species). We related our findings to the degree of openness of the landscape in which this avian predator nest was located. The degree of openness varied from very open to very closed, depending on the number of view-obstructing landscape elements in the landscape (none or very few in open ones, but completely covered with forest or built-up area in very closed landscapes). We used a dataset containing nesting locations of meadow birds and predators in the province of Gelderland, the Netherlands, allowing us to perform the analysis on three grid cell sizes (100x100 m, 250x250 m and 500x500 m). Our results show that, for each grid cell size, all meadow bird species showed highest nesting densities in open landscapes. Lowered densities were found around occupied nests of avian predators, irrespective whether the predator's nest was situated in an open or closed landscape. The preference of meadow birds for open landscapes away from predator's nests suggests that a large visibility, that allows them to scan for predators to be able to chase them away in time, is an important habitat requirement for meadow birds to select a nest site. It also suggests that openness of the landscape, independent from the presence of occupied predator's nests, is a factor in selecting a nest site. In contrast, for two out of three species of avian predator, we found that they chose more closed landscapes to nest because these species nest in landscape elements like wood lots and lone trees which make the landscape more closed by definition. For the third avian predator species, the grid cell size was probably too small to find a consistent result, as that species has territories larger than even the largest grid cell size we used.