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Predation on artificial ground nests in birch forests fragmented by spruce plantations
- Einarsen, Gøøril, Hausner, Vera H., Yoccoz, Nigel G., Ims, Rolf A.
- Écoscience 2008 v.15 no.2 pp. 141-149
- Betula pubescens, Corvus corone, Lagopus lagopus, Lyrurus tetrix, Picea abies, Vulpes vulpes, buildings, crows, forests, habitat fragmentation, land use, landscapes, nests, plantations, planting, predation, predators, roads, spatial variation, Norway
- Spruce planting (Picea abies) in coastal birch forests (Betula pubescens) of northern Norway could influence ground-nesting species such as willow ptarmigan (Lagopus lagopus) and black grouse (Tetrao tetrix). Predator-specific predation rates on baited trackboards were therefore studied in 3 successional edge gradients: birch forest adjacent to (1) closed spruce plantations, (2) open spruce plantations, and (3) clearings. We also examined the influence of 2 types of landscape-level variables on predation rates: the distance from sampling location to the nearest roads and buildings and the land use composition within a 1-km radius of the sample. Predation rates were dominated by 2 generalist species: red fox (Vulpes vulpes) (19.2%%) and hooded crow (Corvus corone cornix) (7.5%%). Predation appears dependent on the successional stage of spruce plantations, with areas near clearings (63.5%%) and open spruce plantations (59.8%%) experiencing higher predation pressures than closed spruce plantations (45.3%%). However, predation rates were highly variable among landscape blocks. Neither landscape nor vegetation variables could explain this block-level variation. We discuss alternative mechanisms that could explain differences between landscape blocks, but further studies are needed to understand the spatial heterogeneity of predators at larger scales.Nomenclature: Mitchell, 1974; Svensson et al., 1999; Macdonald, 2002.