Urban bird predation on artificial caterpillars

We established our study sites in the cities of Basel, Lugano and Zurich, and their peri-urban forests. We characterised urban tree cover of each city using a rectangular grid with squares of 100x100 m. Within each square, we measured the area covered by urban trees using the European Union's Copernicus Land Monitoring Service information, Urban Atlas Street Tree Layer 2018 [https://doi.org/10.2909/205691b3-7ae9-41dd-abf1-1fbf60d72c8c](https://doi.org/10.2909/205691b3-7ae9-41dd-abf1-1fbf60d72c8c). Then we assigned each square to four categories of urban tree cover that roughly represented the main types of urban uses: 1) low cover, industrial/commercial areas, 0-20% tree cover; 2) intermediate cover, residential areas, 20-40% tree cover; 3) high cover, urban parks and cemeteries, 40-60% tree cover; 4) peri-urban forests (natural/semi-natural forests), 60-100% tree cover. -br/--br/- Our study sites consisted of eight 1.2 km-long transects in each city, equally distributed across the four tree cover categories. We designed an experimental measurements of bird predation rate on herbivore insect larvae using artificial caterpillars. They mimicked a variety of common, cryptically-co