Avian diversity and trait dataset from native and non-native tree stands across Central Europe

This dataset contains plot-level environmental variables, bird community records, and standardized breeding-evidence categories collected in native and non-native forest stands in the northernmost Pannonian Basin (western Slovakia). Data were collected during two breeding seasons (2023–2024) using a standardized point-count protocol applied in a twin-plot design, where each native stand was paired with a nearby non-native stand dominated by Robinia pseudoacacia (black locust) or Populus × euramericana clone I-214 (hybrid poplar). Table 1 provides plot-level descriptors, including stand origin, age, tree-species composition, slope, aspect, elevation, and geographic coordinates. Table 2 lists all bird observations from point counts, including species identity, abundance, plot codes, survey timing, and species-level ecological traits (body size, clutch size, number of broods, incubation period, lifespan, nest type, migration strategy, and diet). Table 3 contains explanation of a standardized scheme for classifying breeding evidence, covering categories from possible to confirmed breeding based on behavioral and nest-related criteria. This dataset supports spatial and temporal analyses of forest bird communities across matched twin-plots that differ in tree-species composition (near-natural vs. non-native) but share similar structural conditions (age, slope, aspect, elevation). Explanations: Table 1: Code – twin-plot identifier; Age – average age of dominant tree species; Composition – proportion of dominant species (abbreviations: BL = Robinia pseudoacacia; BA = Alnus glutinosa; BP = Populus nigra; EA = Fraxinus excelsior; EB = Fagus sylvatica; EH = Carpinus betulus; EO = Quercus robur; ES = Populus tremula; EWE = Ulmus laevis; FE = Ulmus minor; FM = Acer campestre; I-214 = Populus × euramericana I-214; SL = Tilia cordata; SO = Quercus petraea; SP = Pinus sylvestris; WP = Populus alba; WW = Salix alba; SCH = Cerasus avium). Table 2: Code – twin-plot identifier; Origin – N = native, A = alien (non-native); Abundance – number of individuals; Breeding category – A = possible, B = probable, C = confirmed, M = migration/overflight; ecological traits as listed above. Table 3: Breeding categories (A–C), their codes, and assigned field-based criteria.