Suitable, reachable but not colonised: seasonal niche duality in an endemic mountainous songbird

摘要: The realized distribution of animals is often delimited by climatic factors which define, next to the specific habitat and food availability, their species-specific potential distribution. We studied environmental limi- tations affecting breeding wintering dis- tributions Citril Finch (Carduelis citrinella), one few endemic bird species European mountain ranges. To assess limits that shape seasonal distribution, we used models (SDMs) derived from macroclimate in combination with land cover information. Our data suggest a high congruence between modelled currently known sites, indicating level niche filling. unusual absence several suitable habitats at eastern northern range limit (Eastern Alps, Carpathians, Bavarian Forest, Harz Mountains, Fichtelgebirge, Krkonose Mountains) likely linked both missing resources restricted physiological migration capacities available grounds. Since accomplished migratory distances hardly exceed more than 500 km, it seems distance main areas too large for exceeding limits. discuss differences SDM outcomes when including distal predictor variables instead using proxi- mal predictors alone, highlight importance considering duality gain insights into complex effects