Variable contribution of functional prey groups in diets reveals inter- and intraspecific differences in faecal concentrations of essential and non-essential elements in three sympatric avian aerial insectivores: A re-assessment of usefulness of bird faeces in metal biomonitoring

摘要: Abstract Aerial insectivores through their insect diet can contribute to biotransfer of elements across habitats. We investigate the relationship between dietary composition as expressed by contributions six functional invertebrate prey groups (primarily agriculturally subsidised invertebrates characteristic agricultural areas in temperate regions Europe) and concentrations essential (Na, K, Ca, Mg, Fe, Cu, Zn, Mn, Co) non-essential (As, Cd, Pb) environmental concern faeces nestlings three species avian aerial – Common Swift Apus apus , Barn Swallow Hirundo rustica House Martin Delichon urbicum which breed sympatrically use apparently similar resources flying prey. There were significant differences for 7 12 (Ca, Co, As, Pb, Cd); these attributable variable composition, even though varied enormously faecal samples from individual species. Partial correlation analysis biomass (expressed mg dry weight) showed highest number relationships toxic metals Pb Cd). The results General Regression Model explaining element revealed different explanatory power effects PCA (of groups) scores. A fit GRM was obtained Cd) Swallows, 2 (Cu, As) Martins 1 (Mn) Swifts. Overall, confirmed our predictions that consumed coprophilous taxa insects crop habitats positively correlated with elements. Unexpectedly, however, those Swifts) contained many oil-seed rape pests had lower Cd levels a higher As level. Our study implies cross-boundary transfer contaminants, primarily elements, aerially foraging birds considerable accumulation has potential consequences local biogeochemical cycle quality.