The potential of White Stork (Ciconia ciconia) nest lining to evaluate the functional diversity of Coleopteran fauna

Abstract Collecting arthropod samples is usually very invasive because these organisms die during sampling, and it is hard to obtain a statistically robust sample. The availability of arthropods is critical for the survival of the youngest White Stork ( Ciconia ciconia ) nestlings and impacting the productivity of this species populations; thus, the species is a strong predator of a variety of epigeic insects. At the time of progressive drying of climatic conditions due to climate change or/and in dry habitats replacing wetlands, the role of termophilic taxa as certain Coleoptera in nestling diet is often underestimated. Here, we evaluated the Coleopteran component of the diet of the White Stork nestlings using the nest lining material consisting of fragmented remains of regurgitated pellets and soil-like material, and related the community indices of Coleopteran fauna to the landscape structure within a radius of 2.5 km around nests. In eight nests collected in SE Poland, we found a massive accumulation of beetle remains representing 32,277 individual Coleopteran prey items, from which 17,252 were identified to the family level. Our analysis showed a significant relationship between the landscape structure and beetle communities, as well as the abundance of dominant prey taxa and the share of three major functional guilds (herbivores, scavengers, and predators). The significant contribution of scavengers was associated with a high proportion of forests around the nest and decreased with increasing proportion of arable lands and mixed crops, while the high proportion of herbivorous and predatory beetles was associated with a high share of arable lands. We showed that the analysis of nest lining material, mainly the remains of pellets, provides taxonomically informative data on beetle communities and can be a valuable tool in bioindicative assessments of Coleopteran biodiversity. Given the widespread nesting of White Stork near landfills (increasing the productivity of their local populations), further studies assessing the role of the Coleopteran component, particularly the contribution of necrophagous or saprophagous beetles, in the diet of early nestlings of this bird species are essential.