Metabarcoding insights into the diet and trophic diversity of six declining farmland birds

Abstract

Knowledge of feeding ecology of declining species, such as farmland birds, is essential to address their conservation requirements, especially when their habitats are suffering important reductions of trophic resources. In this study, we apply a metabarcoding approach to describe the diet composition of six of the most significant farmland birds inhabiting European cereal pseudo-steppes: little bustard, great bustard, pin-tailed sandgrouse, black-bellied sandgrouse, red-legged partridge, and common quail. We further studied seasonal diet variations (autumn to spring) in all species but the common quail, whose diet was studied during spring and summer. We show that study species´ diets mostly consisted of plants, although in the case of little bustard and great bustard arthropods are also highly relevant. Among arthropods, we found high proportions of thrips, arachnids, and springtails, which were previously unreported in their diet, and some taxa that could be used as antiparasitic food. Moreover, we report that little bustard’s diet is the least rich of that of all studied species, and that diet of all these species is less diverse in winter than in autumn and spring. Diet composition of these declining species supports the importance of natural and semi-natural vegetation and landscape mosaics that can provide a wide variety of arthropods, plants, and seeds all year-round.

Comparison of destructive and nondestructiveDNAextraction methods for the metabarcoding of arthropod bulk samples

“…In particular, assessments from highly diverse terrestrial insect samples seemed incomplete or resulted in different diversity patterns when DNA extracts from preservative ethanol were directly compared to tissue extracts, which highlights the need for further experimental testing of nondestructive DNA metabarcoding approaches (Marquina, Esparza‐Salas et al, 2019; Zenker et al, 2020). Despite these methodological inconsistencies, DNA metabarcoding is already widely used in various large‐scale studies as the tool of choice for diet studies, biodiversity assessment and monitoring (Bonato et al, 2021; Cabodevilla et al, 2021; Ingala et al, 2021; Lozano Mojica & Caballero, 2021; Svenningsen et al, 2021). The processing of large sample numbers requires fast, reliable and cost‐efficient protocols.…”

Simultaneous analysis of the intestinal parasites and diet through eDNA metabarcoding

“…2019), this percentage could be useful for comparative studies (Cabodevilla et al . 2021). However, it should be noted that this is a representation and not a quantification and that we do not know the behavior of this mini‐barcode with respect to plants and animals.…”

Biased adult sex ratios in Western Europe populations of Little BustardTetrax tetraxas a potential warning signal of unbalanced mortalities

“…2020). Habitat loss and/or degradation has been linked to agricultural intensification (Silva et al 2017, García de la Morena et al 2018, Bretagnolle et al 2018, Traba and Morales, 2019), including increasing application of agro-chemicals, which reduce food availability for declining steppe birds (Jiguet 2002, Cabodevilla et al 2021). Agricultural abandonment and urbanisation have also probably contributed to the species’ decline (Suárez 2004, Oñate 2005, Arroyo et al .…”