Abstract
Understanding the role diet plays in the structure of food webs is
vital, and dietary knowledge is key for conservation management success.
There is limited knowledge of the diets of woodland bird species, due
largely to difficulties in accurately identifying plant and invertebrate
taxa being consumed. Here, we show the effectiveness of multi-marker
faecal metabarcoding to provide the most in-depth dietary analysis of a
generalist passerine, the Hawfinch (Coccothraustes
coccothraustes , Linnaeus), to date. Faecal samples were obtained from
2016-2019 from Hawfinch populations prior to and during the breeding
season throughout the UK. DNA was extracted from 263 samples and
amplified using Internal Transcribed Spacer 2 (ITS2) and cytochrome C
oxidase subunit I (COI) barcodes. Using high-throughput sequencing
(HTS), we identified 49 and 97 ITS2 and COI zero radius operational
taxonomic units (zOTUs) respectively which equated to reputed dietary
items. The herbivorous element of Hawfinch diet was dominated by
naturally occurring taxa such as beech (Fagus sylvatica ,
Linnaeus), hornbeam (Carpinus betulus , Linnaeus) and oak
(Quercus sp., Linnaeus). The most taxon rich and commonly
recorded invertebrate taxon identified was Lepidoptera. We found
Hawfinch diet varied spatially, as well as between sexes. Hawfinch
showed broad dietary plasticity and utilised multiple resources within
their foraging environments. Our study shows the potential of
multi-marker DNA metabarcoding to reveal subtle dietary differences, but
also highlights the challenges of studying omnivorous species using
metabarcoding methods.
Keywords