Seasonal and ontological variation in diet and age-related differences
in prey choice, by an insectivorous songbird
Abstract
The diet of an individual animal is subject to change over time, both in
response to short-term food fluctuations and over longer time scales as
an individual ages and meets different challenges over its life cycle. A
metabarcoding approach was used to elucidate the diet of different life
stages of a songbird, the Eurasian reed warbler (Acrocephalus
scirpaceus) over the summer breeding season of 2017. The faeces of
adult, juvenile and nestling warblers were screened for invertebrate
DNA, enabling identification of prey species. Dietary analysis was
coupled with monitoring of Diptera in the field using yellow sticky
traps. Seasonal changes in warbler diet were subtle whereas age class
had a greater influence on overall diet composition. Age classes showed
high dietary overlap, but significant dietary differences were mediated
through the selection of prey, i) from different taxonomic groups, ii)
with different habitat origins (aquatic versus terrestrial) and iii) of
different average approximate sizes. Our results highlight the value of
metabarcoding data for enhancing ecological studies of insectivores in
dynamic environments.