Interpreting past trophic ecology of a threatened species, kea (Nestor notabilis), from museum specimens

When ecosystems are under severe pressure or environments change, trophic position and intraspecific niche width may decrease or narrow, signalling that conservation action is required. In New Zealand, alpine and sub-alpine ecosystems have been extensively modified through farming since 19th century European settlement, with consequences for indigenous species such as the kea (Nestor notabilis). We investigated feather stable isotope values in the kea and predicted a lower trophic position in modern kea populations, to reflect reduced lowland habitat and a mixed diet with more plant material. We predicted that size and sex would influence trophic values in this sexually dimorphic species, with larger birds more likely to have a high protein diet. We examined potential dietary changes in 68 museum collected kea from 1880s to 2000s, first recording accession details including provenance and sex, and measuring culmen length. We used bulk carbon and nitrogen stable isotopes analyses (BSIA) ...