Interpreting past trophic ecology of a threatened alpine parrot, 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 subalpine 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 isotope analyses (BSIAs) of feathers and a further feather subset using compound-specific stable isotope analyses of amino acids (CSIA-AA) to obtain isotopic values and estimate trophic position. BSIA showed δ