Anas chathamica (Chatham Island Duck)

[Melanie]

Feeding ecology analysis supports a marine diet in the extinct Chatham Island Duck (Anas chathamica)

ABSTRACT

The Chatham Island Duck, Anas chathamica, is one of many New Zealand bird species that became extinct after Polynesian arrival. The Chatham Island Duck was a large flightless bird, with salt glands on its skull, which led to the hypothesis that it lived in a marine habitat. We tested this hypothesis using a combination of stable isotope analysis (carbon and nitrogen) and analysis of morphoanatomical features. We also conducted a comparative analysis with other anatids from the Chatham Islands and New Zealand. Furthermore, we trialled the non-destructive technique of portable X-ray fluorescence (elemental composition of bones) to assess whether it can be helpful for reconstructing the ecology and habitat of extinct species. We obtained data from museum specimens: 12 samples of A. chathamica and 55 of other anatids for isotope analysis; and 23 samples of A. chathamica and 63 of other anatids for X-ray fluorescence. Results from isotope analysis, supported by anatomical features, show that A. chathamica had a more fully marine diet than previously hypothesised, mainly composed of invertebrates. The large body size of A. chathamica is possibly related to territoriality and combat, which is also supported by the presence of carpal weaponry. Our data demonstrate the importance that the marine environment likely played in the life of this extinct species, while highlighting the key role natural history collections can have in ecological studies.

www.tandfonline.com/doi/full/10.1080/01584197.2021.1939719?src=

[Sebbe]

The radiation of Austral teals (Aves: Anseriformes) and the evolution of flightlessness.

The origin and evolution in the Southern Hemisphere of the Austral teals, consisting of the grey-teal and brown-teal species complexes, remains poorly understood owing to limited molecular data. With the group containing multiple independent examples of flight loss, understanding the evolutionary history of the group is of significant interest for functional genomic studies into the evolution of flightlessness. Here, we present the first whole-mitogenome-based phylogeny of the Austral teals. We show that the group diverged from a common ancestor with mallards in the late Miocene and soon after radiated into the brown-teal and grey-teal lineages, in addition to the widely distributed pintails and green-winged teals. The brown-teal species complex, which includes the volant brown teal, the flight-impaired, sub-Antarctic Auckland Island teal, and the flightless, Chatham Island and sub-Antarctic Campbell Island teals, radiated within the past 0.9–1.8 Myr. The divergence of the extinct Chatham Island teal and the colonization of the Auckland and Campbell Islands occurred from mainland New Zealand. Morphological changes towards flightlessness are also present in the volant brown teal on mainland New Zealand, suggesting that this group was on the pathway to flightlessness, a trend that accelerated in some insular island lineages.

academic.oup.com/zoolinnean/article/201/4/zlae036/7729571