Observations of avifauna on Rēkohu / Wharekauri / Chatham Island, Chatham Islands group, in February 2023

Abstract
Rēkohu / Wharekauri / Chatham Island (hereafter Rēkohu) is the largest island in the Chatham Islands group, 800 km east of the Te Wai Pounamu / South Island, Aotearoa / New Zealand. This island has an avifauna of 170 taxa. Here, we present a list of bird species encountered during an eight-day undergraduate field trip in February 2023. We also provide the first attempted comprehensive listing of avifauna of the island. Based on visual encounters or via calls heard, we encountered 38 species of bird (two seabirds, eight coastal birds, six freshwater birds and 22 terrestrial birds) across 13 locations over six days. The most common species sighted were common starlings (Sturnus vulgaris vulgaris), followed by white-fronted terns (Sterna striata) and black swans (Cygnus atratus). We encountered a Chatham Island tūī (Prosthemadera novaeseelandiae chathamensis) in Nikau Bush Reserve, c.35 km north of the translocated population in Awatotara Valley. We also present the first list of bird species for Motuhinahina and a nearby limestone rock stack in Te Whanga Lagoon. Birds encountered there included Chatham Island shag (Leucocarbo onslowi), Pitt Island shag (Phalacrocorax featherstoni), Buff weka (Gallirallus australis hectori) and New Zealand little penguin (Eudyptula minor minor). We formally report the presence of feral emu (Dromaius novaehollandiae), including chicks, at Te Matarae, where there is self-sustaining population following their release to the wild years ago. In previous observations, feral chicken (Gallus gallus gallus) and turkey (Meleagris gallopavo) were ‘semi-wild’ on the basis that observations made of these species were well outside sites of human habitation. In the case of turkey, they are in the process of self-establishing. We suggest a full census is required to determine the status of these populations, particularly emu. As the emu population is self-sustaining, they should be considered as a new addition not only to the avifauna of the Chatham Islands group but to Aotearoa / New Zealand.