Cygnus sumnerensis ssp. sumnerensis Forbes

New Zealand Swan (Cygnus sumnerensis ssp. sumnerensis)

The New Zealand Swan was described in 1890 based on subfossil remains, which, however, were apparantly lost later. The name was then declared a nomen nudum and the species was redescribed (using only bones from Chatham Islands birds) as Cygnus chathamensis Oliver in the 1950s. [1]


The species was for some time thought to have been identical to the Australian Black Swan (Cygnus atratus Latham) (see photo), a species that was deliberately introduced to New Zealand in 1864, though there is evidence for self-introduction around this time and possibly prior to this. [1]

The remains of the New Zealand Swan were compared to those of the Australian species and it was found that both differed significantly from each other by their size, but only in 2017 DNA samples were compared which showed that both swan forms were indeed distinct from each other. The New Zealand Swan was closely related to the Australian Black Swan but differed from it by being larger and more stoutly build, it is furthermore split into two subspecies, one, the nominate, formerly inhabiting the main islands and one having been endemic to the Chatham Islands. [1]



[1] Nicolas J. Rawlence; Afroditi Kardamaki; Luke J. Easton; Alan J. D. Tennyson; R. Paul Scofield; Jonathan M. Waters: Ancient DNA and morphometric analysis reveal extinction and replacement of New Zealand’s unique black swans. Proceedings of Royal Society B. Biological Science 284: 20170876. 2017


Australian Black Swan (Cygnus atratus Latham)

Photo: Anagoria

(under creative commons license (3.0))


edited: 17.04.2019