Largest swan ever

The largest species of swan ever was the aptly named giant swan (Cygnus falconeri), a land-feeding species that lived on Malta and Sicily during the mid-Pleistocene (Chibanian) geological age, approximately 770,000–126,000 years ago. Based upon the dimensions of fossil bones disinterred so far, scientists estimate that this species probably resembled a scaled-up whooper swan (C. cygnus), weighing about 16 kg (35 lb 4 oz) and sporting a wingspan of about 3 m (9 ft 10 in). In overall dimensions, it was probably a third larger than the mute swan (C. olor), and was therefore almost certainly flightless.

Another extinct species of giant swan is the New Zealand black swan or pouwa (C. sumnerensis), formerly native to South Island and the Chatham Islands, which is believed to have survived until as recently as c.1450 CE on the former and 1650 CE on the latter. Its extinction is blamed upon over-hunting by the first Polynesians, and their attendant rats that would have eaten its eggs. Standing 1 m (3 ft 3 in) tall, and weighing around 10 kg (22 lb), the pouwa was much more robust than the present-day Australian black swan (C. atratus), weighing around 6 kg (13 lb 4 oz), which was introduced into New Zealand during the 1860s (as well as via vagrant arrival there of its own accord). Even so, it was long deemed to be merely a New Zealand variant of the latter species until analysis of its DNA extracted from its subfossil remains confirmed in 2017 that the pouwa was a valid albeit closely related species in its own right after all.

Interestingly, although not as heavy, the giant swan would have been taller than Malta's famous prehistoric dwarf elephant (Palaeoloxodon falconeri), which co-existed with it but stood less than 1 m (3 ft 3 in) at the shoulder.

The largest living species of swan (and indeed largest living waterfowl overall) is a record held jointly by two species: the mute swan (Cygnus olor), which is heavier, and the trumpeter swan (C. buccinator), which has a greater wingspan. Native to the UK and much of Eurosiberia, the mute swan has a typical weight in adult males or cobs (which are slightly larger than adult females or pens) of 15 kg (33 lb), but one exceptionally heavy wild Polish cob weighed 22.5 kg (49 lb 10 oz) at the height of summer, as documented by German naturalist Walter von Sanden in 1935. Native to North America but most common in Alaska, the trumpeter swan sports a wingspan of up to 250 cm (8 ft 2 in), and is deemed by some ornithologists to be conspecific with the Eurasian whooper swan (C. cygnus).