Largest swan

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).

The weight recorded for the aforementioned Polish cob is the heaviest verified for a specimen belonging to any species of flying bird. Having said that, however, it has been questioned whether on account of its extreme weight this particular specimen was actually capable of flight. Excluding exceptional specimens like this one, the heaviest species of modern-day flying bird is the kori bustard (Ardeotis kori) of East and southern Africa, the heaviest verified specimen of which weighed 40 lb (18.14 kg), as documented in 1936.

Less than 1 million years ago, a species of swan existed that dwarfed both the mute swan and the trumpeter swan. Native to Malta and Sicily where various fossil remains have been found, this was the giant swan (C. falconeri), existing during the mid-Pleistocene around 770,000–126,000 years ago. Land-feeding and probably flightless, it is believed to have weighed around 16 kg (35 lb 4 oz), with a wingspan of about 3 m (9 ft 10 in).