More waterfowl weirdness…
Most waterfowl can walk fine on land, and the majority of species are pretty agile in terms of their terrestrial abilities. But some species are so specialised for life on water, and have their legs placed so far back on their bodies, that any terrestrial abilities are poor, if not hilarious. One often reads of how divers (or loons) are only able to move on land with an awkward shuffle; less well known is that some waterfowl are pretty much the same.
One of the weirdest of waterfowl has to be the Musk duck Biziura lobata [image above from wikipedia]. This is a lekking species that shows extreme size dimorphism: males can be about three times larger than females (males can weigh as much as 3.8 kg, and females can be as small as 993 g). This is one of the biggest sexual size differences reported among birds (McCracken et al. 2000). Males really do smell strongly of musk. This emanates from the uropygial glands and is particularly strong during the breeding season. They’re also notable for having a weird, pendulous dewlap hanging from the lower jaw [image below ©, by crookrw, from the TOL page].
Musk duck of both sexes sit particularly low in the water, often lurking like submarines. Apart from when females clamber onto their floating nests, and when they’re in flight (they fly fairly often and are perfectly good at it), they’re never off the water. Musk duck can thus be considered completely aquatic: they never go on land. If captured and dumped on land, they can only slither along on their bellies like seals (Frith 1982). We all associate waterfowl with water, but I assume that few people realise that some waterfowl are this aquatic: like, fully aquatic.
Unsurprisingly perhaps, Biziura is a controversial duck. It has often been regarded as a stiff-tailed duck (an oxyurine), and even as particularly close to Oxyura (e.g., Livezey 1997). However, some workers have argued that this position is incorrect and that the similarities shared by Biziura and Oxyura to the exclusion of other oxyurines are convergences (McCracken et al. 1999); others have even found Biziura to be outside of Oxyurinae altogether, and even outside the anatid clade that includes oxyurines, tadornines and anatines (Worthy & Lee 2008). A slightly larger species – B. delautouri – formerly inhabited New Zealand (Worthy 2001) [image below from wikipedia].
For previous Tet Zoo entries on waterfowl see…
- Tet Zoo picture of the day # 10 (on Swan goose)
- 2007: a good year for terror birds and mega-ducks
- Meteoroid vs goose… again
- Attack of the flying steamer ducks
- STOP ‘feeding’ the ducks
- Harbour seal kills and eats duck
- Ridiculous super-elongate, coiled windpipes allow some birds to function like trombones – - or is it violins?
- Duck humps dog, and other stories from the world of waterfowl sex
- Lo, for I have seen the Meller’s duck, and it was good
- The Madagascar pochard returns (again)
- Pink-headed duck and Red-crested pochard: who would win in a fight?
- Duck sex: to interfere, or to watch?
- Can you raise reindeer on goose shit? Amazing waterfowl facts part I
- Death by toxic goose. Amazing waterfowl facts part II
- Detachable wing-daggers. Amazing waterfowl facts part III
Refs – -
Frith, H. J. 1982. Waterfowl in Australia. Angus & Robertson Publishers, London.
Livezey, B. C. 1997. A phylogenetic classification of waterfowl (Aves: Anseriformes), including selected fossil species. Annals of Carnegie Museum 66, 457-496.
McCracken KG, Harshman J, McClellan DA, & Afton AD (1999). Data set incongruence and correlated character evolution: an example of functional convergence in the hind-limbs of stifftail diving ducks. Systematic biology, 48 (4), 683-714 PMID: 12066296.
- ., Paton, D. C. & Afton, A. D. 2000. Sexual size dimorphism of the Musk duck. The Wilson Bulletin 112, 457-466.
Worthy, T. H. 2002. The New Zealand musk duck (Biziura delautouri Forbes, 1892). Notornis 49, 19-28.
- . & Lee, M. S. Y. 2008. Affinities of Miocene waterfowl (Anatidae: Manuherikia, Dunstanetta and Miotadorna) from the St Bathans Fauna, New Zealand. Palaeontology 51, 677-708.