Tetrapod Zoology

I like ducks, and I particularly like steamer ducks. Again, here we revisit some Tet Zoo ver 1 text that was originally published in 2006 as part of the Ten Birds Meme.

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The most widely distributed of the four Tachyeres species*, the Flying steamer duck T. patachonicus inhabits both the fresh and marine waters of the Falklands and southern Patagonia and Tierra del Fuego. While all other steamer-ducks are flightless, T. patachonicus is (obviously) not, and in contrast to its flightless relatives it has proportionally bigger pectoral muscles and lower wing loadings. But what makes the species especially interesting is that some males within the species actually have wing loadings that are too high to permit flight, and are thus flightless (Humphrey & Livezey 1982, Livezey & Humphrey 1986). So, within a single species, there are both flighted and flightless individuals. It is almost as if the species is poised in the transition to full flightlessness, and indeed both morphological and genetic studies (Corbin et al. 1988) agree that T. patachonicus is the most basal member of its otherwise flightless genus. Flighted and flightless individuals are known to have also occurred in some recently extinct anseriform species, incidentally.

* One species, T. leucocephalus, was only described in 1981.

But there’s more. Steamer-ducks are notoriously pugnacious. Heavy-bodied and robust compared to other ducks, they have tough skin, a massive head and neck, and are equipped with keratanised orange knobs on the proximal parts of their carpometacarpi. Both sexes use these wing knobs in territorial fights and displays. Fighting males grab each other by the head or neck and then whack each other vigorously with the wing knobs, and fights can last for up to 20 minutes. Both birds sometimes submerge during the fight, and come up still fighting. This reminds me of scenes in films where super-heroes and villains (e.g., Spider-man vs Doc Oc) fall off buildings together and continue to battle even while plummeting toward the ground, but that’s just me. An aggressive steamer-duck approaches an ‘enemy’ by either adopting the so-called submerged sneak posture (only the top of the head and back and tail tip are visible), or by ‘steaming’ noisily across the surface (the ducks charge at speed, throwing their wings like the paddles of a paddle-steamer, hence the vernacular name).

Here’s where things get especially cool. Other waterbirds are shit-scared of steamer-ducks, and ‘mass spooks’ of other duck species, grebes and coots have been recorded when these birds saw or heard the local T. patachonicus. You see, they attack and kill other waterfowl. A particularly detailed steamer-duck attack on a Shoveler Anas platalea was recorded by Nuechterlein & Storer (1985a), and I here summarise the account they describe on p. 89.

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A male steamer-duck caught a male shoveler by the neck and began pounding it with its wing knobs [adjacent photo from Arthur Grosset's Birds]. The female steamer-duck displayed excitedly nearby. The shoveler was held beneath the water, then yanked up and beat some more. The male steamer-duck took a break and displayed with his female, then he went back to the shoveler, grabbed it again by the neck and proceeded to beat it another 15-20 times. By now the shoveler was looking pretty limp (though still alive). It was pecked at and released and both steamer-ducks displayed together again, and the male steamer-duck now began to move away from the shoveler. The shoveler now began to move (slowly) toward the shore and eventually got there. Then it died. ‘Examination of the specimen disclosed several broken bones, hemorrhages in the lower neck region and massive internal bleeding at the base of the right leg’ (p. 89). During the course of their study at Laguna de la Nevada, Santa Cruz Province, Argentina, Nuechterlein & Storer (1985a) picked up the carcasses of six ducks that had definitely been killed by steamer-ducks within a single week. Why steamer-ducks are so aggressive remains the source of debate (Murray 1985, Livezey & Humphrey 1985a, b, Nuechterlein & Storer 1985b). But don’t mess with them.

Refs – -

Corbin, K. W., Livezey, B. C. & Humphrey, P. S. 1988. Genetic differentiation among steamer-ducks (Anatidae: Tachyeres): an electrophoretic analysis. The Condor 90, 773-781.

Humphrey, P. S. & Livezey, B. C. 1982. Flightlessness in flying steamer-ducks. The Auk 99, 368-372.

Livezey, B. C. & Humphrey, P. S. 1985a. Territoriality and interspecific aggression in steamer-ducks. The Condor 87, 154-157.

- . & Humphrey, P. S. 1985b. Interspecific aggression in steamer-ducks. The Condor 87, 567-568.

- . & Humphrey, P. S. 1986. Flightlessness in steamer-ducks (Anatidae: Tachyeres): its morphological bases and probable evolution. Evolution 40, 540-558.

Murray, B. G. 1985. Interspecific aggression in steamer-ducks. The Condor 87, 567.

Nuechterlein, G. L. & Storer, R. W. 1985a. Aggressive behavior and interspecific killing by Flying steamer-ducks in Argentina. The Condor 87, 87-91.

- . & Storer, R. W. 1985b. Interspecific aggression in steamer-ducks. The Condor 87, 568.

Comments

#1 Jorge Velez-Juarbe
December 15, 2008

I have always though of geese as been vicious (I was “attacked” when I was a kid), but not ducks!! I wonder if these ducks are as fierce when facing a predator? Or are they only bullies with other birds? Will the population in the Falklands be more prone to have a higher number of flightless individuals? With the Warrah (Dusicyon australis) extinct, there are no other mammalian predators to fly away from, right?
#2 Neil
December 15, 2008

Yikes I had no idea they were that aggresive. It would be interesting to see what would happen if one met a mute swan. Mute swans are the only thing that can chase of a canada goose* on my local lake, and with cases of swans drowning dogs, I wonder how a steamer duck would cope?

* except a territorial coot – now an agile coot talons up against a steamer duck would be interesting….lol
#3 Art
December 15, 2008

I wonder if these ducks might help rid certain areas of excessive numbers of muscovy ducks that are making a nuisance of themselves by destroying plantings and fouling large areas.
#4 Angela
December 15, 2008

I was really surprised to hear that we used to have a flightless “diving goose” on the west coast of California that only went extinct in the Holocene. I’m a salmon ecologist and naturalist, but had never heard this until last year. Go here, here and here.

Well, sort of a tangent, but this post immediately brought it to mind. Those steamer ducks must be steamed about something! yuk yuk ;p
#5 Dartian
December 16, 2008

Jorge:

With the Warrah (Dusicyon australis) extinct, there are no other mammalian predators to fly away from, right?

Even with the warrah gone, steamer duck are not safe from mammalian predators. Both killer whales and sea lions have been recorded to kill steamer ducks (Straneck et al., 1983).

Reference:

Straneck, R., Livezey, B.C. & Humphrey, P.S. 1983. Predation on steamer-ducks by killer whale. Condor 85, 255-256.
#6 Dartian
December 16, 2008

Regarding the question why steamer ducks are so aggressive: I suggest this should be seen in a phylogenetic context. Yes, steamer ducks are aggressive, but so are many other anatids*. The steamer ducks are probably most closely related to the shelducks and sheldgeese, among which there are many highly pugnacious species. And swans and geese, as well known, are quite aggressive too.

* In Johnsgard’s (1965) opinion, the “most dangerous of all waterfowl” is the African spur-winged goose Plectropterus gambensis.

If anything, it’s the ‘true’ ducks that are exceptional in being relatively unaggressive. At least for those of us who live in the Northern Hemisphere, dabbling and diving ducks tend to be the anatids we’re most familiar with. Thus, we may have a slightly distorted idea of how aggressive waterfowl ‘should’ be.

Reference:

Johnsgard, P.A. 1965. Handbook of Waterfowl Behavior. Cornell University Press, Ithaca.
#7 Jerzy
December 17, 2008

European ducks, geese and swans do fight heavily, and fight to death. In the breeding season, it is male duty to chase every other waterbird off a patch of waterside vegetation which feeds his female and chicks. Just watch your local ducks or swans carefully.

BTW – flying/flightless brings to my mind a theory, that bird feathers evolved mainly for display, but unintentional effect was that juveniles became volant. Juveniles of bird ancestors reached adult size over several years (not weeks or months like modern birds). In such situation, it is difficult NOT to have an evolutionary intermediate link with flying juvenile and flightless adult.
#8 Dartian
December 17, 2008

European ducks, geese and swans do fight heavily, and fight to death. In the breeding season, it is male duty to chase every other waterbird off a patch of waterside vegetation which feeds his female and chicks. Just watch your local ducks or swans carefully.

Sorry, Jerzy, but I have to disagree with you regarding the ducks. Perhaps I wasn’t clear enough in my earlier comment: what I wanted to say was that it is the relative lack of inter-, not intraspecific, aggression that differentiates ‘true’ ducks from swans, geese and steamer ducks. Male ducks* may fight amongst eachother during breeding season, but they do not chase other species away when the female is incubating. In fact, male ducks don’t take any part in rearing the young, period; after having mated with the female, they’re gone. They don’t hang around to defend territories and therefore they don’t need to be particularly aggressive either.

* Meaning species belonging to Anatinae, Aythyinae and Merginae. The shelducks, Tadorninae, are a different story; they are more goose-like.

Geese and swans, in contrast, mate for life. Their males defend territories, even against other species.
#9 Terry Hunt
December 17, 2008

Apologies if this is a silly question, but how do we know that T. patachonicus is not actually in the process of regaining flight, having previously been entirely flightless like the other Tachyeres species?

(I realise the 5th reference listed above would probably tell me, but I can’t readily access it.)
#10 Carlos
December 18, 2008

Terry Hunt:

“Apologies if this is a silly question, but how do we know that T. patachonicus is not actually in the process of regaining flight, having previously been entirely flightless like the other Tachyeres species?”

Well, it has been suggested that some bird groups have redeveloped flight (tinamous, being the crown group of the ratite clade, are an example, and “non-avian” maniraptors might very well have lost and gained flight multiple times), but its usually assumed that they retained flight while their flightless relatives had lost it independently.

Plus, this specie of steamer duck is the most basal of the genus, so…
#11 Jerzy
December 18, 2008

I am no expert in ducks, but I saw male Mallard keeping company to female and chicks and chasing other ducks away from food.
#12 David Marjanovi?
December 18, 2008

tinamous, being the crown group of the ratite clade

NO!

Here’s the definition: The crown-group of a clade is the most recent common ancestor of all extant members of a clade, plus all its descendants. It follows logically that all extant palaeognaths are crown-group palaeognaths.

BTW: one species. It’s one of the Latin words that’s identical in singular and plural.
#13 Rose
December 19, 2008

Yes, ducks are great.

Mallards, in particular, have splendid orange legs (it’s the carotenoids you know).

A very successful and fascinating bird.
#14 Terry Hunt
December 19, 2008

In answer to my query Carlos wrote:
“Well, it has been suggested that some bird groups have redeveloped flight . . . , but its usually assumed that they retained flight while their flightless relatives had lost it independently.

Plus, this specie of steamer duck is the most basal of the genus, so…”

I’m suspicious of assumptions. Let me expand a little.

Since all four (known, extant) Tachyeres species presumably ultimately descend from a flighted ancestor, and if T. patachonicus is still in the process of losing flight, then to account for the other three flightless species there must have been at least one other independent loss, and possibly two or three (depending on how T. pteneres, T. leucocephalus and T. brachypterus are interrelated). If we call the losing or regaining of flight X, then in this case X = 1.5-3.5.

It would be equally if not more parsimonious to assume that a more recent but still common ancestor of all four species had lost flight, and that T. patachonicus has partially regained it. In this case X = 1.5.

If the four Tachyeres species were widely distributed, this would seem logistically unlikely, but they are, I gather, restricted within a relatively small area, around the coasts of the southern end of South America plus some nearby islands (of recent dispute), over which they could surely have spread entirely by paddling.

That only the (sometimes) flighted T. patachonicus is found, still within this range but away from the coast on freshwater lakes, to which it alone of the Tachyeres can fly, may weakly support my ‘flight being regained’ conjecture. If the ancestral Tachyeres (more basal than T. patachonicus) was flighted, one might expect that T. patachonicus would have had time to become more widely distributed, whereas if its partial flying ability has only recently started to emerge, its restriction to the regions proximate to its flightless cousins is understandable.

I would also predict that if the ur-Tachyeres were flighted, then fossils (if any were known) might indicate an original genus range greater than today’s, whereas if it were flightless they might only be found near a ‘radiative core’ within the current range.

On a slightly different tack, if any of the flightless steamer ducks could be domesticated (obviously the agression would be a problem, but at least they could be kept without any need for wing-clipping, and the Magellanic T. pteneres looks to have plenty of meat on it), I wonder how easy it would be to artificially select them so as to produce a breed of, ahem, Flying flightless steamer duck?
#15 pete saussy
January 23, 2010

never would have guessed wkhy they are called steamer ducks. most excellent creatures. reminds me that german submarines preferred making surface attacks to submerged. wonder what led them to attack submerged?