I have some pictures of some ducks I took at Bracken Ridge (Brisbane North) Qld
I couldn't seem to identify them, are any of them native or are they all ferral?
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All are domestic Mallard varieties.
Thanks Zosterops, not what I want to hear but at least now I know
Hi Devster,
I think some of them are possibly hydbrids between the Northen Mallard (which is, as Zosterops said, introduced) and the (native) Pacific Black Duck, which is perfectly possible, as they're both types of Mallard.
True, the last pic especially shows birds with signs suggestive of PBD-influenced facial masks.
They are both members of the Anas genus, being both 'Mallards' is subjective depending on your species definition, unless you consider all Anas species as Mallards (then equally a Shoveler could be considered a Mallard, imo it's best to differentiate if simply for clarity's sake at least in general conversation).
The members of the group are however indeed very closely related and can freely interbreed usually with fertile offspring, a fact both resulting in the perceived genetic pollution of various wild Anas species where they come into contact with introduced Mallards* e.g. in New Zealand they're all but lost their subspecies of PBD through hybridisation, as well as directly challenging the conventional species concept.
*Though many other Anas species naturally hybridise with Mallards (A. platyrhynchos) even where the various species exist naturally.
Interestingly the now extinct Mariana Mallard from the Mariana Is. was believed to be a hybrid of Pacific Black Duck x Mallard which formed its own species, perhaps we've inadvertently gone some way to 'recreating' it.
http://en.wikipedia.org/wiki/Mariana_mallard
Wow, I did't realise that the relationship between the two species was that complex. Thanks for clarifying that they do produce fertile hybrids Zosterops. Most of the ducks don't look like a F1 hybrid to me (have too indistinct facial bands), and I was wondering if maybe I was wrong with my PBD suggestion.
I think all the ducks in the photos have some PBD in them, except possibly the middle duck in the sun in photo 4.
Many waterfowl can produce a crazy wide crosses and many are fertile.
I reckon the one on the right in the last pic is an F2 Mallard x PBD x PBD, it appears to have more pronounced facial markings.
It can be extremely difficult after several generations of hybridisation with PBDs x Mallards to distinguish hybrid from pure species (remember that these hybrids are still fertile after many generations, the NZ birds must be many generations interbred and may even evolve into a new species ala the Mariana Mallard??).
The presence of orange legs was once used to signify PBD/Mallard hybrid status, though I've heard it suggested that some pure PBDs in breeding condition can also display this characteristic and it has been claimed that some purported hybrids were mistakenly culled.
Maybe 20% of all seemingly pure PBDs in Aust have some Mallard genes already and you wouldn't even know without DNA analysis.
A lot of the Aust mainland stock do appear to be a lot purer PBD when compared to a typical NZ PBD example which are clearly hybrid swarms, though the higher Mallard presence there will reflect in the phenotype. Maybe our hybrids will be subsumed into the large mainland Aust. PBD population which will serve as something of a buffer.
Across the Tasman they have a lot more wild-type Mallards (banded NZ Mallards have reached Aust as vagrants and there has been some natural gene flow back and forth between Aus/NZ PBD stock- now presumably involving Mallards, and Mallard/PBD hybrids interbreeding with our stock. Note the NZ birds are a different subspecies called Grey Duck), whereas most of the Mallards in Aust from what I've seen are clearly a mix of domestic varieties which is reflected in various bizarre hybrids with PBDs. However in Tasmania I saw more hybrids than pure PBDs (maybe some come from NZ???).
One issue I've heard is that Mallards are adapted to permanent water bodies in the Northern Hemisphere and as such may impart undesirable sedentary genes into the PBDs which are evolved to be nomadic in Australia's drought-prone climate, though crossing the Tasman may well suggest otherwise??
The Mariana birds were interesting on two fronts, firstly if they were indeed PBD/Mallard hybrids (unfortunately we can't go back and study them) this presumably represents natural colonisation events as vagrants to Mariana from the northern and southern hemisphere species and so maybe it's conceivable that Mallards would have reached NZ and maybe even eventually Aust on their own accord (maybe vagrants have already reached NZ you wouldn't even know, look how many amazing vagrants show up in Aust every year). The new Mariana 'species' would have to have been one of the species which existed over the shortest time period ever, hybridising and evolving in a few tens of thousand years, then falling to the predictable hands of hunting and wetland drainage. The new NZ birds have been called 'grallard'. I read the NZ Mallard population is estimated at 4.5 million (!!), not including hybrids.
Also intriguingly the Mariana birds were supposedly either 'PBD morph' or 'Mallard morph' in morphology yet the same 'species', whereas from what I've seen the hybrids in Aust and NZ tend to display intermediate characteristics between the two species.
For more info on Mallard hybrids:
http://10000birds.com/hybrid-mallards.htm
Key for PBD identification
http://ebird.org/content/newzealand/news/grey_ducks/
What an interesting discussion! It complements what I'm reading in Tim Low's Where Song Began.