Endemic NZ Swan

Discussion about the evolution, relationships, and naming of New Zealand birds
Ian Southey
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Endemic NZ Swan

Postby Ian Southey » Fri Jul 28, 2017 5:01 pm

Following a piece on the radio I found this paper which says we had an endemic swan which was exterminated by Maori https://assets.documentcloud.org/docume ... reveal.pdf

A bit surprising because it doesn't seem that long ago that some effort was made show that New Zealand and Australian swans did not differ in size or shape.

Ian
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Charlotte
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Re: Endemic NZ Swan

Postby Charlotte » Sat Jul 29, 2017 3:38 pm

There was a write up in Stuff about this as well.
New Zealand's black swans are not native, they're imports from Australia, new research finds.
http://www.stuff.co.nz/environment/9511 ... d=app-iPad
andrewcrossland
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Re: Endemic NZ Swan

Postby andrewcrossland » Sat Aug 05, 2017 10:09 pm

Maybe someone should explain to the folks behind this story that even if we go back to believing that the extinct swan was Not black Swan, the fact remains that black swans colonised nz in the mid-late 1800s and are therefore natives. Sounds like someone behind this news story needs the difference between native and endemic explained to them?
Jim_j
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Re: Endemic NZ Swan

Postby Jim_j » Sun Aug 06, 2017 1:16 pm

I must admit I had always thought they were deliberately introduced - I see the Birds on-line (and other references) state that 100 birds were bought over from Melbourne but that it is "believed" they also self introduced because there seemed to be a larger increase in population than expected.
A bit vague really and I'm always a bit wary of coincidences.

It sounds more to me that someone suggested this as a theory and it has become established fact
Anyone seen anymore info that would support this - some definitive numbers perhaps?
Were birds sighted in NZ prior the deliberate introduction? - What was the actual speed of increase?

cheers
jim
andrewcrossland
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Re: Endemic NZ Swan

Postby andrewcrossland » Sun Aug 06, 2017 1:41 pm

I think the reverse theory ( that black Swan established it's large pop from human introduction ) was actually the theory that became established fact. The nos of black Swan introduced were much smaller than 100. I do have precise nos somewhere but not at hand, however on the Avon river in chch it was something like 14 birds. Within a short number of years there were hundreds in canty and the west coast the old introduction myth was just a legacy of 1930's-70's nz ornithological false truisms.
Jim_j
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Re: Endemic NZ Swan

Postby Jim_j » Sun Aug 06, 2017 1:53 pm

ok cheers Andrew.
I got the 100 fro Te Ara NZ encyclopedia on line.
See below

"Native or introduced?
About 100 black swans were brought to the South Island from Australia in the 1860s, and the species has traditionally been regarded as introduced. However, numbers increased faster than expected, suggesting more birds arrived independently – in which case it should be considered a self-introduced native."
Jim_j
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Re: Endemic NZ Swan

Postby Jim_j » Sun Aug 06, 2017 7:50 pm

Although thinking about it a bit more - the fact it has been established that the "original" NZ Black swan was measurably different from the current model - doesn't that imply there was little or no movement from Australia.
Its east to see how other recent Oz immigrants exploiting the changes to the environment european settlement brought - but I would have thought the habitat for swans was largely similar?

cheers
jim
Alan Tennyson
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Re: Endemic NZ Swan

Postby Alan Tennyson » Sun Aug 06, 2017 11:12 pm

Here's a brief article that I wrote about the extinct swan:

http://blog.tepapa.govt.nz/2017/07/26/a ... oric-swan/

In 1890, the Canterbury Museum’s Director, Henry Ogg Forbes, described the prehistoric species Cygnus sumnerensis based on fossil bones but by 1998 it was considered to be the same as the black swan. DNA analysis has allowed us to re-examine this question and show that Forbes was right (& examination of a larger number of skeletons shows that there are, in fact, significant morphological differences between these species too).

Technically the black swan should be considered 'native' but I consider it, like pukeko & swallows, to be a 'native invader' that only established in the country due to human modification of the environment. We don't know enough about the extinct species yet to understand how it might have differed from the black swan.
Ian Southey
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Re: Endemic NZ Swan

Postby Ian Southey » Mon Aug 07, 2017 6:31 am

I can't agree with the designation of Black Swans as anything other than an introduced species. I am not aware of any records prior to the recorded release of the large quantity of birds mentioned already. I think there are two reasons why people might think this.

The first is that they breed well and can raise young at any time of the year. This last weekend I saw eggs and large downy chicks and that's the middle of winter. I think these birds simply dispersed widely, perhaps more than some early introductions, and bred successfully but this is not unusual for birds and mammals introduced at that time.

The other reason is that they were large enough to be seen, familiar enough to be recognised but a novelty for people used to white swans so gossip worthy at the time.

As a nomadic Australian wetland bird there is a high likelihood that would arrive on their own and could breed here but unless someone sees one with an Australian band standing on a nest we will never know ... and they would still be introduced birds.

Ian
Jim_j
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Re: Endemic NZ Swan

Postby Jim_j » Mon Aug 07, 2017 3:05 pm

Alan - wouldn't you consider the black swan a little different from those other species?

I would have thought the wetland habitat that they occupied in the mid 1800's (whether self-introduced or not) was not that much different from the "previous" black swans habitat - and as such the birds were just filling a 'temporary" empty niche actually caused by previous human interference (over-hunting).
I realize that even small changes to the environment can give a species an advantage - but the fact that there was a black swan here (endemic/self introduced or both!) in pre-european times indicates that the pre-human environment was suitable for this sort of species.
I guess it's also possible that previous self-introductions (in pre-european times) didn't establish due to the on-going hunting pressure

cheers
jim

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