[rpharvey]

I took this picture at a natural looking zoo in Christchurch and always assumed the two Black Swans were captives. I recently read some articles about Black Swans and now I wonder...

Most animals in the area were identified by signs (including the eels the caretaker is feeding). The swans were not. And many other ducks and smaller birds were flying in and out of the pond area. I never saw the swans fly but wonder if that was just because they have it made sitting right where they are...

Any opinions on whether or not these guys were most likely captives, or might they have been wild birds just hanging out at the animal park where there was plenty of easy food.

https://picasaweb.google.com/harveyr...94041744484146

[Marmot]

Did they look as if they had their wings clipped at all to make them captive.

Looking at Opus it states they have been introduced to all of New Zealand.
http://www.birdforum.net/opus/Black_Swan

[Mysticete]

My impression was that Black Swan was a natural colonizer from Australia

[MJB]

Originally Posted by rpharvey

I took this picture at a natural looking zoo in Christchurch and always assumed the two Black Swans were captives. I recently read some articles about Black Swans and now I wonder...

Any opinions on whether or not these guys were most likely captives, or might they have been wild birds just hanging out at the animal park where there was plenty of easy food.

I think I'm right in saying that the Black Swan was introduced to New Zealand in the 19th century as an ornamental waterfowl, but they adapted so well that they became a serious competitor near waterbodies to sheep, then the main industry, especially in South Island. An extirpation programme was undertaken (bounties may even have been paid) and the population collapsed. Some of our Kiwi contributors can probably advise if the bird was completely eliminated. However, some time in the 20th century, it is thought that natural colonisation occurred, and the population slowly began to grow again.

Quite how the population is viewed nowadays I am uncertain, but I saw quite a few birds in 2004 when I was last in NZ.
MJB

[Chlidonias]

the two black swans at Willowbank (where the photo was taken) are part of the zoo's collection not wild birds, but black swans are very very common in the wild all over NZ. They were introduced in the mid 19th century from Australia. After the Wahine storm in 1968 the population collapsed to some degree but recovered well afterwards. There has (probably) been some natural colonisation from Australia (eg the introduced population is considered to have increased more substantially than would have been possible if there hadn't been some natural trans-Tasman spread as well).

The subfossil record of swans in NZ (formerly treated as a distinct endemic species, Cygnus sumnerensis) is now considered to be from a natural pre-human population of Australian black swans.