[CliffordK (OP)]

Has there ever been a stable ice bridge between the Antarctic Peninsula and Argentina?

I can't seem to find any information on the web relating to such a formation.  It just seems to be possible during a glacial maximum. 

However, several animal species never seem to have migrated to Antarctica including Bears, Foxes, Wolves, or various Cats. 

I.E.  Penguins and Bears would not be a good mix.

[graham.d]

When I first looked at the question I thought you were referring to continental drift and, therefore, further back in time. They were part of one supercontinent (Gondwana) at one time, but we are going back several hundred Million years and it wasn't a cold place then. I guess you are referring to recent times, geologically speaking. As you say, there are no bears, foxes, wolves or cats in Antarctica now - in fact there's nothing big that isn't aquatic.

I would guess that it takes a long time to establish an adapted species capable of surviving, so a temporary connection, especially one that only forms during really cold periods, would not be conducive to a species migrating somewhere even colder then finding a way to survive and prosper; all the factors would be against them. The situation is not the same in arctic regions where there migration can be gradual and where there is time for species to adapt over a long period.

[CliffordK (OP)]

Thanks,

So penguins are migratory birds.  And, while a land predator might enjoy bountiful summer hunting on Antarctica, if there was an ice bridge to Antarctica, say 20,000 years ago, the migration would have had to be essentially an anti-migration, heading south into a barren landscape mid-winter while all the prey had already migrated northward for the winter, and then waiting for the prey to arrive later in the summer.

Yet, one could imagine a predator could venture out onto the ice in the winter and get stranded on the shrinking summer sea-ice, and then be driven southward onto Antarctica.

Theories indicate that Antarctica had several periods in history in which it had relatively ice-free summers, each lasting in excess of 50 million years.  If there were any land mammals that would have found the continent during the warm periods, none have survived until today.

[graham.d]

If you go back in time then there were larger animals on what is now the antarctic. 50 million years ago I think antarctic was still connected with Australia and the whole region was quite temperate (Eocene period). I guess, in theory, these animals could have been isolated when the continents drifted apart and subsequently adapted to the cooling climate. However, the environment is harsh and unrelenting and, without land-based vegetation at the bottom of the food chain, life for larger predators may not be sustainable. The need would be to predate, ultimately, on sea creatures so they would have to be capable of catching them. Such ability would also enable them to seek an easier life :-)

[Don_1]

....... without land-based vegetation at the bottom of the food chain, life for larger predators may not be sustainable. The need would be to predate, ultimately, on sea creatures so they would have to be capable of catching them. Such ability would also enable them to seek an easier life :-)

I think you have hit the nail on the head here. Today, inland survival of any animal would need to be dependent on the annual visitation of Emperor Penguins. Though they may be plentiful in numbers, they are only inland for around 4 months (including the trek from and back to the sea). Any animal dependent on the penguin's breeding season would need to survive 8 months or more without a food source. This would require an enormous capability to store fat, making the animal so heavy, it would probably be better off at the coastal regions. Here it could get some relief from carrying such weight by dipping in the sea, which brings us back to graham's scenario.

[imatfaal]

Do we know much about Ocean Currents back in the previous glacial maxima; but it would seem to me that any serious landbridge would disrupt higher and surface currents to a huge degree.  The globe would cease to have a viable circumferential route apart from very deep water

[graham.d]

Matthew, Clifford was speaking of an ice bridge rather than a land bridge. In the last Glacial maximum the distance was probably not so far as to imagine this as being impossible given the extent of the ice in S. America and the much lower sea level, meaning that Antarctica was therefore much larger.

http://en.wikipedia.org/wiki/Last_Glacial_Maximum

[imatfaal]

Yep,t hanks G.d - I was not reading carefully enough.