Once again, no. The Emperors are *only *there in Winter. So areas with Emperors will have no penguins in summer (Emperor and other penguin colonies don’t really overlap).
Meanwhile, the breeding season for the other penguins is in Summer, but a lot shorter. So they’re not there the *whole *Summer, and they are at sea pretty much entirely for the rest of the year. So there will be several months without *any *land-based prey.
Despite what you may have seen on documentaries, which are heavily skewed to documenting their breeding seasons, Antarctic penguins are otherwise almost entirely marine, don’t mostly hang around under the pack ice blowholes (because that’s where seals hang out), but rather migrate quite a distance out to feed, and so don’t behave the way the most common polar bear preys do.
Having said that, there are many seal species in Antarctica that behave the same way Arctic seals do, so given sufficient time and numbers, I think polar bears could adapt. Certainly the Antarctic seals would not be prepared for an ambush blowhole predator.
But in a scenario where polar bears are set next to an Emperor colony? They’d have one season of glut, then be forced to wander off after the Emperors leave. If they’re lucky, they’ll follow them to the shore and switch to seals until the summer penguins arrive. If not - well, it’s a big, barren continent, they’re definitely dead…
The population of all species is probably much more than that, even just considering Antarctica. Two species, the small Adelie and the Emperor breed in Antarctica proper (not including the Antarctic Peninsula). The population of Adelie is believed to be about 7.5 million (some sources say 4.5 million pairs, so over 9 million). The population of Emperor is estimated at around 600,000. Another four or so species breed on the Antarctic Peninsula, the most numerous being the Chinstrap with a population of 8 million (although estimates vary).
Yes, but the breeding seasons of different species are offset, so there are almost always penguins breeding in Antarctica sometime during the year. The Emperor, as is well known, breeds in the middle of the Antarctic winter. Adelies and others breed during the Antarctic summer. There might be short gaps between breeding seasons but polar bears could probably make it through either by fasting or eating seals or fish.
In particular, conditions on the Antarctic Peninsula aren’t that different from their Arctic range. Temperatures are warmer, and there is a greater variety of possible food species. I think it’s likely a population of polar bears could survive on the Peninsula indefinitely.
If the cycles are triggered by day length, I think they would adjust pretty quickly to the Antarctic seasons. On the other hand, they could be triggered by food supply in which case it doesn’t matter what season they happen.
Polar bears have a relatively slow rate of population increase. Females start to reproduce at five years, usually have two young, and survival rate of young isn’t that large.
Polar bears no doubt would be highly disruptive locally. The greatest threat would be to Emperor Penguins, which have the lowest population and are concentrated in large colonies. However, it would probably take centuries for a handful of polar bears to increase in population enough to cause their extinction. Other, smaller species of penguins could probably survive indefinitely.
You have emperors in winter, along with simply moving to the edge of pack ice where there are seals and fish. You have other penguins at other times of the year. Bears don’t necessarily eat every day.
Let me put it this way - I can’t put my finger on why they would NOT survive in such an environment. I’d prefer no one try transplanting bears down there to find out because they’d wreck unholy disaster on the seabird colonies that never had to deal with a land predator before even if eventually all those bears do die out.
During that short gap they also need to move from inland breeding colonies to coastal ones, and vice-versa later , when they could be as much as 120km distance apart. While fasting, because that’s shelf ice, not sea ice they’ll be crossing, so no seal blowholes on the way.
You’re proposing a seasonal glut at one colony and then another (which probably won’t recover regular assaults like that in breeding season, or just won’t return - see the way the Halley Bay colony’s adults have just abandoned it after 2016’s chick die-off) So maybe they can play that game for a few years. A decade at best? But ultimately, it won’t be sustainable. Antarctic penguins just aren’t ready for a land-based predator.
The South Shetland islands are 120 kilometres (75 mi) from Antartica.
They can swim much further than that:Just how far can a polar bear swim? Polar bears (Ursus maritimus) are capable of swimming incredible distances, according to a new study published in Zoology, which recorded polar bears regularly swimming over 30 miles (48 kilometers) and, in one case, as far as 220 miles (354 kilometers). The researchers believe the ability of polar bears to tackle such long-distance swims may help them survive as seasonal sea ice vanishes due to climate change.
Emperor Penguins begin arriving at their breeding colonies in March, and the last young fledge in December or even January. The breeding season of Adelies runs from October to February. So there are penguins ashore almost the entire year. While it’s true that Emperors and Adelies don’t breed in the same place, Polar Bears are capable of moving huge distances to forage. There are certainly some areas, especially around the Ross Sea, where Polar Bears could survive by shuttling between Emperor and Adelie colonies seasonally.
My gut feel is that the Antarctic seals and fish are not the same as the Arctic seals and fish, and the behavioural differences will catch the bears out and they won’t adapt in time. Feeding off penguins would be just a temporary stopgap, not a permanent ecological niche.
Plus I’m sure they’ll try their “I’m a marine mammal, really” shtick, and meet packs of black-and-white death. I’m aware their Arctic range overlaps with orcas, but the Southern Ocean is a different environment, IMO.
That’s pretty routine for Polar Bears. They are adapted to endure months of fasting at a time. They may have home ranges of 350,000 sq. km or more. No big deal.
It depends on how much switching they can do to seals and other marine mammals. As I said, the most vulnerable species would be Emperors. There are some colonies in parts of Antarctica not inhabited by Adelies or other penguins. Unless bears were able to survive on seals when the Emperors were at sea, those colonies might survive. Smaller species of penguins might be able to adapt. After all, there are enormous numbers of ground-nesting birds with vulnerable young that are able to breed and survive in the Arctic despite the presence of Polar Bears and Arctic Foxes.
I don’t think the major impact of polar bears would be to adult penguins, the big blow would be to the eggs. Polar bears would quickly figure out that strolling through the nesting area nomming the eggs and chicks is way less hassle than chasing around after the adult birds and even a few polar bears could easily devastate an entire year’s worth of chicks and eggs in short order. Penguins can move around or jump in the ocean to avoid bears, the eggs and chicks are stuck at the buffet.
I suspect if some polar bears were released into Antarctica a few would starve to death wandering inland not realizing all the food would be by the coast. The interior of continent is barren and it would be very easy for **humans **to get lost and either freeze or starve to death. So I doubt polar bears that were released there would fair much better.
In the Arctic polar bears find most of their food on the coast or on the ice. There is no reason to think they would wander inland. They don’t wander onto the ice caps on Greenland or Baffin Island.
Polar bears aren’t humans, and of course not even humans would wander inland from the coast in Antarctica unless they were looking for the South Pole. Polar bears are a lot better adapted to the climate than tropical savanna ground apes.
