Which one is the top prey hunted by the Apex Predator's?

[Brehm]

@sanjay: Hmmm, well, i think we can keep Hippo's and Giraffe's, but just barely

About hippo's, i have a slightly different opinion. I agree that hippo's are close to unvulnerability in water or very close to water, but once their place in their water hole become's sparse in hot days and they are forced to walk a bit further due to those circumstances, it look's like they fell prey to lion's rather easily. Throughout the whole year, i find the "black death" more difficult to take on, while it depend's more on the season for hippo's.

At the moment, i also slightly tend to walrus like Pckts. Till we analyze other's a bit more

Some information about Walrus - polar bear relationship:

From "Interactions between Polar Bears and Overwintering Walruses in the Central Canadian High Arctic" by Wendy Calvert and Ian Stirling.

I found this while looking for information about walrus - ice bar interaction, the first site where i found this article was the "shaggygod" board.

Some interesting quotes from the article:

"Abstract:There are few records of predation by polar bears( Ursusm aritimus) on walruses( Odobenusr osmarus), a though their distributions overlap extensively. During
the late winter and early spring from 1981 through 1989, we recorded interactions between polar bears and walruses in the central Canadian High Arctic, where walrus
movements are severely restricted in the winter by limited areas of open water for breathing and haulout holes. Predatory behaviour of bears and anti-predator behaviour
of walruses were observed. We found evidence that polar bears made wounding but non-fatal attacks on 3 walruses, killed 3 walruses, and probably killed 4 others. One
walrus was frozen out of its breathing hole and vulnerable to predation. Although the vulnerability of walruses to polar bear predation would vary with habitats and seasons,
it is clear that polar bears are important predators of walruses in the central Canadian High Arctic in late winter-early spring"

The time of observation is already 2 decade's in the past, but still representative. Today there are luckily some short clip's showing ice bear's predating and killing adult walruses, even though this is of course not an indicator for higher frequency.

"Polar bears are powerful predators, capable of taking large prey such as bearded seals (Erignathus barbatus) (Stirlinga ndA rchibald1 977) and belugas( Delphinapterus leucas) (Lowry et al. 1987), but walruses are the largest of the polar bear's possible prey, and they are able to use their tusks for defence. Loughrey (1959) felt there was little doubt polar bears prey on calves and subadults, but found factual accounts scarce. Fay (1982) stated that he knew of no confirmed records of predation by bears on walruses. He concluded that contact between polar bears and walruses occurred mainly in summer and that only younger walruses are really vulnerable to predation. Although Fay (1985) listed predation by polar bears as 1 of 3 primary causes of mortality among walrus calves (along with predation by killer whales [Orcinus orca] and crushing), he noted that Mansfield (1958) has calculated that total mortality of walrus calves is low compared to otherpinnipeds. It is hard to assess if this predation would be significant to the population."

"Females and calves usually hauled out in groups of 4 or more, were more vigilant than all-male groups, and were easily disturbed. We sometimes saw them rush into the water even when we could see no cause for the disturbance. In groups of females and young, the calves were as near, or nearer, the water than the adults. Although calves often slept, the females remained alert. In contrast, adult male walruses were much less easily disturbed when hauled out and more reluctant to enter the water. People or bears could often approach to within a few metres. When approached closely, large male walruses often backed into the water slowly, ready to fight with their tusks if necessary. Bears are able to use rough ice for cover to get close to a walrus before charging, which could be particularly dangerous to subadult animals that are less capable of fending off a bear. Smaller walruses hauled up alone often entered the water head-first shortly after a human, or in some observed instances, a bear, was detected. If several male walruses were hauled out together, the largest males tended to lie furthest from the hole, with the subadults nearest. The subadults were more restless and possibly more observant of predators. The combination of being watchful and nearest the water probably increased their chances of escaping safely from a charging bear that must first face the tusks of the larger male walruses."

"Between 1981 and 1989, we found evidence of 10 walruses that we believe were wounded or killed by polar bears (Fig. 1). The date of death is known only for the kill at site 2 where the bear was observed killing a large adult male walrus and pulling it from its haulout hole (D. Grant, pers. commun.). All the other carcasses were frozen and partially eaten when found. Wind-blown snow often obscured the bear tracks in the area, making it difficult to reconstruct the attack, but the presence of bear claw marks, blood smears, and scratching marks made by walrusf lippersi ndicateda n interactionh ad occurred. In 2 cases, the haulout hole near the carcass was still unfrozen, suggesting the walruses were killed on the ice before they could escape, and that freezing-out was not a factor. There was blood soaked into the snow beneath the head of the adult male found dead in February 1987 at the shoreline tidal cracks below our camp (site 11), suggesting that a bear killed him, though possibly only after the ice shifted and he was frozen out. At 6 of 7 sites of kills or probable kills, polar bears were feeding on the carcass when it was sighted, but we did not know if they were predators or scavengers."

"Although walruses hit each other on the neck and shoulder with their tusks when fighting, they are protected by a thick skin. Most wounds are superficial and bleeding is limited".[/i]

"Although encounter and predation rates likely vary among different habitats, we suggest that polar bears are important predators of walruses in our study area. The data also suggest that subadult walruses are most vulnerable, but that large male bears are capable of also killing adult male walruses. Polar bears may also kill more walruses in pack ice situations than has been reported previously." 

According to this, it can be concluded that bulls become extremely rarely victims to ice bear's, for good reason.

Full article:         http://www.bearbiology.com/fileadmin/tpl...ling_8.pdf

Some clips about polar bear - walrus interaction:

The hunt went horribly wrong for this bear, after the mother of the calf hit him with her tusks. A demonstration, how devastating a single hit from walrus tusks can be!

A polar bear with his walrus kill, after a blood bath.

Good example showing the effectiveness in defence of walruses blubber. It looked like the bear had almost all times of the world in killing the walrus.

Walruses are not only prey, but also competitor's over food to polar bear's.
Enemies: Most bears have few natural enemies except for humans and the human impact on bear habitat.  An exception to this is threat walruses pose to polar bears.  Polar bears and adult walruses are rivals, occasionally coming into contact while feeding on whale carcasses or in the process of killing seals. On land, a polar bear has the edge over a walrus, but once in the water, the walrus has the edge. It can grab the polar bear from below, stab the bear with its tusks, and repeat this resulting in serious if not fatal injury to the bear (Brown 1993, p 108-109).

From: http://www.bear.org/website/bear-pages/p...facts.html

That surprised me, till i saw one encounter over food in a highly recommended documentary yesterday: "Heavyweights with unexpected skills" - a walrus documentary with deep insights about this strange looking creatures.

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