Mammalian conflict

[creature386]

This one was epic:


More on Wolf vs Moose:

[elosha11]

Great polar bear v. walrus encounter Supercommunist. I've seen some other such conflicts on youtube, but not this particular one. The evidence seems fairly clear that polar bears would be the winners a majority of the time in this conflict, if the bear is strong enough to get the walrus up on land and away from the herd.

[creature386]

[Supercommunist]

erwinniemand.wordpress.com/2012/11/09/jackal-kill-bat-eared-fox/

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Okay, so I know we have a general animal conflict thread, as well as threads devoted specifically to avian conflict and fish conflict. However, I also understand that the first of these three has a ton of posts, is disorganized, and my browser has even crashed a few times from the sheer amount of stuff in that thread. In order to mitigate this issue, I am going to encourage separate threads for different groups of animals. Examples in that thread where the animals in question are of different classical Linnaean classes (i.e. mammal vs reptile, mammal vs bird, bird vs reptile, etc., etc.) will stay in that thread, while I am thinking of transferring examples of combat between the same classes into their respective threads (i.e. move mammal vs mammal stuff into this thread, bird vs bird stuff in to 'Avian conflict', etc., etc.).

So here's a thread dedicated to conflict between mammals. Of course, that's still a very massive, broad topic, so any general accounts, images, and videos you can find of mammals fighting each other will be fine for this thread. Both intraspecific and interspecific conflict are acceptable. Fights are acceptable to post here except when they are directly induced by humans (so dog fighting or anything of the sorts has no place in this thread).


Here's a report of an adult roe deer doe killing a subadult doe (Roviani, 2014).

Here I report on a lethal attack by an adult doe to a subadult one. The latter, estimated at one year of age, was recognized as such by its body size and abdomen noticeably not concave, compared to the adult one. A subsequent inspection on the place where the carcass was lying, allowed an evaluation of tooth development and wear, confirming the previously estimated age. To my knowledge, no comparable interaction among females has ever been reported in literature for any ungulate species. The event occurred on the 28th of June 2013 in a valley just in the southern outskirts of the town of Siena (Tuscany, Central Italy). It took place in an overgrown abandoned meadow with a southern exposure, where grasses and herbs reached the height of 1-1.5 meters. Around the meadow, in a radius of 150 metres, there were olive groves, an orchard, scattered fruit trees, a stone pine Pinus pinea plantation, cultivated domestic gardens, woodlots and an abandoned vineyard. The vineyard has been a long-term refuge for several female roe deer throughout the year. Farther on, the valley opened to the countryside, with wheat Triticum sp. fields and small wood patches. What follows was observed with a 16×50 binoculars at a distance of about 50 metres. Most likely, the interaction observed was the end of a longer contest. At 08:00 PM, a fight between two roe deer females, a subadult and an adult, was taking place in an abandoned meadow. At the beginning of the observation, another individual was detected fastly moving away in the opposite direction with respect to the fight site, but its age and sex could not be determined. The attacks were solely carried out by the adult female to the subadult one, who appeared unable to react and already quite weakened. During the first recorded attack, the adult female first kicked the neck of the subadult with one foreleg and immediately after with its nose, probably biting or hitting the neck with her incisors, a detail that I could not detect because of the distance. Then, the subadult doe fell to the ground on its back and remained in this position completely motionless for a few minutes. Meanwhile the adult female cautiously approached the body of the subadult with its snout, seemingly to sniff and butt at her. A few minutes later the younger female managed to get up and made some leaps, immediately chased by the adult. Two more attacks with the same patterns were carried out by the adult doe, ending up with the attacked one immobile in the grass, with the other constantly gazing at her. Finally, the last attack was carried out hitting the abdomen with her snout (incisors?), displacing the younger female and making it fall on her right side. The adult female again sniffed and butted at her for a few minutes and then turned away. The observation ended at 08:20 PM. The subadult one did not move anymore from its final position after the interaction ended, and was considered dead. Unfortunately, due to logistical and temporal constraints, it was not possible to immediately retrieve the carcass and perform an autopsy. The night after, the carrion was eaten by unidentified carnivores. A necropsy would have assessed the health condition and the actual cause of death, e.g. bites, wounds, internal hematoma, infection caused by internal parasites. One other major limitation of my observations, is the fact that certainly the interaction had started earlier. As the period of births was just over, guessing what led the older female to this aggressive and unusual behaviour to a younger conspecific of the same sex may not be easy.

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Originally posted by Supercommunist in 'Animal conflict'.

Supercommunist Sadly, some of the videos posted in the original thread have become unavailable since they were first posted there, so I couldn't/can't transfer all material (I don't even know what the unavailable videos originally were). I'll try my best, though.

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Originally posted by Supercommunist in 'Animal conflict'.

[Exalt]

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Our results indicate that grizzly bears are the dominant competitor during interspecific interactions with polar bears at the feeding site, frequently displacing polar bears without displaying aggression. We rarely observed polar bears acting aggressively towards grizzly bears; if an individual acted aggressively in interspecific interactions, it was usually the grizzly bear. Conversely, in interactions among polar bears, aggressive interactions were more frequent. These results imply that polar bears attempted to minimize conflict with grizzly bears. Additionally, grizzly bears permanently displaced polar bears from the feeding site approximately 50% of the time during interactions. This is striking when one considers that losers in interactions between polar bears were only permanently displaced from the feeding site approximately 10% of the time.

While our results suggest that polar bears, overall, were subordinate to grizzly bears, there were differences among social classes in their responses to grizzly bears. Females with cubs tended to avoid the feeding site during periods when grizzly bears were most likely to be there; however, this was confounded by the possibility that females with cubs may have been avoiding potential interactions with adult male polar bears as well. Regardless of which bears they may have been avoiding, if females with dependent cubs encountered a grizzly bear they were more likely to act aggressively than other social classes. Lunn and Stirling (1985) demonstrated that nearly all aggressive interactions observed between polar bears at a dump during summer were initiated by females with cubs, and family groups were the most dominant; similarly, Stirling (1974) observed that females with cubs were not subordinate to any other sex or age class of polar bear when they were threatened.

The aggressive behavior displayed by females with cubs at the feeding site was likely in defense of cubs and not to compete for food. This is supported by our observation that females with cubs frequently used the feeding site when the presence of grizzly bears and adult male polar bears was less likely. Similarly, avoidance behavior by females with cubs has been observed elsewhere. For example, Pilfold et al. (2014) found that females with cubs used lower quality habitat than other social classes. Previous research has also shown that females with cubs tend to be segregated from other social classes while on land during the ice-free period (Derocher and Stirling 1990; Ferguson et al. 1997). Females with cubs are likely less willing to risk the loss of their cubs to utilize ephemeral resources (e.g., Derocher and Wiig 1999). Thus, beach-cast marine mammal carcasses might not be as readily available to females with cubs.

It is interesting that grizzly bears were socially dominant over polar bears given that dominance hierarchies among polar bears (Stirling 1974) and grizzly bears (Stonorov and Stokes 1972) are generally based on size differences between competitors. Grizzly bears along the northern coast of Alaska are much smaller (males: ~180kg, females: ~110 kg—Hilderbrand et al. 1999) than polar bears in the same region (males; ~375kg, females: ~195 kg—Rode et al. 2014), thus it is surprising that polar bears were frequently subordinate to grizzly bears. There are several hypotheses, however, that may explain this asymmetry.

First, grizzly bears in low-quality habitat such as the northern coast of Alaska (Ferguson and McLoughlin 2000) may be more motivated to engage in competitive interactions with other bears to obtain access to high-quality food resources (Smith et al. 2005) such as a marine mammal carcass. As an omnivorous species, grizzly bears are also more likely to defend an energetically rich food source (Boertje et al. 1988) when it is available, since low prey density and the rate at which they capture prey makes the availability of an energetically rich food source such as a marine mammal carcass a relatively rare event (Stirling and Derocher 1990). By contrast, polar bears have access to energy rich marine mammals (Stirling 1974; Stirling and McEwan 1975; Stirling and Archibald 1977) throughout most of the year.

Second, the 2 species have different energetic requirements at the time of year when whale remains are present. Grizzly bears begin their period of winter dormancy in autumn and are hyperphagic during late summer and autumn (Nelson et al. 1983). Conversely, polar bears are hyperphagic during spring rather than autumn (Ramsay and Stirling 1988). Polar bears in the southern Beaufort Sea are at or near their minimum body mass for the year in late March (Cherry et al. 2009). Hyperphagic behavior in spring allows polar bears to increase their mass when food availability (e.g., ice seal pups) is highest (Stirling and Øritsland 1995). When polar bears are onshore in summer and autumn, reduced prey availability can result in the onset of a fasting physiological state similar to hibernation in other bear species (Nelson et al. 1983; Derocher and Stirling 1990; Cherry et al. 2009). Polar bears in good nutritional condition may therefore be unwilling to expend the energy required to outcompete grizzly bears during this time of year. Conversely, grizzly bears den in autumn and must acquire adequate fat reserves prior to hibernation (Nelson et al. 1983; Lunn and Stirling 1985). Grizzly bears may, therefore, be more likely to compete for food sources in autumn in an effort to maximize the amount of stored fat reserves that they build up before denning.

Another explanation for why grizzly bears were dominant to polar bears may be related to their evolution. Throughout their evolution, the presence of large Pleistocene predators such as wolves, large cats, and other bears (e.g., Matheus 1995; Leonard et al. 2007) resulted in natural selection for aggression in grizzly bears which foraged in open, nonforested habitats (Herrero 1972; 1985). Polar bears, having evolved to exploit a specialized sea ice niche, did so largely in the absence of competitive influences from the suite of terrestrial Pleistocene predators that influenced brown bear evolution.

Lastly, the consequences of fighting an unknown competitor and risking injury may be a factor influencing brown bear social dominance over polar bears. While all North American bears generally exhibit risk-averse behavior and rarely engage in actual combat unless the reward is high, e.g., during breeding (Herrero 1985), the risk of injury to polar bears may have more severe consequences than to grizzlies because they are obligate carnivores and depend on their ability to hunt for survival. Polar bears may be less willing to invest in aggressive behavior against an unknown grizzly bear competitor because, if a polar bear is seriously injured, its ability to hunt will be severely limited. Conversely, grizzly bears are omnivorous and could possibly sustain a serious injury more readily, given their ability to utilize vegetative food resources. Additionally, polar bears are likely more aware of each other’s competitive status, given the “risk-free” social play that occurs while on land in summer (Latour 1981). For example, in our study area, polar bears aggregated on a nearby barrier island during the day where they had opportunities to interact with each other. We often observed groups of adult male polar bears resting in very close proximity to one another in “bachelor groups” on barrier islands during the day. These individuals displayed strikingly benign behaviors, such as licking each other’s mouths and sleeping adjacent to each other. Similar behavior by grizzly bears has not been reported, perhaps because their evolutionary history has selected for aggression to defend resources (Herrero 1985), and their low population density in high latitudes minimizes social interactions (Smith et al. 2005). During our study, polar bears only encountered grizzly bears at the feeding site, thus they were unable to assess grizzly bear competitive abilities in a “risk-free” environment. We do not know, however, whether previous encounters with grizzly bears may have affected polar bears’ responses to grizzly bears, i.e., whether past experience led to avoidance behaviors that served to prevent potential injury.

academic.oup.com/jmammal/article/96/6/1317/1174934?login=false#20496713

[Exalt]

I'm posting this one for a few reasons:

1. I don't think that I've ever heard a porcupine noise before.

2. I didn't even know that leopards and porcupines could meet.

3. This would seem to imply that porcupines are among the relatively few mammals where the father is involved in parenting.

4. It demonstrates how some predators actually approach the challenge of the porcupine's quills.

5. It shows how much larger the quills make the porcupines appear.

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A moot of mine on Twitter shared these. Apparently there was an incident where 8 wild dogs killed an adult male lion.



Similarly, there was apparently a "war" in Tanzania between hyenas and lions. There was a lion-hyena war in Ethiopia in 1999 where the lions won. But this time the hyenas did, losing 6 of their own but killing 9 lions, two of which were the pride males.

[Supercommunist]

I think the first account is plausible, especially if the male lion weren't in great shape but the second seems rather unlikely. Lions are faster than hyenas. They might not have the best stamina I can't envision many scenarios were nine of them are killed by hyenas in one engagement and its strange how the hyenas have less casualties.

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I don't think this was just one engagement. The war in Ethiopia in '99 lasted two weeks, and the total kill count must have been that which accumulated over that entire time span. I assume the same is true for this one.

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Impala that probably got its eye gouged out from a fight with another impala (link->).