A comparison of honey badger and wolverine, part 2

...continued from https://www.inaturalist.org/journal/milewski/66983-a-comparison-of-honey-badger-and-wolverine-part-1#

The external ears of our two species differ categorically. This is related to the differences in anti-predator defences.

Based on climatic adaptations, one might expect the wolverine to have the smaller ear pinnae, in line with other cold-tolerant mammals that have reduced all heat-losing surfaces of the body.

However, it is the honey badger that is unusual for a carnivore in lacking distinct ear pinnae, despite having good hearing. Its wide ear openings (https://www.alamy.com/honey-badger-image386098154.html and https://www.alamy.com/stock-photo-honey-badger-mellivora-capensis-view-from-the-side-close-up-52743421.html and https://www.alamy.com/honey-badger-mellivora-capensis-image414399384.html) can close by means of transverse valves to exclude dirt and insects.

This reduction of ear pinnae in the honey badger is hardly explained by either climate or a commitment to excavating its food – especially in view of the obvious ears of other species of badgers (i.e. Meles https://www.inaturalist.org/observations?place_id=any&taxon_id=41840&view=species and Arctonyx https://www.inaturalist.org/observations?place_id=any&taxon_id=41842&view=speciesof Eurasia and Taxidea https://www.inaturalist.org/taxa/41789-Taxidea-taxus of North America) and the particularly large ears of other digging mammals sharing its habitat.

The aardvark (Orycteropus afer, https://www.inaturalist.org/observations?place_id=any&taxon_id=47062&view=species), for example, is an extreme digger with donkey-like ears; while the bat-eared fox (Otocyon megalotis, https://www.inaturalist.org/taxa/42095-Otocyon-megalotis) also has large ear pinnae despite, like the honey badger, living in burrows and listening for the rustlings of buried insects after an exploratory scratch.

The 'earlessness' of the honey badger is consistent with the toughness and looseness of the rest of its skin. In particular, it minimises surfaces exposed to stings/bites of insects as well as the grip of large enemies such as the spotted hyena.

LOCOMOTION

Both the honey badger and the wolverine have massive forepaws and versatile limbs and are thus capable climbers, swimmers, runners and diggers. However, the honey badger is essentially like an earthmover, whereas the wolverine is essentially like a snowmobile.

This is because the first species has bare soles, like most plantigrade carnivores, whereas the second has partly furred soles for insulation, emulating its occasional prey, the snowshoe hare (Lepus americanus, https://www.inaturalist.org/taxa/43132-Lepus-americanus).

(Plantigrade mammals walk by placing the entire soles of the feet on the ground. The local form of honey badger in the Himalayan foothills seems to be exceptional in that its hind soles may be partly fur-covered.)

Admittedly, the wolverine excavates snow to make deep dens, and is capable of seasonally digging out ground squirrels to kill them, and then digging them back into the earth as a cache for later consumption. But it is the honey badger that digs every day for its staple diet.

Further evidence of the dedication of the honey badger to earthmoving is the sheer length of fore-claws two, three, and four, which exceeds even that of the European badger (Meles meles): an average of 3.8 cm, and ranging up to 4.6 cm. Although the three longest, strongest fore-claws of the honey badger fit neatly together into a single rigid unit when digging, the species retains some dexterity because the same digits retain an ability to spread and to move individually – for example when it climbs trees or pulls a porcupine spine from its skin.

The fore-claws (2.4-2.6 cm) of the wolverine, which are conspicuously pale against the dark fur of the paws (https://www.dreamstime.com/stock-photo-paws-wolverine-gulo-gulo-closeup-image-front-rock-image79115898), are short relative to bears as well as the honey badger.

I suspect that the fore-claws of the wolverine - which do not normally contact ground surfaces other than ice - are designed to remain sharp, whereas those of the honey badger are designed to resist wear. This apparent difference is reflected in their approach to tree-climbing.

Partly by virtue of hind-claws that are longer (2.2-2.4 cm) than those of the honey badger (only 1.0-1.8 cm), the wolverine can cling to tree trunks in a cat-like manner. It relies on climbing quickly enough in emergencies to evade its main enemy – the wolf (Canis lupus).

By contrast, the honey badger is unknown to climb trees when in mortal peril. And when it climbs for food, it seems happy simply to fall the last three metres in its descent.

The running gaits of our two species have different emphases despite their similar body forms. The limb actions differ according to their respective modes of deep digging versus fleet-footed scurrying over snow.

The honey badger consistently trots with its back held low and straight, whereas the wolverine canters with a flexed back and - unlike the honey badger - is able to jump. The is consistent with:

• the extremely long fore-claws of the honey badger, which prevent the animal landing on its forepaws, and
• the adaptation of the wolverine to snow and rocks.

Unlike the wolverine, the honey badger can reverse rapidly (scuffling backwards) in confrontation with large-bodied carnivores (https://www.youtube.com/watch?v=SCEIAwatlV8).

The honey badger is reminiscent of otters in lying on its back and cradling food items such as melons on its belly while eating them. I have seen no evidence of similar postures in the wolverine.

DIET

Both species

• forage year-round and have relatively broad and unfussy tastes,
• eat various rodents, birds, and eggs where available, and
• are opportunistic enough to help themselves to the flesh of large mammals – even if this means driving large carnivores temporarily from their kills.

However, the honey badger basically depends essentially on venomous prey, whereas the wolverine basically depends on well-preserved or cached carrion.

Records of raiding human camps and destroying food in metal cans and other stout containers are particularly frequent for the wolverine. However, the honey badger sometimes behaves similarly, for example at Paradise Bush Camp in Balule Nature Reserve, Limpopo Province, South Africa (source: Craig Spencer, Afreco’s blog, http://afrecotours.wordpress.com/).

The honey badger ranks above its weight among African carnivores. And I suspect that the honey badger is a considerable predator on Hystrix africaeaustralis, H. cristata, and H. indica, which are collectively sympatric with it over virtually its entire range and in virtually its entire spectrum of habitat. However, only the wolverine actually kills prey as massive as the moose (Cervidae: Alces alces) – the largest-bodied animal in its habitat.

The honey badger Can coexist with superior carnivores, and it has a plausible reputation for occasionally injuring large-bodied herbivores in bad temper. However, the staple diet of the honey badger is not ungulates but rather invertebrates (such as scorpions, termites, hymenopteran (i.e. bees, wasps, ants, and other stinging insects, many of which are social/colonial, and large dung beetles), reptiles (including monitor lizards, hard-shelled tortoises, and extremely venomous snakes), and the infants of larger mammals. Most of these are routinely excavated from hollow trees or below ground.

By contrast, a major part of the winter diet of the wolverine is frozen carcases of large-bodied mammals which have succumbed to mishap rather than being killed by any predator.

The difference in their staples is partly because the habitat of the wolverine is too cold for the invertebrates and reptiles that make up much of the diet of the honey badger. The wolverine does eat the larvae of wasps during the brief summer. However, in the far North, the main raiders of the hives of venomous social insects bears, including the black bear (Ursus americanus) - which is similar to the honey badger in concentrating on invertebrates in the animal part of its diet.

Where the wolverine differs is that it is effectively a top carnivore on the reindeer or caribou (Rangifer tarandus), the most plentiful species of ungulate in the northernmost part of its range. Rather than being inferior in guild of competitors for the fresh meat and bones of this species, it is a powerful predator and scavenger - which can win a contest for a carcase with a single individual of the wolf.

Furthermore, the wolverine can negotiate rocky slopes and remains competitive even on flat ground, because wolves and bears tend to sink into snow over which the proportionately broader-footed wolverine can canter/gallop when fleeing or foraging.

There is scant evidence, empirical or circumstantial, for the oft-mentioned symbiosis between honey badger and honeyguides (particularly the greater honeyguide Indicator indicator https://www.inaturalist.org/taxa/17570-Indicator-indicator). The churring bird allegedly leads the honey badger to beehives in return for the scraps left after the destructive mammal eats its fill.

Any facilitation between these animals is more likely to go the other way, with the honeyguide following the mammal as several medium-size birds of prey are known to do.

There is scant evidence that the honey badger even eats much honey in the first place. It seems that the raiding of hives – as with most other mustelids – is rewarded mainly by the bee larvae rather than the honey. Perhaps this is because the honey badger seeks nutrients rather than energy from the hives.

The honey badger has fewer teeth (32) than the typical member of its family (34). By contrast, the wolverine shows the opposite deviation with its 38 teeth – just 2 short of the 40 attained by the European badger. The upper canines of the honey badger are shorter than in most other carnivores, its relatively short row of premolars being sufficient for its mainly small prey, and its molars tend to be worn flat by grit in a way not seen in the wolverine.

For their part, the molars of the Northern species are set at right angles to the premolar row – which may be explained by the traction needed to tear off pieces of meat from solidly frozen carcases and to bite on bones. The honey badger, unlike the wolverine, has not been observed to eat large bones despite the ability of its teeth to break stout wire. The wolverine, unlike the honey badger, rivals the much larger wolf as a bone-crusher.

This makes sense given that hyenas occur in the habitat of the honey badger but not in the habitat of the wolverine. Unable to compete for bones, the honey badger instead concentrates on venomous and gritty foods which even the smallest hyenas seem unwilling or unable to exhume.

Indeed, even when eating large mammals and the largest snakes (such as the African rock python Python sebae https://www.inaturalist.org/taxa/32152-Python-sebae), a snake with an adult body mass up to four-fold that of the honey badger, the honey badger pulls out the innards through any small hole in the skin, rather than attempting to chew strips through the hide; this shows that its carnassial (the carnassial teeth (mainly premolars) operate like shears in slicing meat) dentition is unexceptional among carnivores even though its vice-like bite can mangle steel.

The contrasting ability of the wolverine to eat large bones makes sense in terms of access and need. This is because carcases and skeletons tend to lie undiscovered in its frigid habitat for long periods and few other foods are available in winter.

The skull of the honey badger (http://skullbase.info/skulls/mammals/honey_badger.php and https://animaldiversity.org/collections/contributors/skulls/mellivora/m._capensis/umnh296107.head-on/ and https://www.thetaxidermystore.com/honey-badger-full-skull-taxidermy-mount-for-sale-22062.html and https://wakingupwild.com/photography/guides-feathers-skulls-artifacts/animal-skull-identification-guide/honey-badger-10/) shows the relatively small canines and poorly developed carnassials (https://en.wikipedia.org/wiki/Carnassial).

The skull of the wolverine (http://digimorph.org/specimens/Gulo_gulo/female/ and http://www.mammalogy.org/gulo-gulo-1297 and https://www.darwinandwallace.com/collections/mammal-skulls-skeletons/products/wolverine-skull-gulo-gulo and https://www.worthpoint.com/worthopedia/real-alaskan-wolverine-skull-great-11905276) shows that the canines are larger, the carnassial premolars are sharper, and the incisors more crowded than in the honey badger.

Both species have fang-baring expressions. However, that of the wolverine is particularly well-developed (https://www.reddit.com/r/natureismetal/comments/jp7o1y/this_wolverines_snarl/ and https://www.vancouverisawesome.com/animals/fierce-bc-animal-wolverine-hyena-north-2037486 and https://www.bbc.co.uk/programmes/p06mvchc and https://www.alamy.com/wolverine-gulo-gulo-snarling-image344200298.html and https://www.agefotostock.com/age/en/details-photo/wolverine-growling-haines-alaska/FLI-fim8961/1 and https://www.imago-images.com/st/0059449367).

INTELLIGENCE

Any differences in intelligence between the two species remain unclear. However, it is known that both remain playful as adults, suggesting cognitive superiority over other carnivores such as felids. In general, particularly encephalised species of animals tend to play not only as juveniles but also as adults.

Indeed, the honey badger has an unusually large brain for a mammal of its body size. It is the only terrestrial carnivore known to be capable of using tools, having repeatedly been observed rolling, carrying, or propping up objects such as logs to aid a climb to an otherwise inaccessible food item or escape route. Cognition of this sort, although emulating monkeys and apes, is beyond any cat, dog, hyena, raccoon, or mongoose.

While reports of innovative behaviours in the wolverine (e.g. when confronted with metal traps) sound on a par with those for the honey badger, I have not seen specific information on tool use or brain size for the Northern species.

The intelligence attributed to both honey badger and wolverine is unexpected in animals with aposematic colouration. For example, the striped skunk (Mustelidae: Mephitis mephitis https://www.inaturalist.org/taxa/41880-Mephitis-mephitis) seems no more intelligent than the average mammal; which makes sense in a species relying on gross deterrence rather than tactical complexity.

Furthermore, few aposematic species are viewed by humans as potential pets. It is therefore counterintuitive to find that the honey badger can be one of the most endearing of companions if hand-raised by humans. Indeed it seems to thrive in captivity despite its continual, non-territorial roaming in the wild. Some individuals are said to be consistently affectionate, even desisting from scent-marking to some degree as if in consideration of their human keepers. (The scent of one hand-reared juvenile individual was, in my experience, similar to that of strong-smelling human armpit.)

The few attempts to raise infants of the wolverine by hand have so far not revealed a similarly sweet nature in adulthood.

CONCLUSIONS

There may be different reasons for the extreme toughness of our two species. Whereas the honey badger has been forged mainly by an extreme biotic (biological) environment, the wolverine has been forged mainly by an extreme abiotic (climatic) environment.

The honey badger weathers intense antagonism in which predators and prey take defensive and venomous forms. By contrast, the wolverine, although equally hardy in its own way, lives in a climate so harsh as to exclude most other carnivores.

Indeed, the honey badger and the wolverine seem specialised mainly for self-defence and emulating larger carnivores, respectively. This makes sense given that the habitat of the honey badger supports many large predators whereas that of the wolverine supports only a few species of large predators in scattered and fluctuating populations.

A combination of antagonism and intelligence has given the honey badger what seem to be two faces: in the wild state a pig-eyed individualist, but in human care a playmate even more reciprocal than the domestic dog. For its part, the wolverine -being a diminutive combination of hyena and all-round carnivore - has the ‘small guy complex’ of a bantam-weight brawler.

The resemblance between the two species may, then, be fortuitous: a sinewy convergence arising from a similar tempering by disparate environments.

Posted on June 8, 2022 07:29 PM by milewski