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The world’s largest hornet is the Asian giant hornet (Vespa mandarinia). An individual specimen can measure up to 5 cm (2 inches) long and has a wingspan of 7.6 cm (3 inches). Giant hornets have blunt wide heads which look different from those of other wasps, hornets, and bees and they are colored yellow orange and brown.
The Asian giant hornet ranges from Siberia down across the Chinese coast into Indochina and lives as far west as India, however the hornet is most common in the rural parts of Japan where it is known as the giant sparrow bee. The sting of the Asian giant hornet is as oversized as the great insect is. Within the hornet’s venom is an enzyme, mastoparan, which is capable of dissolving human tissue. Masato Ono, an entomologist unlucky enough to be stung by the creature described the sensation a “a hot nail through my leg.” Although the sting of a normal honey bee can kill a person who is allergic to bees, the sting of an Asian giant hornet can kill a person who has no allergies–and about 70 unfortunate souls are killed by the hornets every year.
Armed with their size and their fearsome sting, Asian giant hornets are hunters of other large predatory insects like mantises and smaller (i.e. all other) hornets. The giant hornets do not digest their prey but masticate it into a sticky paste to feed to their own offspring. A particular favorite prey is honey bee larvae, and since European honey bees have no defense against the giant wasps, all efforts by Japanese beekeepers to introduce European bees have met with failure. Japanese honey bees however have evolved a mechanism (strategy?) to cope with hornet incursion. When a hive of Japanese honey bees detects the pheromones emitted by hunting hornets, a crowd of several hundred bees will form a gauntlet (carefully leaving a space for the hornet to enter). Once the hornet walks into the trap the bees rush on top of it and grasp it firmly. They then begin to vibrate their flight muscles which raises the temperature and produces carbon dioxide. Since giant hornets cannot survive the CO2 levels or high temperatures that honey bees can, the hornets put up a titanic struggle to overcome the mass of bees, killing many in the process. However honey bees have a fanaticism which would do credit to the most ardent practitioner of Bushido, and they usually kill the invaders.
Yesterday’s post—which featured a gory painting of medieval deer hunting—makes one feel sorry for the poor beleaguered deer, which are surely among the most beautiful and graceful of all animals. And those painted deer were being pursued by crossbow hunters—imagine how much worse things would be with high-powered rifles. Well actually you don’t have to imagine–here in North America, the dominant cervid, the magnificent white-tailed deer (Odocoileus virginianus) was severely overhunted in the 1800’s as hunters shot wild deer and sold the venison at the market. Deer populations crashed down below 400,000. Entire regions of the country lost the white-tailed deer completely. The sacred animal of Artemis was in deep trouble across the United States.
To rectify this situation, the Lacy Act, the first federal wildlife law, was passed in 1900. The law banned the interstate trafficking of venison (along with other wild game). Then the Great Depression and the Second World War came along and everything changed again. During the Depression, rural landholders were forced to move into cities to make a living and land which had been under the plough began to grow back into forest. When World War II broke out a generation of hunters went abroad to shoot at the Axis instead of whitetails. After the war, in the 1950s, a clever biologist named Crockford invented a dart-gun system for capturing white-tailed deer and releasing them into habitats where they had died out. So deer made a comeback but their predators did not. Wolves, grizzlies, cougars, jaguars, alligators, and lynxes were relegated to the deep forest and swamp of protected national parks.
So by the end of the twentieth century, white-tailed deer populations were spiking out of control (heading to well above 30 million) and this in turn had a terrible effect on the forests. When a forest is partially or wholly timbered (or when it is denuded by some natural means such as a tornado) there is a succession of plant growth which after decades leads back to a mature hardwood forest. The first plants to grow back are meadow plants–short-lived annual herbs and meter-tall woody plants. Over the course of years these weeds give way to hardwood seedlings like oak and maple which can tolerate the shade created by the provisional meadow growth. However, in areas overpopulated by deer, the woody meadow plants are nipped up by starving deer and other tree seedlings which can out-compete the great forest trees for nutrient gathering (but which are not shade-tolerant to survive the meadow plants) then flourish. Beeches, wild cherries, or exotic invaders grow up and the trees of the great forest take lifetimes to supplant them (if they do at all). In the meantime the overpopulated deer begin to starve and suffer diseases even as they damage the forests. A strange truth of ecosystems is that predators are nearly as necessary as their prey—even hardy generalists like the white-tailed deer which can live almost anywhere need population controls for their own good (as well as that of the forest). Perhaps the ancient Greeks were wise to decide that their goddess of the wilderness was both a hunter and a protector of animals and trees.
Biologists, foresters, rangers, and sportsmen are all trying to unscramble the secrets to ecosystem equilibrium, but there might not be any real long-term balance. The tropical swamps and forests of the Eocene gave way to the temperate woodlands of the Oligocene (where the first tiny deer developed in Europe) which in turn led to the savannahs of the Miocene which allowed artiodactyl grazers to radiate out across the world. But it is hard to think in such big terms and it is uncomfortable to think about what will come next. Something within me longs for homeostasis—for the right number of lovely deer beneath the tall native oaks and tulip poplars forever and ever.
Since I have already written so many mammal posts I am creating a new blog category for mammals (I will leave out human concerns to concentrate on zoologic overviews of other species, but please remember that technically we too are mammals and all of the posts on this and every website could fall under this category). To make way for the mammals I deleted the “celebrity” topic for good (I had hoped to make fun of our queasy fascination with lackwit celebrities–but other than an one sighting of the disquieting Richard Simmons, I had nothing). Begone vile celebrities! The age of the mammals has dawned.
I already have plenty of posts about goats, pigs, wombats, hyraxes, and bizarre intelligent monotremes with which to populate this category, but to kick the topic off properly I am writing today about the alpha-predator of the Amazon. This mammal is the king of the Mustelidae (also known as the weasel family) and, if you have ever seen a lightning fast stoat hunting a rabbit, or smelled a skunk, or watched a badger drive off a bear, or witnessed a wolverine tear apart a moose, you will know that the weasel family is not joking around. [ed: what? When did you see any of this?] The largest mustelid is a particularly magnificent creature—the giant otter (Pteronura brasiliensis) which lives throughout the Amazon basin and Pantanal. The giant otter is a long animal and males are up to six feet (2 meters in length) and weigh up to 100 pounds (45 kilograms). Much longer males measuring nearly 8 feet in length were once reported but it is believed that extensive hunting may have eradicated all of the really giant giant otters.
Giant otters are tremendously accomplished fishers living largely on cichlids, characins (such as piranha), and catfish, but, as an apex predator they are opportunists who supplement their diet with snakes, crabs, turtles, and caimans. Although the otters are diurnal predators who hunt at daytime using their large acute eyes to find their prey, their hearing is also excellent and they possess extremely sensitive vibrissae (whiskers) to gauge the faintest water current. Like other mustelids, giant otters have fast metabolisms and they eat about 10% of their body weight per day. Their adaptations to aquatic life include webbed feet, ears and nostrils which clamp shut, powerful tails for swimming, and incredibly dense fur. As with their cousins the sea otters, this valuable fur proved to be their undoing. During the nineteenth and early twentieth century they were hunted to the very threshold of extinction by furriers (and by fishermen who regard them as a clever nuisance). Their numbers still remain low today: only 2,000-5,000 giant otters are estimated to live in the wild.
Giant otters form family groups around a mated pair. Older offspring from years past stay with this pair and help out rearing the young cubs before venturing off on their own. They travel widely through the inundated forest during flood seasons and spend the rest of the year based around a fishing camp which they build beside a lake or a choice stretch of river. These camps consist of large multiple entrance home dens built under and around tree roots as well as several secondary locations (along with communal latrine areas). The otters might also alter river beaches to be more to their liking by removing vegetation. The fur of the giant otter is usually brown, red, or fawn and the otter’s bib is marked with cream and white stipples. These are for identification purposes: otters “persiscope” up out of the water to get a better view of each other and to learn whom they are meeting. Giant Otters are also famous for their complicated (and loud) vocalizations.
Although the adult giant otter has no natural predators, young otters must look out for caimans, jaguars, and anacondas. Additionally the giant otters compete for prey with these creatures as well as with river dolphins, large predatory fish, and large turtles. The otters are always on the lookout for dangerous stingrays and electric eels. None of these natural threats, however, are particularly significant compared with the threat from habitat loss, logging, mining, and industrial pollution.
Some of the native humans indigenous to the great river basins believed the otters were river spirits who had, once taught valuable lessons to the first humans. Other native peoples (particularly fishing people) held that the otters were worthless nuisances to be killed or run off whenever sighted. Such sightings however grow increasingly rare as the giant otter, the longest mustelid, vanishes forever away from all but the wildest places in the rainforest.