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carnassials
red fox’s four-continent range,
Given that the red fox now inhabits a staggering 83 countries,
many ecosystems are now jumbled jigsaws, missing some pieces, with invasions of non-native species confusing the picture further.
Foxes have 42 teeth inside their narrow muzzles, among them the trademark of the order Carnivora. Their last upper pre-molar and first lower molar are called carnassials, modified with a tall shearing edge for slicing flesh. All 300 or so Carnivorans possess carnassials. Your pet cat has them – in fact they are exceptionally well developed in felids, which are the most meat-specialised of the entire order. Pandas, on the other hand, have flattened carnassials because they are largely vegetarian.
But foxes of all species are undeniably canid, that is, members of Canidae, the dog family. Turning the skull over, the base of the ear sockets is fused into a bony casing called a tympanic bulla, protecting the fragile inner-ear bones. In canids it is uniquely divided by a septum: a thin, bony wall. It is believed that this extra echo-chamber enhances their ability to hear low frequencies.
Five toes with claws that are not fully retractile, a long muzzle filled with delicate turbinal bones that magnify smells, the nuchal ligament that strengthens their necks to allow them to run for extended periods with nose to the ground – the physical hallmarks are unambiguous. The fox is a dog.
Prohesperocyon – the first known canid – was a small, omnivorous creature in a forest of astonishing giants, a natural neighbour to the likes of the fearsome Nimravidae, sabre-toothed carnivores resembling great cats. As Earth gradually cooled and dried and the dense jungles were replaced by extensive grasslands, the elongated legs and long strides of the canid body shape clearly provided an advantage in long distance chases. Canidae thrived.
We live in an interglacial now called the Holocene. It has lasted nearly 12,000 years, but it probably won’t continue forever.
But 16,000 years ago, when Palaeolithic painters were drawing steppe bison in the Spanish cave of Altamira, a woman of unknown name died in what is now Jordan, in a site called ‘Uyun al-Hammam. Her body was laid among flint and ground stone, and a red fox was carefully placed beside her ribs, resting with her for eternity on a bed of ochre.
The Tale of Genji,
The world is full of magic things, patiently waiting for our senses to grow sharper. W. B. YEATS
The culprit is the tapetum lucidum, a remarkable layer of tissue directly behind the retina. Present in many creatures that are active in low light levels, from fish to tigers, it reflects visible light back through the retina, effectively brightening the world for its owner.
In bright light, a dog’s pupils contract to a round shape, which is not surprisingly also the case for the ancestral grey wolf. But a fox’s pupils contract vertically, like those of a small cat. Is this an advantage? Absolutely. Canid eye lenses contain concentric zones of different focal lengths, and a vertical pupil can exploit all these zones even when at its narrowest in bright light. This improves the focusing of long and short wavelengths of light, reducing or eliminating chromatic blur/haze in bright conditions. In short, foxes are multifocal.
Slightly offset from true north, the Earth’s magnetic north pole drifts each year due to the behaviour of molten iron in the planet’s outer core. The invisible magnetic field that envelops our planet protects us from harmful cosmic rays while also playing host to the geomagnetic storms that produce spectacular auroras: the northern and southern lights.
Foxes may use the directional information from the magnetic field together with auditory input from the vole’s rustling to move to a fixed distance from the target, allowing a precise leap. If so, foxes are the first species known to use the magnetic field as a measure of distance.
Attached to the sagittal ridge are the temporalis muscles, which are used for biting. The bigger the ridge, the more powerful the snap of those jaws.
We have learned of this species Sherlockian-style, piecing its life together from minute details of the bones it has left behind, mostly in the macabre La Brea Tar Pits of California. This lethal but fossil-rich site has gifted museums a grand surplus of dire wolf skeletons. One is now on display at the Natural History Museum in London,
Bergmann’s rule – the ecological principle that in a species with a broad geographic range, individuals in colder climates are likely to be larger.
The standard fox colouration is of course rich orange on its upper parts, with a white chin, throat and belly, and legs darkening to near-black. The brush usually but not always has a white tip. The hindquarters are usually more muted than the front.
Genuinely melanistic foxes are highly unusual in the UK, but there are a few records from London and the Home Counties. They are much more common in North America, along with a part-melanistic variant known as the cross fox – a strikingly handsome animal with orange upperparts and a black face and belly. Another colour morph a few steps down from full melanism is having an orange back and
Why is it more common in NA?
dark chest;
At the other extreme, foxes can be dazzlingly white. If you should spot a snowy fox trotting across your lawn, this does not necessarily mean that an Arctic fox has escaped from a nearby zoo. It is probably a wild red fox that is demonstrating leucism – a sharp reduction in pigment levels caused by the failure of the melanocytes to migrate during cell development. The result is a mesmerising animal that is almost entirely furred in white; it may still show black ‘moustache’ ...
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fox family – officially known as a skulk, although the term is seldom used
The brains of wolves and other group-hunting canids are structurally more complex than those of foxes. They contain a dimple in the coronal gyrus (in the frontal region), and a significantly larger prorean gyrus. Although difficult to test, it is believed that these additional brain folds relate to the wolf’s sophisticated social behaviour.
Remarkably, she is only fertile for three days a year, usually in the week after Christmas.
British foxes rarely encounter prolonged snow, but they deploy identical arching leaps – called mousing jumps – upon short-tailed field voles.
Adolph Murie, the founding father of wolf research, investigated their relationship as long ago as the 1940s, and concluded that they could coexist in good numbers. He did discover a certain degree of mutual theft – foxes need no second invitation to help themselves to the leftovers of wolf-killed deer, and wolves readily dig up any caches that a fox has buried. They also steal earths. Every wolf den that Murie located in Alaska’s Denali National Park was an enlarged ex-fox den. Many wolf dens in Białowieża are also acquired from foxes.
North America’s wolves were aggressively targeted by predator eradication campaigns, coyotes stepped into the canid vacuum. While the grey wolf became a threatened species and the red wolf nearly disappeared from the world altogether – current estimates of the wild population are around 30 individuals – coyotes adapted, bred more successfully, and vastly expanded their range. Today, coyotes are found from Alaska to Panama. And the impact on foxes? The rule of thumb is that they actively avoid coyotes. As the grey wolf recovers its range in North America and elsewhere, coyotes themselves have
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Some of their sweet musky odour originates from the violet or supracaudal gland, which is found about a third of the way down their brush.
This fits with the conventional model that territories are really the construct of male foxes; a vixen, rather like a Victorian woman, holds property only as a proxy of her mate.
The fierce selfishness of this social system – technically intraspecific competition – locks fox populations at a density far lower than any external force ever consistently could.
Free speech may be the mark of a democracy, but even in these days of social media, speech is absolutely not financially free.
Today it is present in at least 104 species, including critically endangered African wild dogs and Ethiopian wolves, as well as pigs, llamas, and lynx.
Mange
We have built our world over the wildwood, and yet seem perpetually surprised that foxes are in it; it is a whimsy of the human race that we love wild animals that collapse towards extinction in our presence, and resent those that survive us.
Science cannot slay dragons that do not exist; it cannot solve problems that are not occurring.
