Spotlight on urban wildlife: Foxes

Article, images and video by Dr Julie O’Connor, senior conservation partnerships officer, Sunshine Coast Council

A few things you may not know about foxes

Since the unfortunate introduction of the European red fox into Australia, it is widely agreed that it has been a major threat to some mammal species, particularly in the acute phase immediately following its arrival in new areas. The effects of fox predation on native species are well documented in government and research literature, so I will assume its reputation and legal status as a pest species is well known to you. The purpose of this spotlight on urban wildlife series is to acquaint you with wildlife, both introduced and native, who share our urban habitat. So, putting aside all the undesirable elements of the fox’s presence in Australia, here’s a few behavioural and physiological traits that are just downright interesting.

Communication

Foxes use a variety of body postures, facial expressions and vocalising to communicate with each other. Body postures are very similar to those observed in the domestic dog, e.g., arching the back and snarling in an aggressive posture, hackles raised to make themselves appear bigger to their foe, tail wagging when greeting another family member, and slinking and crouching low in the presence of a dominant fox. When fighting, foxes will sometimes stand on their hind legs with forelegs on each other’s chests, moving back and forth in what looks a little like a ‘foxtrot’, although it wasn't the inspiration behind the naming of that graceful dance.

In addition to body postures and facial expressions, foxes use a variety of vocalisations to communicate with each other, the most famous of which (especially if you watch any British crime series!) is the fox scream. So similar to a human scream is it that police in the UK sometimes receive calls reporting a woman being attacked (view video).

Researchers have identified 40 basic forms of sound production, which are used to create 28 groups of sounds. Visit Wildlife Online for some of the other more commonly heard fox vocalisations.

Foxes also communicate through the careful placement of urine and faeces and sniffing of the same. It is not unusual to find fox faeces on partially eaten prey items and also in prominent positions such as atop a rock or clump of vegetation at the nose height of other foxes. Urine is also used to convey a lot of messages, including the hormonal state of the vixen. Given that the vixen only comes into oestrus for three days once per year, accurate advertising of her reproductive state is important to both her and her mate.

Urine is also used in a complex food marking system that reminds a fox that food has already been retrieved from a cache site where a food smell might still be present. By doing this it avoids expending valuable energy digging for food that is no longer there.

Using the Earth’s magnetic field to hunt

Perhaps one of the most extraordinary discoveries in fox behaviour and physiology is the discovery that foxes align their bodies with respect to the Earth’s magnetic field to enhance hunting success.

Researchers in the Czech Republic found that stalking red foxes generally align themselves in a north-eastern direction before ‘mouse pouncing’ (the ‘mouse pounce’ is a common play hunting technique practiced by cubs. Foxes used the technique in snow but also in areas of high vegetation cover, where visual clues were reduced or not available. In areas of high cover, 74% of successful attacks were aligned within 20° clockwise of magnetic north. Attacks aligned to the south were also highly successful (60%), while pounces in other alignments had success rates less than 18%. Where prey was taken in low vegetation where the fox could see its prey, the directional alignment of the pounce was random. The researchers suggest that red foxes use the inclination of the earth’s magnetic field as a component of a targeting system to measure distance to its prey.

Foxes are not the only mammalian species who spontaneously align their bodies with respect to the earth’s magnetic field. Interestingly, in stable magnetic field conditions, domestic dogs prefer to defecate with their bodies aligned along a north-south axis, which could explain why your pet dog will often go around in circles before deciding where to anoint your lawn.

Will a fox breed with your pet dog?

The short answer is a definitive – no. Some other canids can and do successfully breed with dogs but foxes are not among them. The canids that can hybridise include the domestic dog, wolf, coyote and jackal, all of which have 78 chromosomes arranged in 39 pairs. The red fox, on the other hand, has only on average 38 chromosomes (this is actually slightly variable due to its possession of 34 metacentric chromosomes and from 0 to 8 small B chromosomes).

Although dogs and foxes might occasionally show sexual interest in each other, a productive outcome would be virtually impossible. So, while foxes have made themselves quite at home in some urban areas, their use of human hospitality won’t extend to mating with your pet dog.

References

• Cerveny, J. Begall, S. Novakoka, P. and Burda, H. 2011. “Directional preference may enhance hunting accuracy in hunting foxes”, Biol Letters 7: 355-357.