These helpers are often daughters from previous years, but they could also be the main vixen’s sisters or even her mother once she has passed breeding age. About one in three fox families has one or more non-breeding vixen helping out, and there’s usually a hierarchy so that only the alpha female gives birth. Studies have shown that helpers don’t necessarily increase the cubs’ chances of survival but they do take the pressure off the parents, which don’t have to work so hard to feed the cubs.
So what’s in it for the helpers, when they could be raising cubs of their own? It may be a case of ‘kin selection’, a strategy that means sometimes it’s better to help raise a relative’s young even at a cost to the individual. When the time comes for a fully-grown cub to disperse, it has to weigh up the costs and benefits of staying against the risks of leaving home. If it stays, the cub may not breed for a year or two but it might inherit the territory. By leaving home the cub may have young of its own by next spring but it must find its own territory first. Mortality can be high for dispersing cubs so it is a difficult choice for them to make.
Choosing to stay at home doesn’t always mean that a fox won’t get the chance to breed, though. In 2012, Springwatch followed a fox family that had a mammoth litter of eleven cubs living under a garden shed in Potter’s Bar. Most litters only have four to six cubs so this was unusual. After watching the family closely for several weeks it became apparent that there were actually two adult females, one dominant and one subordinate, and both appeared to suckle the young. It seems that both vixens were mothers and they had pooled their litters to raise them cooperatively.
Dogged by a Bad Smell
Just a quickie, why do dogs love to roll around in fox poo? What is the attraction? Jackie
Members of the canine family, such as wolves, dogs and foxes, have a very acute sense of smell. Humans are primarily visual creatures while a canine’s world is ruled by scent. Dogs and their wild relatives can pick out the faintest scents using their wet noses and millions of olfactory receptors. A large proportion of a dog’s brain is devoted to processing all this olfactory information and their sense of smell may be several million times more sensitive than ours. In the wild they would use this skill to track down prey or other members of their species, but we humans have exploited the dog’s nose for a wide variety of tasks, from finding truffles and recovering shot game birds to detecting explosives, illegal drugs and missing people.
Scent is vital in fox communication too. Foxes often mark their territory by defecating in conspicuous places, such as on top of molehills, at the junction of paths or on tussocks of grass. It’s thought that a fox’s faeces provides clues to the animal’s sex, fertility, health and status. Both fox urine and faeces have a distinctive, musky smell that even our weak human noses can easily detect!
Why then, if dogs have such a sensitive nose, would they choose to roll in something as stinky as fox poo? It’s thought to be a relic of their wolf ancestors and may have several purposes. Wolves roll in something pungent like a rotting carcass or another species’ droppings as a form of olfactory camouflage. They first rub their cheek against the object then slide against it, covering themselves in a foreign scent. This may disguise the wolf’s own smell so that it isn’t detected by prey when attempting to hunt. Scent rolling may also enable a wolf to bring back any novel scent it finds and share it with the rest of the pack. When the wolf returns it is sniffed and licked by other wolves that then pick up the scent. Another theory is that certain scents may act like perfume or aftershave and make the wolf more attractive to others.
Regardless of the motive, dogs that have rolled in fox poo certainly aren’t more attractive to humans! Not only is the smell offensive, it’s also unhygienic. Fox droppings may carry diseases and parasites like tapeworms and roundworms, so it goes without saying that if you wash the fox poo off your dog make sure you wash your hands very thoroughly afterwards.
The Sweet Smell of Success
Do starlings like scented nests? Earlier this spring I saw a couple of starlings pulling bits out of my lavender bush and flying off with them, at about the time that they were nesting. I can only assume they like the smell. By the way, I now have approximately 50 starlings – adults and young – feeding in my small town garden. Sue
Male starlings have been known to adorn their nest with yarrow, parsley and hawthorn as well as lavender. They might be attempting to court a female by saying it with flowers but it seems that scent is more important than beauty. Several species of birds appear to have a penchant for aromatherapy, not just starlings, and they continue to bring scented plants to the nest once their chicks have hatched.
On Springwatch, cameras inside a blue tit nest showed the adults bringing in mint – they didn’t feed it to the chicks but placed it around the nest. At first, biologists thought birds might be using aromatic plants to deter parasites such as lice, maggots and ticks, much like we use mothballs. In fact, French biologists have discovered that plants such as mint, lavender and the curry plant are used for their antibacterial properties. Blue tit chicks raised in nests lined with these aromatic plants have fewer bacteria on their skin. This may allow them to put effort into their growth rather than strengthening their immune system. Chicks surrounded by scented leaves appear to grow more quickly and thus have a better chance of survival. Individual blue tits have particular preferences for which plant they collect – some prefer mint while others always collect lavender, even when both herbs are available.
A similar study on starlings showed that the air inside nests lined with fresh herbs is full of volatile compounds – smelly chemicals from the plants’ essential oils. They include limonene (citrus-like), myrcene (from thyme) and phellandrene (peppery-minty, like eucalyptus). The aromatic plants were shown to repel mosquitoes as well as inhibit the growth of bacteria; this is advantageous because blood-sucking insects aren’t just an annoyance, they can spread diseases to the chicks.
City birds have adapted to their surroundings by using cigarette butts instead of plants to scent their nests. Research in Mexico showed that by lining their nests with the nicotine-infused filters from smoked cigarettes, house sparrows and finches reduced the number of mites and other parasites. Nicotine is a natural insect repellent produced by the tobacco plant as a defence against herbivores, so it’s not a surprise that it deters parasites too. Over the years, Springwatch has received many photos of blue tits and other birds nesting in cigarette butt bins, so it seems that British birds have learned the same trick.
Hungry Herons
We recently saw a heron catch a wounded bird. It decapitated it then took it to the water’s edge and ate it. I thought they were fish eaters, or will they eat other things if it’s an easy catch? Lesley
How common is it for herons to ‘nick’ moorhen chicks? This weekend I saw a heron bully two adult moorhens until they moved from the nest and it then nicked a chick and flew off! Tessie B
Herons aren’t fussy eaters and have a very varied diet which includes small mammals, insects, little birds and amphibians as well as fish. They will catch birds up to the size of a water rail, so moorhen chicks are just a small snack.
Despite their long neck, herons have the same number of vertebrae as other birds but the bones are specially configured so that herons can bend their neck into an ‘S’ shape, allowing them to strike quickly. Usually, herons rely on stealth for hunting, waiting motionless before launching their long, sharp beak to snatch a fish or other