The private lives of foxes

Mike Powell heralds the start of a busy time for foxers with some insights into the fox mating season

By the time this article appears, the fox mating season will at last be under way. I say “at last”, as for many who seek the fox for sport, as a necessity or as a business the mating season is, together with post harvest fields the best time of year to reduce numbers before the new crop of cubs appears. In foxing circles I suspect nothing gives rise to more comment, apart from how to deal with cubs, than the mating season of the fox. Every year reports come in of foxes mating any time from late August onwards. I don’t profess to be an authority on the mating habits of the fox, but having spent a lifetime that has always been involved with foxes, I can only report on what I have learned over the years.

So what of these early signs of mating reports? From August onwards the current year cubs are just starting out on their own, but like most young creatures still like to keep in touch with the parents and also their siblings. Many of the calls heard during August and September are being made by the family still keeping in touch, and not mating calls. Foxes make many different sounds, but perhaps the best known are the staccato three short barks and the ‘scream’. Both sexes make these sounds, as do well-grown cubs, and the three short bark call is the one that I am sure is the ‘checking out where you are’ call. The very same sound can be heard after the turn of the year, but careful listening will detect a certain urgency to it that is not there earlier in the year.

A litter of five cubs. Note the rabbits on the lookout

The other common occurrence is that people report seeing cubs at odd times of the year. In fact, only recently I had a call from a local poultry keeper to say there were a couple of cubs bothering his chickens, could I sort it out? Bearing in mind this was late October I was a bit sceptical to say the least, a couple of first dark visits had one of the culprits down and out, and a quick inspection showed it to be a really small vixen in fairly poor condition, but by her teeth was at least a couple of years old. There really are some very small foxes about which, if people have been seeing only large ones, would certainly give the impression that they were cubs. How many times do you hear people say, “I saw a big dog fox” or “a little vixen”? Those who have dealt with a lot of foxes will be aware that you can in fact get really small dogs and really large vixens, although it would be fair to say that, as in most mammals the male is generally larger than the female.

Despite this, there have been substantiated records of cubs being found at odd times of year, but they are rare in this country. Possibly the obvious changes in climate may well in due course change things, but evolutionary changes take a considerable time.

The mature dog fox’s body starts preparing for mating as early as August when a slow build-up of sperm starts, following a cessation of sperm production from spring through to late summer. During this ‘lay off’ period, the sperm deteriorates to such a state that it is no longer viable. By December the testes have increased substantially in size, and the dog fox is ready for action. All he needs now is a willing vixen, and this is where his troubles begin.

It won’t be too long before earths are occupied

Vixens come into season once a year, although in captivity it has been known for an extremely low percentage (around one per cent) to come into season twice. In this country vixens can on rare occasions come into season in late October, oestrus being triggered by the shortening days. However, the vast majority come into season rather later from December onwards. This condition lasts for around three weeks, during which time she is clearly attractive to the dog foxes. However, critically there is only a three-day period within that time when successful mating can take place. It is during this three-week period that dogs chasing vixens can be seen.

As with all mammals, particularly predators, the timing of the birth of their young is timed to coincide with a good food supply, so with a gestation period of 52 days matings that take place in mid to late January would mean that by the time the cubs were weaned there would be young rabbits and other sources of food becoming available.

The breeding arrangements of the fox are complex, and even after a considerable amount of study there are several matters that are still largely unknown. As with all things involving wild animals there will always be anomalies, and while I personally after many years involvement with foxes have only ever seen one litter of young cubs at a really odd time – and that was this year in late August – I have no doubt it does occur, but is a rarity. I would be most interested to hear from any readers who have evidence of early or late cubs.

Taking out the alpha vixen can possibly lead to more subordinate vixens breeding

When I was keepering I was always pleased to see vixens taken out before producing their cubs, as it’s a much easier way of keeping on top of the fox population, and prevents a lot of stock damage later on when the adults are feeding their litters.

While on the subject of cubs, litter sizes have always intrigued me. The largest number of cubs I have seen in one litter is five. I believe that in this country the largest litter that is likely to occur is eight. Occasionally larger numbers of cubs are mentioned, but these are almost certainly the result of litters from more than one vixen. I once saw ten cubs playing together in a field, but after a while two vixens could be seen in attendance.

Local fox numbers, particularly these days when so many people are shooting, appear to remain reasonably stable. On my own patch, numbers over the years have remained pretty much the same. One thing I have noticed, though, is that there appears to me to be more litters than I remembered years ago. Checking research on cub production reveals the possible reason for this. If left alone fox cub production is controlled by the dominant female, as it is she who by various means prevents her subordinates from mating. In fact, within family groups, which can be quite large, only one or two vixens may produce litters in a year.

However, when we come along and take out a number of vixens then the order of things varies. For a start, should the alpha female be killed her dominance over the other vixens disappears, and they are released from her control and seek out a mate. Territory also comes into the equation. Foxes’ lives are very much controlled by territorial boundaries, and when foxes are killed it opens up areas that previously foxes would be wary of travelling in. This again allows younger vixens that would otherwise be restrained from mating free rein to get out and find a mate.

A couple of vixens dealt with now saves a lot of trouble later

Nature abhors a vacuum, and I have noticed that in the years when myxi hit the rabbit population badly, the following year saw higher proportion of does than normal. So it appears to be with the fox, the harder you cull, the more vixens are likely to have litters. Clearly there is a point where if very high numbers are culled then the overall balance could be so disrupted and reduced that the local population could collapse altogether. However, neighbouring foxes will now have this area at their disposal, and will rapidly repopulate it. The old saying along the lines of ‘shoot one fox and two more will move in’ has much to substantiate it. If, for instance, I was to shoot every fox within the boundaries of my village (highly unlikely), every fox in the land that borders those boundaries would be free to come in, so there would be every likelihood that I could, for a while, end up with more foxes than ever. I have seen this so often when I have taken out several troublesome foxes, and for a while seen very few, then suddenly they are back in numbers for a while which then, as new territories are sorted out settle back to pretty much what they were before. Of course, should your neighbours have a strong fox control setup in operation there will be few foxes to replenish your stock. This is when you hear people stating they have no or very few foxes left to shoot.

It is interesting to note that although so many spend so much time endeavouring to control foxes, there is much about their complex family lives that to most people is a complete mystery.

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