29th March 23013
Sunrise 05.51 am Sunset: 06.38 pm
I have mentioned in previous posts that foxes are not dullards. They are sometimes called vermin, but are not classified as vermin in the UK. The fox is a primary predator that eats vermin; in particular, it helps control the population of rats, pigeons and other small marsh animals. Foxes are extremely important to the delicate Reserve ecology. Without them, the marsh, and the surrounding houses and the factories might have serious rat infestation problems. I live across the road from the marsh, and I have never seen a rat anywhere near my house. The foxes are not the only marsh predator eating the rats, but they are the main one.
To my knowledge, the north marsh vixen has four dens, and I checked each one late this afternoon.
The vixen reworks the birthing den at the beginning a new cubbing season. The birthing chamber is small: just large enough for her and the cubs. The entrance is via last year’s den. A five metre long tunnel running north to south, leads to a 300 mm diameter by 600 mm birthing chamber, buried roughly 600 mm underground. One metre back down the tunnel from the birthing chamber is a 125 mm diameter vertical ventilation shaft (see the image below).
When the cubs have grown too big for the birthing den, the vixen will move them to the summer den. The summer den is basically a large cave dug into the side of a bramble covered knoll, with an escape tunnel to the rear. There is a flat grass area outside the den entrance, where the cubs can play and sun themselves on warm summer evenings. The vixen and the dog will leave food close to the entrance.
If the birthing den is compromised, or for some other reason, the vixen might need to move the cubs to a safer place. There is a third and slightly larger den they can use, again dug into a dry bank, not too far away, with an entrance tunnel driven 600 mm into a vertical bank, before turning 90 degrees into a living chamber.
There is a 4th and really well hidden den close by also; I guess this den was vacated during a mange outbreak. The reason I say this is that the summer den, and the third den are clean and used regularly; the fourth den isn’t. Outside of the cubbing season, I think the dog uses the summer den, and the vixen the smaller one, during adverse weather.
Under normal conditions, though, the foxes live above ground. They use lie-ups and cubby holes around the marsh; these might be in brash piles, under fallen trees, in hollow tree trunks, or in oddly shaped living trees, as in the image below. These above ground lie-ups are situated on the north marsh; I think near hunting hot-spots. I don’t think the foxes use the same one too often; they move around regularly, and I wouldn’t be at all surprised if the muntjac deer uses them also.
The more I watch the foxes, the more I understand the structure in their lives, and the more I appreciate their ecological value. However, I could say similar things about the badgers, and the Shetland cattle, but neither of these will have a significant impact on the rat population. All the marsh animals have their part to play in the success of the Reserve, as long as they exist in sustainable numbers.