[Aunt Sally]

I'm just curious Alan.

So it's not an allotment i.e land rented out in plots to a number of tenants specifically for veg growing but a large vegetable plot on your field.

[AlaninCarlisle]

Yes, and inundated with damned moles. The weird thing is that there's barely a mole hill in the field where the horses graze, they're all concentrated in the area that I'm trying to cultivate

[Aunt Sally]

Of course they are.

1. You have tilled the ground making it easy to tunnel through.

2. You have incorporated large amounts of compost and manure into the ground.

3. Both of the above have encouraged the worms population to increase.

What do moles eat ? 

[AlaninCarlisle]

I wish it was as simple as your Eureka moment suggests Aunt Sally. However nature is rarely that straightforward or simplistic:

1 My neighbour's field which adjoins the part of our field that I've taken for my veg plot has likewise been infested with moles over an area of about half an acre for a couple of years. That infestation extends into my newly cultivated area.
2 His field has never been cultivated in living memory and like ours until I took a bit for a fruit and veg plot just contains livestock
3 According to the local mole-catcher, (Mowdy-catcher as they're called here) moles tend to colonise fallow land for a few years and then move to another area for no discernible reason. Maybe the site and its mole population get diseased or maybe they just get bored with causing a nuisance

[Aunt Sally]

... or perhaps just short of worms

[Gwiz]

Aren't Moles very territorial?
It could be that off-spring move into other areas when they become adult.
This would give the appearance of a lessening of activity in the original area as there are "less mouths to feed"?
I can't say that I've ever noticed them abandoning an area entirely unless they are are caught/killed, well, that's my observation from trapping them.

[Aunt Sally]

The are very terratorial and will fight each other.  If a mole dissapears from an area e.g. killed, another will very quickly move in and use the same tunnels, Gwiz.

[AlaninCarlisle]

Gwiz, that sounds more feasible than running out of worms for heavens sake

[Gwiz]

I was having some difficulty in the reply, Aunty, some of my post was lost.....

[Aunt Sally]

Gwiz, that sounds more feasible than running out of worms for heavens sake

Not so if you know yer moles  

The are very terratorial and will fight each other.  If a mole dissapears from an area e.g. killed, another will very quickly move in and use the same tunnels.

[Aunt Sally]

I was having some difficulty in the reply, Aunty, some of my post was lost.....

Ah.. Your full answer is spot on, except that other moles will move into disused tunnels, Gwiz.

[Gwiz]

Moles will definitely move into abandoned tunnels.
You would, wouldn't you if you were a mole....

[Aunt Sally]

Ready made home

[AlaninCarlisle]

I'll ask the owd mowdie guy when I see him. He makes a career out of the damned things so he should know

[Aunt Sally]

Then you should have no more trouble, Alan.  He will eradicate them for you