We live in an old farm-workers cottage. The farm surrounding us was sold 2y ago, and moved from intensive arable management to organic herbal ley with a focus on increasing biodiversity and soil health. We have seen a significant increase in rodents this year.

My neighbour and I disagree on the likely cause of this increase. IMO, it is due to the change in management of the hundreds of acres surrounding us (which I fully endorse and welcome - the increase in biodiversity that is, less so the mice scrabbling in my roof!). We've all noticed increased insect populations since the herbal ley was sown (it's mob grazed by cows). We also have a woodland, farm buildings with straw and silage storage, pond and derelict stables nearby (although this hasn't changed recently). In my neighbour's opinion, it is all down to my small flock of chickens that are across the road from our houses (rodent-proof feeders, mostly free ranging so they barely eat any pellets, food picked up at dusk, rodent-proof feed bins, everything off the floor so nowhere for mice to live under, run has thick rodent-proof mesh on floor and sides, trail cams and traps monitor the area, my farm cats regularly catch/eat mice etc, been there for >5y). I know poultry = rodents, but given the other sources of rodent food/shelter, I feel the impact my chickens have is going to be small in comparison, and anyway is probably less than the opposite impact my farm cats have on rodent numbers.

Are there any really clear-cut studies comparing biodiversity between herbal ley and intensive arable (specifically rodent numbers), that a lay person could understand? Or publications by bodies like Wildlife Trusts? Any reliable sources of information that could help settle this debate? Happy to be proved wrong, but I'm still not getting rid of my chickens ;-P

If much of Florida fauna dies because they are uncompetitive vis-a-vis the burmese python, isn't that natural selection?