So, where do rats/mice fall in the ecological spectrum?

[Bunny]

This is prompted by the earlier thread, wherein the poster said that her cat was playing with a mouse, and some folks wanted to save the poor little rodent. I got to wondering what role these vermin play in the ecological spectrum, the food chain, whatever you want to call it.

What DO they do, and why do they need to exist? Do they keep smaller critters in check? Do they carry seeds from one place to another? Or do they just carry disease?

I loathe rats and mice, and would gladly see all of them dead, quickly and painlessly, or course. So, what do you biologists say?

[mike_c]

1. they disperse seeds and repackage plant biomass...

...into a form that higher trophic levels can consume, i.e. meat. Many rodents cache seeds, but don't eat all of them before they sprout. Those are the first two things that come to mind.

on edit: Why do they need to exist? Why, to perpetuate rodent DNA, of course!

[Orsino]

2. Not a biologist, but...

Look at it another way: rodents aren't fulfilling a need so much as they are occupying an ecological niche. There is room in most ecosystems for small omnivores that reproduce quickly. If it weren't for rats and mice, frogs or bacteria would evolve to take advantage of that space. Until something comes along that does it better or reproduces faster, no one's displacing the mice.

[Inland]

3. Apparently, they fall in the same niche as humans

since it is human habitation that makes rats and mice thrive.

You might try the non-fiction book by the guy who observed rats in Manhattan for a month. I forget the name, but the reviews made it seem interesting.