This was an unexpectedly fascinating read. This blew my mind:

> Rats are responsible for about half of all bird and reptile extinctions on islands, according to Gregg Howald of the group Island Conservation.

I live in the LES of NYC, and will routinely see 50+ rats in a 10 block span. They have massive burrows through a local park, with ample opportunity to live and breed, and a constant supply of trash and food (sometimes left "for the birds.")

One small benefit is that they prove a consistent supply of food for the local park's hawks, which can regularly be seen feasting on them.

Here's a cool video of hunting dogs attacking a rat burrow: https://www.youtube.com/watch?v=NxQksEF2uso