I don't know how we missed this chart on its first go-around (it was created by Eli Dourado in May 2014, using data extrapolated from a 2013 op-ed by Jon Mooallem, who spent the summer of that year keeping track of power outages caused by squirrels), but it is everything, and you deserve to know that it exists.
There's a similar problem in Japan - with crows. turns out wire clothing hangers are what crows consider to be "perfect" diameter for nest building. Just a bit unsightly if they're building a nest in a tree. In the electrical infrastructure (there are a lot of electric trains) and it's a problem.
Crows are smart, but not understand-electricity smart.