Brush Piles Are Awesome!
I am very fortunate to live in the woods! Here is my newest brush pile, which includes lots of small branches and saplings that have fallen in windstorms, or just because they didn't receive enough natural light. The leaves are mostly oak--they are the last to come down in the autumn.
Here's another brush pile that I started in August. You can see that a small animal has already made its way into the complex network of branches and leaves. Inside a brush pile animals and birds can find all sorts of small invertebrates, larvae, rootlets, seeds, moss and all kinds of marvelous food!
I have seen juncos enter and exit from this brush pile. They spend a lot of time around these areas, foraging for insects and getting away from snow and windstorms. They also sleep in these piles at night! I know they use them for nesting places as well, because I have seen fledgling birds perching just outside this entrance hole.