Fortified Against Predators

I visited the local Audubon Sanctuary up the road from me.

The Tree Swallows have arrived, but I think they are not yet raising chicks. My guess is a visit 2 weeks from now will show a lot of bird box defense from the parents.

The bird boxes here are heavily armored against predators, with pole cans, under massive cones (often serrated), and entrance tubes on the boxes as well. A lot of poles have slinkies attached under the pole cans to discourage climbing snakes.