There are two sides to every bird feeder — the bird side and the mammal side.

Like the song says about love and marriage, you can't have one without the other.

Our bird feeders, all hanging-tube style, can't be reached by any mammal but me, stretching.

In the back of our yard, four feeders in one set hang from arms atop a 12-foot piece of 1-inch pipe driven into the ground. The set of two on our deck hangs from a shepherd's hook with a round metal base.

In both cases the raccoons quickly learned to grasp the poles and shake them like crazy until all of the seeds fell out. Raccoons are clever.

In the backyard I firmed the ground around the pipe with stone, making shaking difficult. Super raccoons might succeed.

The deck feeders are taken in each night at dusk, the only certain way to thwart the bandits. We hung a set of sleigh bells with the feeders, hoping thievery would raise an alarm, perhaps even frighten the raccoons.

The alarm was raised, but it required response, otherwise why bother. I quickly tired of response.

Chipmunks and red squirrels are tolerated as deck vacuums.

There would be no seeds for them if birds were not so picky.

White-breasted nuthatches are the worst. They snatch sunflower seeds from the feeders, flinging the smaller aside, keeping the larger. I assume they are selecting for size.

Blue jays will do the same with peanuts in the shell, testing this peanut or that, keeping those judged heaviest. Citizen science, loading peanut shells with BB pellets, has proved this. The heaviest shells are preferred.

The nuthatches are eyeballing the seeds, no need to weigh things. They seem to distinguish centimeter differences in milliseconds.

Gray squirrels can't climb the narrow, smooth feeder posts, which is why the posts are narrow and smooth. Squirrels don't discourage easily, but it can be done.

I have live-trapped squirrels, but that, too, requires a response of which I tire. I've been told that the squirrels know where they live, and return. I've been tempted to mark tails with white paint to see if that's true. Again, more effort than benefit.

I've live-trapped raccoons, too, once — not something I recommend. Raccoons are ill-tempered.

Shrews, voles, mice — all are welcome. They are interesting creatures, almost unknown because of nocturnal schedules and timidity. I'd be a mammal watcher if mammals were easier to watch.

We've seen deer, of course, but fewer in the past couple of years, and never interested in feeders. Perhaps we retire too early, arise too late. Coyotes are here, singing the soprano parts out there in the dark, rarely seen. They are hunting raccoons, I hope.

Rabbits, yes, and muskrats, both cute without cost at the feeder.

Once a beaver spent two days in our shallow pond, eating willow shoots, never bird food. We decided it was a beginner beaver, pushed out of the lodge by its parents.

The youngster was learning life one small pond at a time. It had no choice. Beaver parents lack a basement to which the youngster could return.

Read Jim Williams' birding blog at startribune.com/wingnut.