Saratoga Springs, New York

The Backyard Watcher:

Stovepipe Baffles -- Keeping Predators Honest


by Julie Zickefoose
Baffled nest box
I've just come back from checking a friend's bluebird trail, a string of next boxes that he's mounted on low fenceposts and telephone poles.  I've checked over a dozen boxes, in high nesting season, and only one has live baby bluebirds inside.  All the others bear the traces of bluebird nesting attempts, all but two of them unsuccessful.  Broken eggshells, nests cleaned by black rat snakes; ripped-out nests, the mark of raccoons; even a dead female bluebird, killed on her nest by a mouse.

By contrast, my boxes hold nest after nest of eggs and young, with none of the disturbing traces of predation.  The difference between the two trails?  My boxes are baffled.  Baffles mean the difference between nesting success and failure; feeders that feed birds and those that feed squirrels and raccoons.

A baffle is a device that is mounted on a metal support pole, which deters climbing mammalian and reptilian predators.  It can protect a nest box or a feeder.  Baffles are different from predator guards, small devices made of wire or plastic that are mounted on the entrance hole of a nest box, and which are meant to keep a raccoon or cat from reaching deep inside the nest box.  A properly designed and mounted baffle is the only effective means of safeguarding a nest box or feeder.

Having fed birds since the 1960s, and having maintained bluebird boxes since 1983, I've tried and tested a lot of different baffle designs.  Perhaps the most effective was a homemade sheet metal cone, 30 inches in diameter at the bottom.  It was also the most dangerous, with its great weight and sharp edges, and it was given to self-destruction in high winds.  For ease of handling and efficacy, I keep coming back to the stovepipe baffle.

A stovepipe baffle, constructed of metal, is mounted so that it wobbles a little.  This motion and its hard-to-grip surface prevent most climbing mammals and reptiles from gaining purchase on it.  Baffles are most effective when they are installed the moment the nest box or feeder is mounted.  This keeps your local raccoons and rat snakes "honest."  An honest predator is one that has never climbed a pole and gained a reward of bird eggs, seed, or suet.  Like a locked front door, baffles keep honest predators out.  They must be used with metal poles of a diameter that's compatible with the baffle.  Metal poles alone are not enough to stop predators.  And, contrary to popular belief, greasing a pole often gives predators a better foothold, as soon as the grease hardens and begins to oxidize.

A baffle that will stop a raccoon is a pretty formidable piece of equipment.  Ideally, it should measure 6 inches or more in diameter, and be at least 24 inches long.  Squirrels may be foiled by smaller baffles, but where both mammals occur, it's best to err on the side of over-baffling.  It's vital to stop climbing animals before they learn that your nest boxes or feeders hold a food reward.  And consistency matters; it won't do much good to baffle one nest box if the neighboring box is left unprotected.  Sooner or later, predators will figure out how to raid the unprotected box, and then the baffle's effectiveness is compromised, because the predators now know that a reward awaits the persistent.

Before you erect a nest box or new feeder, purchase a metal pole and a good metal stovepipe baffle.  It'll save you time and heartache, and you'll have the pleasure of knowing that nesting birds are safe in the lodging you provide.