Will predators attack your swallows?
There's always danger of predation, so protecting your nesting birds is a crucial
responsibility for you as a project manager.  Finding boxes emptied of eggs or young,
or discovering discarded wings, such as the bluebird wing below, is terribly
disheartening.  You must take steps to reduce chances of this happening.  Careful
choice of project site and proper location of boxes greatly reduces risk of predators
finding your boxes, but you should also try to prevent predators from reaching any
boxes they do happen to discover.













What animals predate nesting Tree Swallows?
Raccoons, opossums, weasels, and cats will kill and eat any adults and young they can
pull out of boxes.  Raccoons are especially dangerous because if they find one box
and can predate it, they look for other boxes and may predate every box in a
project.  Most snakes can't climb poles, but a few species can, and will enter boxes
to eat eggs, young or adults trapped inside.












How can you stop a predator from reaching a box?
Make it as difficult and unpleasant as possible!  The best method is to attach a
predator guard to the pole below the box.  You should use a guard on every box
because raccoons and climbing snakes can get up even thin metal poles surprisingly
easily.  

Conical and stovepipe guards are effective, but they can be expensive to make and
very expensive to buy.  








Hardware screen guards projecting out around the entrance hole are less expensive,
but they make it difficult and time-consuming for adult swallows to access nests
when feeding nestlings.  (Note the overlarge hole and small dimensions of the box
below, obviously not a good design for Tree Swallows).








For additional information on predators and making predator guards use this link to
Nestwatcher's Resource Center.

A simple and cheap alternative uses large juice or restaurant supply cans.  The can
ends are removed and its sides are cut in strips that are bent out.  One cut goes all
the way to the end so the can fits around a pole.  The guard is supported by three
pieces of house construction "strap" secured to the pole by a hose clamp.  But be
careful handling these cans.  Their edges are sharp!








Two or three can guards fitted on a pole makes an effective predator barrier.


Why is grease sometimes put on poles?
Greasing the pole for 6-8 inches directly below a predator guard makes the barrier
even harder for predators to pass.  Pole grease also keeps ants from reaching the
nest.  







Note: If you decide to use can guards and grease, don't put them on right away.  
Most predation by mammals occurs at night.  However, male Tree Swallows almost
never roost overnight in boxes, and females usually don't until they've begun to
incubate their eggs.  If can guards or grease are added before egg-laying swallows
competing for boxes could be injured by the can edges or get their feathers fouled
by grease.  So, if you use can guards and grease, wait until your females have begun
incubating their eggs.  







        
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Learn About Birds at Tree Swallow Nest Box Projects
Predator Protection