Will predators attack your swallows?
There's always danger of predation, so protecting your nesting birds is a crucial
responsibility for you as a nest box project manager. Finding boxes emptied of eggs
or young, or discovering discarded wings, legs and clumps of feathers is terribly
disheartening. Please take steps to reduce chances of predation. Careful choice of
project site and proper location of boxes will limit 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, cats and opossums will kill and eat any adults and young they can pull
out of boxes.
- Weasels can actually enter most boxes they can climb to. Photo below of a
Short-tailed Weasel exiting a predated swallow box by Barbara Russell.
- 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 predators from reaching boxes?
- 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, as the photo below taken
during experiments conducted by bluebird expert Keith Kridler demonstrates.
- Conical and Stovepipe Guards (see below) are somewhat effective, but they
can be expensive to make and very expensive to buy.
- Hardware Screen Guards that project 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).
- Can and Grease Guard: A simple and cheap guard may be made using large
juice or restaurant supply cans. A can's 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 will
fit around a pole.
- The guard is supported by three pieces of house construction "hanger strap"
secured to the pole by a hose clamp (below left).
- Two or three cans are then fitted on the pole. Be careful handling the cans;
their edges may be sharp!
- Adding a band of engine grease 6-8 inches wide directly below the predator
guard makes the barrier even harder for predators to pass (see below). This
grease also discourages ants from reaching nests.
- 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
- So, if you use can guards and grease, wait until your females have begun
incubating their eggs.
Learn About Birds at Tree Swallow Nest Box Projects
|Creating Projects, Tree Swallow Basics, Finding a Good Site, Building Boxes,
Box Location, Pole Options, Mounting Boxes, Nest Box Grids, Predator Protection,
Bluebird Competition, Martin Competition, House Wren Damage, House Sparrow Damage