Since Bluebirds live in the wild and there are lots of predators you can minimize the risks by following the precautions listed below.

Ants: Fire ants are common in South Carolina and will attack baby Bluebirds.

Frequency is low. To avoid this problem carefully examine the ground around your box in a 20-foot circle for holes in the dirt and especially half-moon piles of sand each time you monitor the box. If you see any ant activity treat it with an Ant killer such as Amdro.  You can also apply bearing/axle grease to a 6-inch section of the pole, preferably under the predator guard.

Crows: These incredibly intelligent birds have been known to stand on the top of the box and reach down thru the opening to remove the young.

Frequency is low. Some Bluebirds build very tall nests which allow the crow to rob the nest if the young are near the entrance hole. As you monitor your nestbox check to see if the top of the nest is very near the entrance hole. If so, gently remove the lower section of the nesting material to reduce the height of the nest and leave 3-4 inches of nest material.

Feral Cats: Feral cats may be a problem for birds if a predator shield is not installed on a nestbox.

Frequency is low. You can prevent this problem by installing a predator shield on your metal pole and ensuring the box is not within 10 feet of a fence/tree.

Flying Squirrels: They are more of a nuisance than a predator as they do not usually kill the babies but instead take over the box for their own brood.

Frequency depends on the population of flying squirrels in the area. If they are in the area, the frequency can be high.

Flying squirrels are known to glide for 50 feet.  By moving your box at least 30 feet from the closest tree branch most problems can be avoided.  If the problem persists submit a Volunteer/Contact form and one of our board members will respond.

Gray Squirrels: They are more of a nuisance than a predator as they do not actively hunt the baby birds but instead take over the box for their own nest. Gray squirrels are normally too big to enter a Bluebird nestbox with a 1.5-inch diameter hole.  The squirrel may chew the entrance hole to open it wider to allow entrance into the nestbox.

Frequency depends on the population of squirrels in the area. If they are in the area, the frequency may be high. This is easily prevented by moving the box 10 feet from any tree branches and installing a predator shield on your metal pole. In addition, place a metal guard around the entrance to prevent a squirrel from chewing on the wood around the hole.

Hawks: Cooper’s and Sharp-shinned hawks in addition to Kestrels attack and kill birds.

Frequency-moderate. There is nothing you can do to prevent this from occurring.

House Sparrows, English: They are non-native and considered to be an invasive species. They are known to kill the mother/babies in the box and break the eggs.  If you open the box and find blue feathers and broken eggs, they are the most likely suspect.

Frequency is area dependent. See NABS Factsheet House Sparrows under Resources Tab for nest/egg identification and possible mitigating actions. These birds are non-native and are not federally protected. The nest and eggs can be discarded but it is preferable to apply a coating of oil to the eggs or shake the eggs and place them back in the nest. The mom will continue to incubate and not attack another nest but the eggs will not hatch.

Mites: Mites are introduced into the nestbox when the nest becomes dirty from fecal matter or spillage of food materials. They can cause irritation and feather loss.

Frequency is common. Apply a layer of diatomaceous earth (a white powdery substance commonly called DE) on the floor of the nestbox prior to nesting or squirt some into the nesting materials using a plastic squeeze bottle. Clean out old nesting material usually laden with fecal matter from previous broods.

Raccoons: These critters are highly intelligent and strong. They can rip apart a nestbox and eat all moms/babies/eggs found. They normally reach into a nestbox and grab whatever they find including eggs and young or adult birds. If you find nesting material hanging out of the nestbox, you can be certain that the nest was robbed by a raccoon or cat.

Frequency is low. You can prevent this problem by installing a predator shield on your metal pole and ensuring the box is not within 5 feet of a fence/tree. You can also install a “Noel Nest Guard” around the entrance hole of the nestbox.

Snakes: The black rat snake is the main predator in South Carolina but Corn and Black snakes also participate. Of our predators, the rat snake is the most common, usually responsible for more than 80% of our predator losses. In our experience of monitoring thousands of nestboxes, we have not found a venomous snake in a nestbox in South Carolina.

Frequency is high. There is no silver bullet to this problem but the most effective weapon is the predator shield and not throwing the old nest on the ground near the box. Snakes have incredible memories and may return. If a snake robs your nestbox, the nesting material will remain undisturbed.

Starlings: They can be an aggressive nestbox stealer.

Frequency is none if you use an SCBS-approved nestbox.  They are prevented by restricting the hole in the nestbox to 1 ½ inches in diameter.

Wasps/Bees:  When they take over the nestbox the Bluebirds will abandon the box and babies.

Frequency is common. When approaching the nestbox, stop 5 feet away, listen, and observe. They build nests up under the predator shield and/or inside the nestbox. Taking EXTREME caution, you can use one of the commercial wasp sprays that allow you to stand 10 feet away. If inside the box, shoot the spray thru the entry hole. Once the wasps/bees are dead, they can be removed. If you have an allergy to wasps or bees, make sure you carry the appropriate medicine with you.

Ticks: Ticks are introduced into the nestbox via the parents or from nesting materials. They can cause irritation and death of the young as they suck blood from the host.

Frequency is uncommon.  Visually inspect the young before feathers develop to see if any are apparent. Apply a layer of diatomaceous earth (a white powdery substance commonly called DE) on the floor of the nestbox prior to nesting or squirt some into the nesting materials using a plastic ketchup squeeze bottle. If ticks are found, gently remove the young from the nest and remove/pull the tick from the youngster.