Nesting season is hazardous for birds, and many predators consider eggs, hatchlings, and even brooding adult birds a tempting, tasty meal. By taking steps to protect birdhouses from hungry predators, it is possible to help nesting birds raise their families in safety.
Many different predators will target birdhouses for an easy meal. The most common culprits include:
In addition to these common birdhouse predators, larger birds will also often threaten other nesting birds. Jays, grackles, crows, starlings, magpies, and other large birds are partially avivorous and will happily take advantage of eggs and chicks as an easy food source if they can get into birdhouses or nests.
Make Birdhouses Safe From Predators
While it is not possible to make many modifications to create safer nesting areas for birds that nest in trees and shrubs, cavity-nesting birds can be helped with a wide range of tactics. Birds that nest in birdhouses are subject to the safety of that house, and by making houses more resistant to predators, parents and their chicks are more protected.
Techniques to make birdhouses more predator-resistant include:
- Hole restrictors: Many predators will claw or chew on birdhouse entrance holes to enlarge the holes for easier access. A hole restrictor is a metal plate fastened over the existing entrance hole to prevent that enlargement, thereby permitting only birds of the appropriate size to enter. This also helps prevent larger birds from using the house, either as predators or to usurp the nesting site. Hole restrictors are also a great way to adjust birdhouses to have the proper entrance hole size for only the desired bird species.
- Tube entrances: Another way to make it harder for predators to reach inside a birdhouse is with an elongated tube or tunnel entrance. Many cavity-nesting bird species don't mind a longer entrance, but predators lack the extra reach necessary to stretch through the tube and endanger the birds inside. A simple piece of pipe 2-3 inches (5-8 cm) long attached over the entrance hole can work, and birdhouse manufacturers also offer tube entrances fashioned like hollow branches for aesthetic appeal and camouflage.
- Roof size: Large predators such as squirrels, cats, and raccoons may sit on a birdhouse roof and reach inside to attack the nesting birds or chicks. A longer roof that extends 5-6 inches in front of the house and 2-3 inches on either side provides a built-in baffle to limit predators' reach and prevent them from accessing the entrance. Longer, wider roofs also provide better shade and rain shelter for the entrance hole to keep the house cooler, drier, and more comfortable for nesting birds.
- Baffles: Predators can easily access birdhouses by climbing up poles or approaching down trees from above the house. Installing metal baffles both above and below the house as necessary will help minimize predator intrusions. Metal baffles are more difficult for predators to climb, and attaching a birdhouse to a metal pole will provide even more protection. If the tree or pole is too wide for a baffle, a large, broadsheet of smooth metal wrapped around the trunk will serve the same purpose to keep predators from climbing.
- Removing perches: A perch on a birdhouse is more than just decorative, it is dangerous. Birds do not need a perch to move in and out of the house, but a predator will use the perch as a convenient handhold to steady themselves when they raid the nest. By removing any perches or similar ornaments that predators could cling to, you make it more difficult for them to access birds or eggs inside the house.
- Safe mounting: Properly mounting a birdhouse not only makes the house more attractive to nesting birds but also helps safeguard the house from predators. A properly mounted house will be at least 10-12 feet above the ground and away from any buildings, trees, or shrubs predators can use to jump onto the house. Similarly, avoid placing a house near an arbor, fence, or trellis that predators can use to climb closer to the house, and avoid locations with heavy shrubbery that can conceal predators.
- Predator repellants: Different products can discourage predators from approaching a birdhouse. Hot pepper sprays or other products with strong smells and tastes can be applied around birdhouse entrances to deter predators. For better protection, also use these products on poles, nearby plants, or the roof of the house, wherever predators may come close to the house. Songbirds do not have strong senses of smell or taste and will not be put off by the products, but predators will be. Take care, however, not to spray any materials inside the house where they may contaminate vulnerable hatchlings.
While there are many ways to make a birdhouse safer, making the entire area less welcoming to predators can help safeguard nesting birds as well. Easy options include:
- Trim shrubbery to remove extra cover that can conceal hunting predators.
- Choose landscaping with sharp edges, thorns, or strong odors to discourage predators.
- Remove foods for predators, such as leftover birdseed or windfall fruits, so they do not regularly feed nearby.
- Cover compost piles and ensure trash is disposed of properly so predators are not attracted to easy food sources.
- Take steps to discourage feral cats and always keep pet cats indoors, away from nesting birds.
- Avoid handling the house to not leave behind a scent that can attract predators.
- Winterize birdhouses so small predators don't claim the house each winter for their own use.
It can be disheartening to see a predator invade a birdhouse and tear a feathered family apart, either figuratively or literally. By taking steps to make birdhouses safe from predators, however, it is possible to minimize the risks birds face when they take up residence.