The House Sparrow (Passer domesticus) is a non-native, invasive species in North America that competes aggressively with native cavity-nesting birds. This competition often leads to the displacement, injury, or death of desirable native species, such as bluebirds, swallows, and chickadees. Selective control is necessary to protect local bird populations, but it requires specific, targeted methods designed to exclude House Sparrows (HOSP) without harming protected native birds. Achieving this balance involves modifying food sources, protecting nesting sites, and altering the general habitat to make it less appealing to this highly adaptable invader.
Selective Feeding Strategies
House Sparrows are generalist eaters, but they demonstrate a strong preference for certain low-cost seeds often found in mixed birdseed blends. These preferred foods include cracked corn, millet, milo, and wheat, making these blends a primary attractant for House Sparrows. Eliminating these filler seeds from your feeding regimen is the simplest first step in selective feeding.
Instead, switch to foods that House Sparrows find less palatable or more difficult to access, such as safflower seed or Nyjer (thistle) seed. Black oil sunflower seeds are widely enjoyed by native birds, but switching to striped sunflower seeds can also help, as the harder, thicker shells are more challenging for the House Sparrow’s beak to crack compared to the thinner shells of the black oil variety.
House Sparrows prefer stable feeding platforms, such as large hopper feeders or platform feeders, where they can perch comfortably. Switching to tube feeders with very short perches, ideally less than 5/8 of an inch, makes it difficult for House Sparrows to feed while still allowing smaller native birds like chickadees and finches to cling and eat. Weight-activated feeders are highly effective, as the collective weight of multiple House Sparrows feeding at once triggers the ports to close, denying access to the food.
Protecting Nest Sites
House Sparrows are notorious for aggressively taking over existing nest boxes intended for native species, often building bulky nests that quickly fill the cavity. A specific engineering solution is the use of entrance hole restrictors on nest boxes, which limits the size of the opening. For Eastern Bluebirds, the standard hole size is 1 1/2 inches, which House Sparrows can easily enter.
Reducing the entrance hole size to 1 1/8 inches to 1 1/4 inches can exclude the House Sparrow while still allowing smaller native cavity nesters, such as chickadees, to enter. Another method involves using a slot-style entrance rather than a round hole; studies suggest that bluebirds will readily use a 4-inch long by 1.25-inch high rectangular slot, a design that House Sparrows tend to avoid.
Routine monitoring of all nest boxes is necessary to ensure any House Sparrow nesting material is ethically and humanely removed before eggs are laid. If a House Sparrow nest is found, it should be removed immediately, as their nests, eggs, and young are not protected by federal law. The aggressive nature of these birds means they will often attempt to re-nest, requiring consistent vigilance from the monitor. Placing nest boxes away from human dwellings, where House Sparrows prefer to forage and breed, can also reduce competition for native birds.
Habitat Modification and Exclusion
Beyond specific feeding and nesting sites, broader habitat modification can discourage House Sparrows from settling on the property. House Sparrows frequently seek out dense, protected spaces near human structures for roosting and nesting. This includes dense ivy, thick ornamental shrubbery, and structural crevices like vents, eaves, and gaps under decks.
Trimming back excessive vines or dense, unkempt shrubbery eliminates these sheltered roosting locations, reducing the bird’s sense of security. To prevent nesting in structural voids, physical exclusion methods like installing bird netting or wire mesh are effective. Netting should have a mesh size small enough to physically block the birds, typically 3/4 inch mesh, and must be installed tautly to prevent birds from becoming entangled.
Sealing all holes, cracks, and gaps in exterior walls, especially near the roofline, is a proactive measure against House Sparrow nesting. Because House Sparrows are non-migratory and remain near their breeding sites year-round, these exclusion methods create a long-term deterrent. The goal is to make the entire environment less suitable for House Sparrows while leaving areas that appeal to native birds, such as open spaces and native plant cover.
Legal Status and Humane Practices
The House Sparrow is one of a few common species in the United States that is not protected under the Migratory Bird Treaty Act (MBTA). The MBTA protects all native migratory birds and their parts, nests, and eggs, but the House Sparrow is an invasive, non-native species, meaning that control methods, including nest and egg destruction, are permissible. This legal status allows for aggressive management of their population to protect native birds.
Before implementing any control method, it is necessary to correctly identify the bird as a House Sparrow. Harming or disturbing any native bird, its nest, or its eggs is a serious federal offense under the MBTA, carrying significant penalties. If there is any doubt about the species, no control action should be taken.
Humane practices should always be the priority, with non-lethal methods like habitat modification and selective feeding implemented first. Only after exhausting these exclusionary techniques should more intrusive control methods be considered. Positive identification ensures that control efforts are directed solely at the invasive species, maintaining an ethical and legal approach to backyard bird management.