The resourceful method of using a tuna can and a nail offers a simple, inexpensive way to provide supplemental insect food for Eastern Bluebirds (Sialia sialis). These brightly colored songbirds are primarily insectivores, meaning their diet consists mainly of invertebrates throughout the year. This DIY approach creates a low-profile platform that bluebirds readily use to access a highly desired food source.
Gathering Materials and Assembly
The construction of this simple feeder requires only a few common items: one clean, empty tuna can, a sturdy nail or screw, and a wooden post or fence rail. Begin by thoroughly cleaning the can to remove any residual oils or fish odors, which could contaminate the food or deter the birds. Before mounting, use a small nail to punch two or three tiny drainage holes into the bottom of the can to prevent water from collecting and spoiling the contents.
Next, select a secure mounting location, such as the top of a wooden fence post or a dedicated wooden pole. Place the can on the post with the open side facing upward, ensuring it sits level to act as a shallow dish. Drive a long nail or wood screw through the center of the can’s base and into the wood below to fasten it firmly. The can must be completely secure and unable to spin or wobble.
The Specific Bait: Mealworms
The success of this feeding station depends entirely on the bait, which must be live or dried mealworms. Bluebirds will not consume typical birdseed mixes, as they are hard-wired to hunt for insects and other small invertebrates. Mealworms are the larval form of the Darkling Beetle (Tenebrio molitor), providing a high-protein and high-fat supplement to their natural diet.
Offer mealworms as a supplement rather than a complete food source, as they are low in calcium relative to other nutrients. Start by offering a small quantity, such as 50 to 100 mealworms, twice a day, especially during the breeding season when parents need extra energy. Offering limited amounts ensures the bluebirds consume the food quickly and prevents other species from monopolizing the feeder.
Optimal Feeder Placement
Proper placement is paramount because bluebirds prefer wide, open habitats where they can spot prey from a low perch. The feeder should be mounted on a post approximately four to six feet above the ground, which is a comfortable foraging height for this species. Avoid placing the tuna can feeder directly next to dense shrubs, thickets, or wooded edges.
Feeder locations should be at least 25 feet away from heavy cover, which can hide ground predators waiting to ambush feeding birds. To increase safety and deter climbing mammals like raccoons or squirrels, mount the post with a stovepipe or cone-shaped baffle installed below the feeder. This combination of open-area placement and predator defense significantly increases the likelihood of bluebird visitation.
Feeder Maintenance and Safety
The tuna can requires daily monitoring to ensure the health and safety of the visiting bluebirds. Uneaten live mealworms can quickly die and mold, so any leftovers must be removed each evening to prevent the spread of bacteria. The small drainage holes allow rainwater to escape, but they must be kept clear of debris.
The metal can is susceptible to rust, which can occur quickly in wet weather and contaminate the food source. Check the interior regularly for signs of corrosion and replace the feeder immediately if rust develops. Consistent maintenance, including offering only a small quantity of food that is quickly consumed, helps minimize the attraction of aggressive birds like House Sparrows.