Feeders

Best Bluebird Feeders: Mealworm Dishes That Keep Starlings Out

By Beak & Branch Editorial · Published August 20, 2026

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Our picks below are research-based — built from manufacturer specs, long-term owner feedback and independent reviews. We buy and field-test top picks on a rolling basis and update each guide as hands-on results come in. How we work.

A bluebird feeder is not a feeder in the sense the rest of the feeders section means it. Bluebirds can’t crack a sunflower shell — they are insect-and-fruit birds — so a hopper of seed will not reliably bring them in. They will occasionally take hulled sunflower or peanut chips, but nothing in a standard seed mix targets them. What a bluebird feeder actually is: a small dish of mealworms wrapped in a structure that starlings, mockingbirds, jays and robins cannot get into. The dish is trivial. The exclusion is the product.

That reframing settles most of the buying decision, because the specification that matters turns out to be a single small number.

The number that defines the category

A round entrance hole of 1 9/16 inches (40 mm) or smaller excludes European Starlings. That figure is the exclusion ceiling, not the point at which starlings start getting in — it entered the literature because Aylesworth and Mackintosh fixed a starling problem by fitting 1 9/16-inch patches over larger holes. Both accepted bluebird entrance sizes, 1½ inches and 1 9/16 inches, sit at or under that ceiling, so both are starling-proof and choosing between them costs you nothing in starling protection. Cornell’s NestWatch is more conservative: it lists 1 9/16 inches as the smallest hole a starling can enter and advises selecting a smaller size, which is one reason 1½ inches remains the default.

Purpose-built bluebird feeders use a 1½-inch entrance because that is the Eastern and Western Bluebird nestbox standard, comfortably over what an Eastern Bluebird needs — not because 1 9/16 is a danger line. Same logic sets the entrance on a proper bluebird house.

Risk begins materially above 1 9/16 inches, and with any hole enlarged or gnawed wider by flickers or squirrels. The bluebird-conservation reference site Sialis records that Art Aylesworth could find no documented case of starlings using a 1 9/16-inch hole unless it had been enlarged that way.

Two honest complications sit on top of that clean number.

Mountain Bluebirds take the bigger of the two safe sizes. NestWatch lists a 1½-inch hole for the Western Bluebird, while North American Bluebird Society guidance recommends 1 9/16 inches for Mountain Bluebirds and anywhere Mountain, Western and Eastern ranges overlap — recommended precisely because that size still keeps starlings out. Either choice is starling-proof; west of the Rockies the larger one simply gives a bigger bird easier access. You will also see 1⅝ inches quoted for Mountain Bluebirds: that was Duncan Mackintosh’s original size, and it is superseded. Starlings were reported using 1⅝-inch boxes in 1984 and the recommendation was changed to 1 9/16 inches as a result. Treat 1⅝ as history, not a current option.

Cage mesh is usually not a true 1½ inches. Sialis notes that the mesh on many cage-style feeders falls short of a genuine 1½-inch opening and can be too tight for larger Mountain and Western Bluebirds. Measure the gap before assuming a “caged bluebird feeder” fits your birds.

Three designs, and who each is wrong for

Open dish or tray. A shallow container with drainage and a few perches. Zero exclusion — starlings empty it, mockingbirds guard it — so it works only as a scheduled feeder you fill while standing there, and as stage one of training. Wrong for anyone who wants to fill a feeder and walk away.

Caged / barrier-guard. A dish inside a wire cage with roughly 1½-inch openings. Best compromise on price and reliability: birds see straight through, so there’s little hesitation, and the guard is passive. Wrong for Mountain or Western Bluebirds where the mesh measures under 1½ inches, and wrong if you need capacity — most hold a token amount.

Enclosed box with entry holes. A roofed box with 1½-inch holes at the ends and clear panels in the sides. Strongest exclusion, best weather protection, and the one design that reliably keeps dried mealworms dry. It is also the design with the most reported failures-to-launch: birds hesitate to enter a cavity to feed, and once inside, some panic at the clear panel instead of finding the hole they came through. Skip the training period below and this feeder just hangs there full.

The Gilbertson variant splits the difference. Designed by Minnesota bluebird conservationist Steve Gilbertson, it is a roofed feeder open on all four sides, with a horizontal rod across each opening that a bluebird slips past and a robin or mockingbird cannot. One rod is removable, so you can open it up during training. The choice for shy birds and for anyone whose first enclosed feeder was ignored — at the cost of less absolute exclusion than a hole, and open sides that let rain and squirrels reach the dish.

Best overall: JCS Wildlife Ultimate Enclosed Bluebird Feeder

The Ultimate is the full expression of the enclosed design: recycled poly lumber with clear acrylic panels, 1½-inch entrance holes, and four half-cup dishes inside holding roughly two cups of dried mealworms. Poly lumber is the right material here — it doesn’t rot, it hoses clean, and mealworm dust plus rain is exactly the mess that destroys cedar feeders over a few seasons. Owner feedback is unusually strong on the central claim, with repeat reports of starlings shut out entirely.

Two caveats. It is expensive for what is structurally a box with cups in it, and JCS runs it in and out of backorder. It is also the design most likely to sit unused for a fortnight — budget for the training routine below. If you want the same idea in wood, Kettle Moraine’s cedar hanging bluebird feeder (11 × 7 × 8 inches, 1½-inch entries at both ends plus holes in the plexiglass windows, hinged roof) is the smaller, cheaper, higher-maintenance alternative.

Best caged feeder: Erva Barrier Guard Bluebird Feeder (BBF1)

Erva’s barrier-guard feeder is 14 inches wide by 8 tall — powder-coated top and bottom with vinyl-coated wire mesh between them at 1½-inch openings, around a glass cup 3¼ inches across and 1 inch deep. The glass is the quietly excellent part: dishwasher safe, so cleaning is not a chore you’ll skip, and mealworm residue in a plastic dish goes rancid faster than people expect.

Wrong for anyone who wants to fill a feeder for the week — that cup holds about two handfuls, a day’s serving and no more. It is also priced like the American metal product it is. Owner accounts consistently report that starlings don’t give up so much as get relegated to picking up worms dropped by birds inside, which is a fair description of what “starling proof” means in practice across this entire category.

Best open-sided design: DutchCrafters Poly Gilbertson Feeder

The large covered poly Gilbertson runs about 11.5 × 11.5 × 3.75 inches: a roof, a central 1-cup stainless steel dish, and four rod-guarded open sides with about 1.25 inches of clearance under each horizontal rod. Buy it if bluebirds in your yard have already refused something enclosed — they never have to commit to entering a cavity, because they can see through and out the far side from every approach. The removable rod turns it into an open tray for the training week and back into an exclusion feeder afterwards.

The trade, plainly: rod spacing discriminates by body size rather than by a hard aperture, so it deters mockingbirds and robins without the near-absolute guarantee of a 1½-inch hole, and the open sides let weather and squirrels reach the dish. Roofed or not, don’t leave dried mealworms in it through rain.

Best for training and small budgets: Songbird Essentials Hanging Mealworm Dish

The SE517 is a 6-inch plastic dish with drainage holes in the corners and four perches around the rim, on a hanging cord. It excludes nothing — and that is the point. This is the dish for week one, out in the open where birds can see the worms moving, and the dish you keep afterwards for supervised morning feeding. Drainage matters more here than anywhere else in the category: a dish without corner holes turns dried mealworms into porridge in one shower.

Wrong for unattended feeding anywhere with starlings or a resident mockingbird, which is most of the eastern United States.

Where to place a bluebird feeder

Open ground, roughly 4 to 6 feet up on a pole — the same mounting height NestWatch gives for bluebird boxes — with a fence line, wire or small tree within a few yards. Bluebirds hunt by perching and dropping onto prey, and they want a lookout before they commit to a feeder.

Distance from the nest box is where advice splits. Sialis recommends siting the feeder about 100 feet from a nest box, reasoning that concentrating food beside the box draws predators and nest competitors to it, and using a close-in feeder only during training. Plenty of retail guidance says the opposite. The conservative reading: keep it inside the pair’s territory and within sight of their perches, but never on the box itself. Our bluebird house placement guide covers the box side of that geometry.

Keep it away from your seed feeders too — a mealworm dish twelve feet from a sunflower tube gets discovered by every bird in the yard, and the seed guide explains why nothing in that tube interests a bluebird anyway.

The training period

Nobody’s bluebird feeder works on day one. The published method is consistent across bluebird-society guidance:

1. Start visible and open. A dozen live mealworms in a shallow dish, in the open, near a perch the birds already use. Live worms move, and movement gets noticed; bright blue flagging or a coloured dish helps.
2. Feed on a schedule. Same place, same time, early morning. Bluebirds learn a routine fast and will be waiting for you within days.
3. Move the dish onto the feeder once they’re taking worms reliably — on top first, then inside.
4. Open the feeder up. Remove a plexiglass panel or a Gilbertson rod for a few days so entry is obvious, then put it back.
5. Walk the feeder to its final spot in short moves over several days.

Skipping straight to step five is the commonest reason a well-chosen feeder gets returned.

Feeding rules that matter more than the feeder

Mealworms are a treat, not a diet. Fawzi Emad, quoted on Sialis, suggests offering about 15 mealworms per bluebird per day, and Sialis itself advises limiting quantities to no more than 15 per bird per day, offering them only as an occasional treat, in bad weather or for a widowed adult; the same page notes birds take roughly 3 to 10 worms per visit. NABS guidance quoted alongside it allows more for a pair actively feeding nestlings: “A hundred or so worms offered morning and evening would be adequate for a pair with a box of nestlings.” Treat the low figure as the everyday default and the high one as a nesting-season exception.

Calcium is the welfare issue. Mealworms are calcium-poor, and nestlings raised on too many can develop metabolic bone disease. Dusting worms with calcium carbonate powder is the standard fix; a wild, varied insect diet is better than either.

Never put mealworms inside a nest box. Nestlings must be fed by their parents, and loose worms just burrow into the nesting material.

Dried or live? Live worms are far more visible, and are what you want for training. Dried are what most feeders are built around afterwards — cheaper, storable, useless once wet. Our mealworms for bluebirds guide covers sourcing and storage.

Frequently asked questions

What size hole does a bluebird feeder need? 1½ inches is the standard, and 1 9/16 inches (40 mm) is equally starling-proof — round holes of 1 9/16 inches or smaller exclude European Starlings, so either size is safe. Enlarging to 1⅝ inches — something some bluebirders do in winter for easier access — does let starlings in, which is why Sialis pairs that winter enlargement with the advice to fit a 1½-inch predator guard block over the holes in summer to reduce them back down.

Do bluebirds eat birdseed? Essentially no — they cannot open shelled seed. They will occasionally take hulled sunflower chips, suet nuggets or fruit, but insects and berries are the real diet, which is why mealworms are the basis of this whole feeder category.

Is a caged bluebird feeder really starling proof? It stops them reaching the dish, which is what matters. It does not make them leave — expect starlings loitering underneath for dropped worms, and a resident mockingbird guarding the feeder from outside regardless of what’s inside it.

Why won’t my bluebirds use the feeder? Almost always because nobody taught them it exists. Open it up, put live worms in a visible dish, feed at the same time each morning, then rebuild the enclosure around them over a week or two.

This guide is compiled from manufacturer and retailer listings and from published guidance from Cornell’s NestWatch, the North American Bluebird Society and the bluebird-conservation reference site Sialis; where those sources disagree, the disagreement is stated rather than resolved. We have not tested these feeders ourselves. We plan to buy top picks for hands-on yard testing, and this guide will be updated, with our own photos, as results come in. See how we test.