Hopper feeders: capacity, ledges and the jam nobody diagnoses

The short answer

• A hopper is a covered reservoir that gravity-feeds seed onto a ledge, so it keeps seed dry and reaches more species than a tube: 17 of the 34 species in our dataset use one.
• Ledge width is the setting that decides your species list. Under 1.5 in is small birds only; 2.5 to 3 in lets cardinals feed; 4 in and over admits jays, doves and grackles.
• Capacity works against you. Fill only what the yard clears in five to seven days, even if the hopper holds three times that.
• A hopper that stops emptying while birds still visit is bridged, not empty: the seed has arched over the gap and needs breaking, sieving and a wider outlet.
• An unwashed hopper is the worst feeder in the yard: dark, enclosed, humid, and holding seed at the bottom that never rotates out.

A hopper is a roofed reservoir with a gap at the bottom, sitting over a ledge. Gravity does the work: as birds take seed off the ledge, more slides down to replace it. The roof keeps rain off the reservoir, the clear sides let you see the level, and the ledge gives birds somewhere to sit rather than cling.

That ledge is why hoppers reach further than tubes. Seventeen of the 34 species in our dataset will use a hopper, against twelve for a tube, and the extra names are the ones people actually want: cardinals, grosbeaks, jays.

Top top-tier favorite Yes eats readily Some takes occasionally Rare rarely No not a feeder food

The ledge is the setting#

Everything about who feeds at a hopper comes down to a number most people never measure: the width of the flat surface between the seed outlet and the outer lip.

A Northern Cardinal is a 45 g bird that feeds sitting down and needs its whole body on the surface. A Mourning Dove at 120 g needs more again, which is why doves usually feed on the spilled seed below a hopper instead of on it. If your goal is cardinals and your problem is grackles and blackbirds, the 2.5 to 3 in band is the useful compromise: enough for a cardinal, tight enough that a grackle has to work at it. Pair it with safflower, which cardinals take readily and grackles largely refuse, and you have solved the problem without buying a mechanism. The seed side is worked through in safflower seed.

Capacity is a liability#

A hopper holds around 100 fl oz, which at our working bulk density for black oil sunflower is roughly 2.5 lb. It is sold on that volume: fewer trips outside, fewer refills in January. In practice large capacity is how hopper feeders go wrong.

Work it through. If your yard takes half a pound of seed a day, a full 5 lb hopper is a ten day supply, and the seed at the very bottom has been sitting in a warm, dark, humid box for the whole of that. If your yard takes a quarter of a pound a day, which is normal for a new or quiet station, you are looking at three weeks. Sunflower does not stay good for three weeks in a damp reservoir in July.

The rule we use: fill only to the level the yard clears in five to seven days, four in humid heat. Mark that level on the glass with a strip of tape. A 5 lb hopper filled to 1.5 lb is a perfectly good 1.5 lb feeder, and it is a much safer one.

Roof geometry, and where the rain actually gets in#

The roof stops vertical rain. Nothing about a hopper stops wind-driven rain, and wind-driven rain is what wets the seed.

Rain in a moderate wind arrives at roughly 45 degrees. At 45 degrees, water clears the roof edge and lands on the ledge unless the roof overhangs the ledge by at least as much as the vertical drop from the roof edge down to the ledge surface. So if the eave sits 3 in above the ledge, you need 3 in of overhang past the outer lip to keep the ledge dry in a blow. Most hoppers give you half that.

Three consequences follow, and all three are fixable:

• Wet seed on the ledge wicks up into the outlet. That damp seed swells against the gap and becomes the plug described in the next section. Check the ledge after rain: if it is wet, the outlet is being fed water.
• A shallow roof pitch holds water. Under about 20 degrees, rain pools on the roof, sits in the seam around the lid, and finds its way in. Steeper roofs shed properly.
• Drainage holes in the ledge are not standard, and should be. If the ledge has no holes, drill three or four small ones through the flat surface at the low points. It voids nothing and it is the single most effective modification you can make to a hopper.

Turn the feeder so the open ends face across the prevailing wind rather than into it, and site it where a shrub or fence takes the edge off the weather without giving squirrels a launch point. The trade between shelter and squirrel access is covered in where to put a bird feeder.

Seed bridging: the failure nobody diagnoses#

Here is the classic scene. The hopper looks two thirds full through the glass. Birds arrive, land on the ledge, find nothing, and leave. You conclude the birds have gone off the seed.

They have not. The seed has bridged.

What is happening. Granular material can form a self-supporting arch across an opening. When seed is slightly damp, or when the bag has produced a lot of dust and broken hull fragments, the particles interlock and build an arch over the outlet gap. The arch carries the weight of everything above it, so the column stops descending. From outside, the feeder is full. At the ledge, nothing is coming out.

How to confirm it in ten seconds. Push a stick or a bamboo skewer up through the outlet gap. If the seed above suddenly drops, it was bridged. If nothing moves, you have a solid plug of caked seed, which is the same problem after a few more damp days.

Why it happened. One or more of these:

• The outlet gap is too narrow for the seed. As a working rule the gap wants to be at least about three times the largest dimension of the seed, so roughly 1.25 in for in-shell sunflower. Gaps sized for millet will bridge with sunflower.
• The seed is damp, from wind-driven rain on the ledge or condensation inside the reservoir.
• The bag was full of fines. Dust and hull fragments are the binder that makes an arch hold. Mixes containing cracked corn are the worst offenders in humid weather. See reading a birdseed mix label.

The fix, in order. Empty the hopper completely. Sieve the seed through a colander and discard the dust. Dry the reservoir. Refill with a single clean seed, not a mix. If it bridges again with dry seed, the gap is genuinely too small and the feeder is only usable with a smaller seed.

Mounting a loaded hopper#

A full hopper is a heavy object with a large flat roof, which is a bad combination on a hanging hook. It swings, seed skips off the ledge in the wind, and the roof reads to a squirrel as a landing pad.

Pole-mount it. Most hoppers have a socket or a mounting plate in the base for exactly this. A 1 in smooth pole set in the ground, feeder platform at about 5 ft, a wraparound or torpedo baffle at roughly 4.5 ft, and 7 to 10 ft of clear space in every direction. Get that geometry right and the least squirrel-resistant common feeder becomes squirrel-proof, which is a much better result than any hopper mechanism will give you. See poles, hooks and hangers for hardware that will hold the weight without leaning after a winter, and for the baffle diameters that actually work on a pole this heavy.

If the hopper must hang, hang it from a chain rather than a cord (cord chews through), and accept that you will be managing squirrels rather than preventing them.

Why an unwashed hopper is the worst feeder in the yard#

Every design gets dirty. The hopper gets dirty in a way that is uniquely hard to see and uniquely good for microbes.

• It is enclosed and dark. A tray dries in the sun and gets sterilized by UV. A hopper reservoir never sees direct light and never fully dries.
• It holds humid air. Warm damp air enters through the outlet, cools overnight against the glass, and condenses on the inside of the panels, right onto the seed.
• The bottom corners never rotate. Seed in the corners of the reservoir, below the level of the outlet, may sit there for months while everything above it is replaced.
• Birds stand in the food. The ledge is a perch and a plate at the same time, so droppings land in the seed, and the wet ledge keeps them there.

That combination is why hoppers turn up so often in moldy seed complaints, and why they matter for disease transmission at feeders.

The routine: every two weeks in cool dry weather, weekly in humid heat. The hopper-specific part is the reservoir. Take the roof or a side panel off (if it does not come apart, this is the wrong feeder to own) and get a bottle brush into the corners and the seam above the ledge, because that is where the caked layer forms and where a rinse never reaches. Then run the standard wash, disinfect and dry routine from how to clean a bird feeder. Wet seed goes into a wet hopper and the cycle starts again.

What to fill it with#

The hopper handles a wider range of foods than a tube, because seed sits on a surface rather than squeezing through a port. In practice, four fills are worth using:

• Black oil sunflower. The default, and the seed that best matches the hopper's species list.
• Safflower. The cardinal-friendly, grackle-hostile option. Expect a two to three week adjustment while the regulars work out it is food.
• Striped sunflower. Thicker hull, so small-billed birds struggle and jays and grosbeaks do not. A useful selective fill in a jay yard.
• A sunflower and millet split, only if you have a wide ledge. Millet on a hopper mostly gets swept onto the ground by sorting birds, which is fine if you intend to feed juncos and sparrows below, and a waste if you do not. Millet belongs on a ground tray.

If you are still deciding between designs, the trade-offs are laid out in how to choose a bird feeder, and the direct head to head is in tube versus hopper.

Frequently asked questions#

Will cardinals use a hopper feeder?

Yes, and a hopper is one of the better cardinal feeders, provided the ledge is wide enough to stand on. A Northern Cardinal weighs about 45 g and feeds sitting rather than clinging, so it needs roughly 2.5 to 3 in of flat ledge. Many hoppers ship with a 1 to 1.5 in lip, which small finches use happily and cardinals reject. If cardinals feed on the ground under your hopper but never on it, measure the ledge before you blame the seed.

How much seed should I put in a hopper feeder?

Only what the birds clear in five to seven days, and four in humid heat. A typical hopper holds around 2.5 lb of sunflower, which in a quiet yard is weeks of seed sitting in a dark, warm reservoir. Mark a fill line partway up the glass with tape, fill to that line, and move the line up or down after a fortnight of watching. Underfilling costs nothing. Overfilling produces the clumping, bridging and mold that kill hoppers.

Why has my hopper feeder stopped letting seed out?

It has bridged. Damp seed and seed dust bind into an arch that spans the outlet gap, so the seed above it stops descending and the feeder looks two-thirds full while the ledge stays bare. Tap the sides sharply, push a stick down through the outlet from the top, then empty the hopper completely and sieve out the fines. Long term, avoid mixes with cracked corn and dust in humid weather, and check that the outlet gap is at least about 1.25 in for sunflower.

Where should a hopper feeder be mounted?

On a smooth pole in open ground, not hanging from a branch. A loaded hopper is heavy and swings badly, and its wide roof gives squirrels an easy landing platform. Pole-mount it at about 5 ft, fit a baffle at roughly 4.5 ft, and keep 7 to 10 ft of clear air on all sides. Pole mounting also stabilizes the feeder, which matters because a swinging hopper spills seed off the ledge every time the wind gets up.

Is a hopper or a tube feeder better?

A hopper reaches more species and holds more seed; a tube keeps seed fresher and is easier to wash. If you want cardinals, grosbeaks and jays alongside the small birds, the hopper wins on the ledge alone. If you have a small quiet yard, or you already know you will not wash a feeder often, the tube is the safer choice because there is less dark, enclosed volume for seed to sit in.

Sources and further reading

1. Types of Bird Feeders Cornell Lab of Ornithology, Project FeederWatch Hopper feeder design and the species it serves; Cleaning routine and interval
2. Bird Feeding and Care National Audubon Society Feeder placement and food selection