Feeder Types

Feeder Size and Capacity

The right feeder capacity is whatever your birds finish in about a week. Buy bigger than that and you are not saving effort, you are storing seed outdoors in the weather.

Seed should be eaten within about a week. That single rule decides feeder capacity, and it points the opposite way from the instinct most people buy on, which is to get the biggest hopper available so refilling is rare.

A feeder is not a storage container. It is an open dish in the weather, where humidity, sun and bird droppings all work on the seed. Seed that sits for a month in a large hopper goes rancid, cakes at the bottom, and eventually stops attracting anything, which is one of the more common answers to why no birds are coming to your feeder.

This page gives capacity figures by yard traffic, a method for measuring your own, and the seasonal and food-specific exceptions to the week rule.

Why a week#

Three clocks run at once on seed in a feeder.

The oil clock: sunflower and other oil-rich seeds turn rancid on exposure to air, warmth and light. Rancidity is not dangerous in the way mold is, but birds avoid it.

The moisture clock: every rainfall and every humid night adds water at the top and the bottom of the seed column, and unlike the middle, those layers never really dry. This is the start of the sequence described in moldy, clumped or wet seed.

The contamination clock: droppings, saliva at the ports and hulls accumulate steadily. Longer between empties means longer between real cleanings, and disease risk climbs with both.

A week keeps all three within bounds in most conditions. In summer heat or a wet stretch, shorten it to a few days.

Yard traffic and sensible capacity#

These bands are approximations, offered as a starting point rather than a specification. Regional differences are large, and a yard's traffic changes as birds discover it.

For reference, a quart (about 1 liter) of black oil sunflower weighs roughly three-quarters of a pound (0.35 kg), so a feeder described as holding 3 quarts is holding a little over 2 pounds (0.9 kg).

Measuring your own yard#

Guessing is unnecessary. This takes one week.

1. Fill the feeder and mark the level with a strip of tape on the outside.
2. Note the date.
3. Seven days later, look at where the seed sits.
4. If it is empty before day seven, your capacity is too small or your traffic is higher than you thought. If it is more than a third full, fill less next time.

Repeat in January and again in July, because those two numbers are often very different. Traffic also climbs for the first month or two after a feeder goes up, so do not size anything permanently based on week one. That ramp is normal, and its timeline is covered in how long until birds find a new feeder.

Two small feeders instead of one large#

At the same total capacity, splitting is almost always better.

• Less aggression. A single feeder is a defensible resource, and dominant birds monopolize it. Two feeders several yards apart let subordinate birds eat.
• Less disease. Crowding at a shared surface is a transmission route, which is why spacing is recommended in how many feeders and how far apart.
• Fresher seed. Each feeder turns over faster, and you can run different foods.
• Cheaper mistakes. If one feeder gets rained into or contaminated, you lose half as much seed and half your traffic keeps eating.

The one real argument for a large feeder is deep winter, when daily refilling in snow and dark stops being appealing. Even then, the better answer is often a large-capacity hopper feeder with good weather sealing rather than an oversized tube.

Capacity by feeder type#

Different designs behave differently at the same nominal capacity.

Tubes show you the level, which makes the week test easy. Their weakness is the dead zone below the lowest port, where seed nobody can reach absorbs moisture. Details in tube feeders.

Hoppers hold the most and hide the most. A large hopper can conceal a caked layer for months, so size these conservatively and empty them fully at each clean.

Platforms hold little and should hold less. Put out what will be eaten in a day, because an open tray has no weather protection at all. See platform and tray feeders.

Nyjer feeders deserve the strictest limit. Nyjer dries out and loses its appeal quickly, and finches abandon stale seed abruptly, so fill small and often.

Suet cages hold one cake by design, which is usually right. A cake that lasts more than a week or two in warm weather is a cake going soft and rancid, and in summer that is a reason to switch to a no-melt formulation rather than to buy a larger cage.

The capacity mistakes people actually make#

Four patterns account for most of the wasted seed in American backyards.

Buying for the yard you want. A feeder sized for the flock you hope to attract sits mostly full for a year while the seed in it ages. Start small and scale up once traffic justifies it.

Topping up forever. Pouring fresh seed onto old seed keeps a layer at the bottom that never leaves. That layer is where the caking and the mold begin, and no amount of fresh seed on top fixes it.

Sizing once. A capacity that was right in November is wrong in June. Two measurements a year is enough.

Confusing volume with weight. Feeders are advertised in quarts, liters, pounds and vague words like large. Convert everything to pounds or kilograms before comparing, or you will end up with something twice the size you intended.

Seasons change the answer#

Consumption in a northern yard in January can be several times its July figure. Cold nights, short foraging days and no insects all push birds to feeders, and the effect is discussed in winter bird feeding.

Summer runs the other way. Natural food is abundant, many adults are feeding insects to young, and heat spoils seed faster. Reduce capacity in summer rather than watching seed sit, and keep the same week rule in mind during nesting season.

Nectar is a separate clock entirely. Sugar water spoils in one to two days in hot weather regardless of how full the feeder is, so buy the smallest hummingbird feeder that your visitors empty, and follow the changing schedule in the hummingbird nectar recipe.

Sizing checklist#

• Run the tape-mark test for one week in the current season.
• Choose a capacity that empties in five to seven days, not ten.
• Split the total across two or more feeders wherever the yard allows.
• Underfill in summer, fill fully in a cold snap.
• Empty and clean at each refill rather than topping up, on the schedule in how often to clean bird feeders.
• Re-measure in midwinter and mid-summer, then leave it alone.

A feeder sized this way costs slightly more attention and noticeably less seed, and the birds get food that still smells like food.