How many hummingbirds are really visiting my feeder?

The short answer

• Each fluid ounce of 4:1 nectar actually drunk in a day stands for about 4 to 8 hummingbirds, with 6 as the working figure. A gallon a day is roughly 550 to 1,000 birds.
• The 750 per gallon figure is Stephen Russell's, built on Calder's Black-chinned Hummingbird energetics and an assumption that feeders supply 70% of each bird's energy. Brent Ortego's banding study in central Texas measured about 1,000 per gallon.
• The 60 per gallon figure comes from a magazine answer that a Ruby-throat probably will not drink more than about 2 fl oz a day. That is a ceiling per bird, so it gives the fewest birds possible, not an estimate.
• Subtract evaporation, drips and insects before you convert. A dripping inverted bottle can add one phantom bird a day on its own.
• Nectar counts bird-days of food, not individuals. The peak count times six counts individuals, and in migration even that undercounts.

Every fluid ounce of 4:1 nectar your hummingbirds actually drink in a day stands for about six birds, and the honest range is 4 to 8. If your birds drink 16 fl oz between one dawn and the next, that is 69 to 125 birds' worth of energy, not the 8 or so that the "60 per gallon" rule would give you. The published figures run from 60 to 1,000 birds per gallon, and the lowest is a ceiling repeated as an estimate.

The per-ounce and per-gallon columns are our arithmetic on their figures, at 128 fl oz to the gallon. Patton's grams are converted at the weight Russell used, 144 oz for a gallon of 4:1 nectar, which is about 32 g per fluid ounce.

The conversion, worked#

Measure what disappeared over one full day, subtract what the birds did not drink, then multiply.

A kitchen scale beats the marks on a bottle. Weigh the feeder at dawn and the next dawn: every 4 to 7.5 g gone is one bird-day (Ortego's figure and Russell's feeders-only case).

Worked: a 16 fl oz saucer filled at 6am has lost 11 fl oz by the next 6am, and a covered control jar beside it lost 0.5 fl oz. That leaves 10.5 fl oz drunk: 45 birds low, 62 working, 82 high. "About 60 birds' worth" is as precise as the evidence allows.

Where "60 per gallon" comes from#

It traces to Kenn and Kimberly Kaufman, answering a Birds & Blooms reader who used about a gallon a day: at 4:1, "a ruby-throat probably won't drink more than about 2 fluid ounces per day. A gallon of sugar water could feed about 60 hummingbirds in a day."

"Won't drink more than" is an upper bound on one bird, and dividing a gallon by the most a bird could drink gives the fewest birds that could have drunk it. Two fluid ounces is about 64 g. Dave Patton's heaviest day for a Rufous Hummingbird feeding all day at his feeder in a Louisiana winter was 11.6 g, and Ortego's figure is about 4 g. The ceiling is five to sixteen times anything measured, so 60 is a floor, and a low one. The Kaufmans themselves added that the real number "could be even higher if some are just stopping briefly".

The 0.46 oz in Bird Watcher's Digest is half a gallon divided by 139 birds counted with the times-six rule: one rule of thumb run backwards through another. Like several feeding myths, it survives because arithmetic looks like evidence.

What the two field figures assume#

Stephen Russell, an Arizona hummingbird enthusiast, built the 750 figure from Bill Calder's energetics work on Black-chinned Hummingbirds. The Georgia DNR account says he weighed a gallon of 4:1 nectar at 144 oz, estimated his birds' weight, took feeders to supply 70% of their energy, and calculated that 14% of his nectar was lost to evaporation, wind, ants, bees and yellow jackets.

If your birds have little else to eat, use the 549 column. If your losses exceed his 14%, subtract them, or they become birds that do not exist.

Brent Ortego's is the only per-gallon figure that counted marked birds. With Ross Dawkins at a ranch near San Angelo running some two dozen gallon feeders, he caught at least 100 birds on each of three banding visits two weeks apart. The population estimates were 3,000 and 3,100, with confidence limits he called "pretty large", in a breeding population with few migrants passing.

Subtract what the birds did not drink#

Lanny Chambers' objection on the archive stands: you cannot know what else the birds are eating. You can measure what they did not drink.

• Evaporation. Hang a small jar of the same nectar beside the feeder, covered with fine mesh so nothing can drink. Whatever it loses, the feeder lost too.
• Drips. An inverted bottle in afternoon sun pushes nectar out as its trapped air warms. Our hummingbird feeders page works that out at about 0.2 fl oz a day for 3 fl oz of air space: a phantom bird every day. A saucer feeder does not drip.
• Bees, wasps and ants. Insects on the ports inflate the count by an amount you cannot measure. Clear them first with bees and wasps and ants on hummingbird feeders, then count.
• Other drinkers. Bob Sargent reported at least 13 fledgling Downy Woodpeckers competing with Ruby-throats at his feeders, and orioles take nectar readily. All of it gets counted as hummingbirds.

• Top-tier favorite for: Ruby-throated Hummingbird, Anna's Hummingbird, Baltimore Oriole
• Taken occasionally by: Red-bellied Woodpecker

The feeder must also not run dry. If it is empty before dusk, you measured the feeder, not the demand, and the count is a floor.

Species, weather and strength#

Russell's and Ortego's figures are Black-chinned Hummingbirds on 4:1 nectar. Sheri Williamson's rule on the same archive, about one and a half times body weight in nectar a day, means intake scales with the bird. Our dataset carries Anna's Hummingbird at 4 g and the Ruby-throated Hummingbird at 3 g, so an ounce of nectar in an Anna's yard feeds about a quarter fewer birds.

The archive's quoted qualifications add temperature, day length and migration, which matters for Anna's through the freezing nights of a Pacific winter. Convert only 4:1 nectar, the recipe every figure here assumes: the Kaufmans note that intake varies with sugar concentration.

The count-and-multiply check#

Wait for the moment you see the most hummingbirds at once, count them, and multiply by six. Terry Johnson's Georgia DNR column credits the rule to Nancy Newfield and to banding at feeders, where far more birds are caught than are ever seen together. Count 30, and about 180 different birds fed that day.

The multiplier is less fixed than "six" suggests:

Run both methods on the same day. When the nectar number is well above the times-six count, go back to the subtraction list. When the count is well above the nectar number, you are watching turnover, which is what fall migration looks like at a feeder.

What the number is good for#

Ortego's advice: pick a method you can repeat exactly and read it as a trend for your own yard. Weekly weighings show when your birds arrive and leave, which is what hummingbird feeder timing turns on.

It also settles two decisions. A feeder that drains by midafternoon needs more feeders out of sight of each other, not a bigger one. And with your daily fluid ounces in hand, the nectar calculator sizes the batch so you fill only what gets drunk before it needs cleaning and changing. How our other figures are built is on the methodology page.

Frequently asked questions#

How many hummingbirds does a gallon of nectar feed in a day?

Between about 550 and 1,000, with 750 the usual working figure. Stephen Russell's calculation, based on Black-chinned Hummingbird energetics, gives 750 per gallon of 4:1 nectar when feeders supply 70% of each bird's energy and 549 when they supply all of it. Brent Ortego's mark-recapture work on a breeding population in central Texas found roughly 3,000 birds on 3 gallons a day, or about 1,000 per gallon. The often-repeated 60 per gallon is a floor built from a generous per-bird ceiling.

Does the multiply-by-six rule work?

In late summer, as a rough count of individuals. Wait for the moment the most hummingbirds are at your feeders at once, count them, and multiply by six. The rule comes from banding at feeders, where many more birds are caught than are ever seen together. The banders' own ratios vary: about 4 to 6 in late summer, 3 to 4 in the nesting season, and about 10 on the Texas coast in migration, when the birds present can turn over completely within one to three days.

How much nectar does one hummingbird drink a day?

Roughly 4 to 12 grams of 4:1 nectar, which is about an eighth to a third of a fluid ounce. Ortego's banding estimate works out to about 4 g per breeding Black-chinned Hummingbird. One observer weighed three Rufous Hummingbirds feeding all day at one feeder in a Louisiana winter and recorded 9.4 g a day on average, ranging from 8.2 to 11.6 g. Nothing measured comes close to 2 fl oz, which would be about 64 g.

Why does my nectar count disagree with what I see?

Because the two methods count different things. Nectar used measures bird-days of food: the energy of so many full-time feeder birds. Watching counts individuals, and many individuals take a few sips and move on. If the nectar number is far above your times-six count, suspect leaks, bees, evaporation or other drinkers. If the times-six count is far above the nectar number, suspect turnover in migration or birds feeding heavily on flowers.

Sources and further reading

1. Counting hummingbirds (HUMNET-L list archive) Louisiana State University Museum of Natural Science Russell after Calder, 750 Black-chinned-sized birds per gallon and nearly 6 per ounce; Ortego's mark-recapture estimate of about 3,000 birds on 3 gallons a day; Patton's weighed Rufous intake; banders' seen-to-caught ratios; Chambers' and Newfield's caveats
2. Out My Backdoor: Counting Hummingbirds Is No Easy Task Georgia Department of Natural Resources, Wildlife Resources Division Russell's assumptions (144 oz per gallon, 70% of energy from feeders, 14% lost), 549 per gallon on feeders alone; Newfield's peak count times six
3. What (and How Often) Do Hummingbirds Eat? Birds & Blooms Kenn and Kimberly Kaufman's answer: a Ruby-throat probably won't drink more than about 2 fl oz a day, so a gallon could feed about 60; the origin of the 60 per gallon figure
4. Frequently Asked Questions about Hummingbirds Bird Watcher's Digest The 0.46 oz per bird figure, derived by applying the times-six rule to a half-gallon a day