Red-breasted Nuthatch: the irruption bird that shows up in August

The short answer

• Red-breasted Nuthatch numbers south of the boreal forest swing with the northern conifer seed crop: a failed spruce and fir cone year pushes birds south, a heavy crop keeps them home.
• They move earlier than any other irruptive species, often arriving in late July or August, which makes them the first warning that an irruption winter is coming.
• Black oil sunflower, sunflower hearts, shelled peanuts and suet are all top-tier foods. Corn, millet and fruit are not eaten at all.
• At about 10 g they are half the weight of a White-breasted Nuthatch, with a black eye line, a white eyebrow and rusty underparts.
• They are small enough to work inside a caged feeder, which is the practical way to keep the seed away from squirrels and starlings without losing the nuthatch.

A bird that works your peanut feeder every hour of daylight one winter can be absent for the whole of the next, in the same yard, with the same food out. Nothing you did caused either outcome. The decision was taken by spruce trees a thousand miles north of you, a year earlier.

Why some winters have them and some do not#

Red-breasted Nuthatches are conifer specialists. In winter their natural food is seed extracted from spruce, fir, pine and hemlock cones. Conifers do not produce evenly year to year: they mast, putting out enormous crops in some years and nearly nothing in others, and neighboring stands tend to do the same thing at the same time across whole regions of the boreal forest.

That produces a two-step cycle:

1. A heavy cone year feeds a large winter population and a strong breeding season. Numbers go up.
2. A failed cone year leaves that enlarged population with nothing to strip. The birds move south, sometimes a long way south, in what birders call an irruption.

So an irruption is not caused by cold weather and it is not a sign of a hard winter coming. It is a food failure at the source, one year after a food surplus.

Red-breasted Nuthatches respond to it before anything else does. They are the earliest of the irruptive northern species to move, with birds turning up well south of the breeding range from late July onward, weeks before siskins or crossbills shift.

In the West the same logic applies with different trees, driven by pine and Douglas-fir crops, and irruptions there often show up as an elevational move: birds drop out of the mountains into valley towns rather than traveling far south.

Identification: small, rusty, loud#

The bird is 4.5 in long and weighs about 10 g, which puts it in chickadee territory rather than nuthatch territory as most people picture it.

• Face. A bold black line straight through the eye with a clean white eyebrow above it. The White-breasted Nuthatch has a plain white face with no eye line at all.
• Underparts. Warm rust to orange, strongest on males. Females and young birds are paler and buffier, and in poor light can look almost white, so check the face first.
• Voice. A nasal, repeated, tinny note like a small toy horn, higher and quicker than the White-breasted's slower drawl. In an irruption year you will hear them long before you find them.
• Posture. Head down on the trunk, the same as its larger relative, with no tail prop.

A Black-capped Chickadee is the other common confusion at size, but a chickadee has a black bib, a flat crown, no eye line and no rust below, and it sits upright on a perch instead of hanging off bark.

At the feeder: fast, fearless, always leaving#

Red-breasted Nuthatches are the tamest bird in most yards. They will feed within a few feet of a person standing still, and they are the species most likely to land on a feeder you are holding.

The visit itself is over quickly. The bird arrives, grabs one item, and is gone in two to four seconds. It does not fight for position because it does not need to: at 10 g it slots into gaps between chickadee waves and simply takes what it wants while larger birds are elsewhere. Against a White-breasted Nuthatch it usually loses the argument and goes around.

Caching is constant. Seeds and peanut fragments are wedged into bark, under shingles and in fence rails, and are often covered with a bark chip. In an irruption year an autumn feeder can run down at a rate that makes no sense given how few birds you can see at once, because most of the traffic is storage, not consumption.

Activity spreads across the whole day, with less of the sharp dawn and dusk peak you get from titmice. In cold weather they feed later into the afternoon than most species.

What holds them, and where to put it#

1. Black oil Top
2. Hearts Top
3. Peanuts (shelled) Top
4. Suet Top

Four foods share the top tier. The two that do the most work in practice:

• Shelled peanuts. The highest-value parcel a small bird can carry in one trip, and the fastest way to get a newly arrived nuthatch to commit to your yard. Use a wire mesh peanut feeder or a caged feeder, and keep the volume small, because shelled peanuts absorb damp quickly and spoil.
• Suet. Take-anywhere fat, and the single item most likely to be visited in the first hour after a bird finds your yard. A standard suet cage is fine, and an upside-down cage works just as well because inverted feeding is native to the species.

Black oil sunflower in a tube feeder rounds it out. Cracked corn, millet and fruit are rated zero for this species, so a general seed mix is largely wasted on them.

Two placement points specific to this bird. First, they orient to conifers: a feeder within sight of spruce, pine or hemlock, even a single ornamental, is found faster than one in an open deciduous yard. Second, being 10 g, they pass easily through the mesh of a caged feeder, so you can protect the seed from squirrels and starlings without excluding the nuthatch.

Why one is not coming#

• It is simply not an irruption year. The most common answer south of the breeding range, and there is no fix.
• No conifers anywhere nearby. Wintering birds settle where there is at least some evergreen cover. Adding a spruce or a group of pines is a slow fix that works. See native plants and cover.
• Only seed on offer. A yard with no fat has a much lower chance of holding an arriving bird through the winter. Put up suet in September, not December.
• Everything at your station is large-bird scale. In-shell peanuts, striped sunflower and cracked corn all rate low here. Offer something a 10 g bill can handle.
• The whole yard has gone quiet. That is a different problem, worked through in no birds at my feeder.

An irruption winter, month by month#

July to September. First arrivals, often at suet within a day of appearing. This is when a big year announces itself.

October to November. Numbers settle. Birds that stay are now working a fixed circuit that includes your feeders, and autumn caching is at its peak. Stock accordingly, as set out in fall bird feeding.

December to February. Steady daily visits. Cold pushes them harder onto fat than onto seed.

March to April. Most head back north, usually earlier than the finches do. Keep suet up through April.

May onward. A few stay and nest in southern conifer stands after strong irruptions. If one is still calling in your spruce in May, look for a small excavated hole with a sticky ring of resin around the rim.

Frequently asked questions#

What causes a Red-breasted Nuthatch irruption?

Food supply in the north. These birds live on conifer seed in winter, and spruce, fir and pine crops fail and boom over huge regions at once rather than tree by tree. A good cone year feeds a large, successful breeding season. If the following year's crop fails across the boreal forest, the resulting population has nothing to eat and moves south. That is why irruptions arrive in waves rather than as a steady southward creep, and why two consecutive winters can look completely different in the same yard.

When do Red-breasted Nuthatches arrive in an irruption year?

Earlier than you expect. They are typically the first irruptive species to move, with birds appearing south of the breeding range from late July onward and building through August and September, well before siskins or crossbills. Our working rule: if you see one south of its breeding range before the first of October, stock up, because you are probably in for a winter of them. If none have appeared by early November, that winter is likely to be a quiet one.

What do Red-breasted Nuthatches eat at feeders?

Black oil sunflower, sunflower hearts, shelled peanuts and suet all rate top tier in our dataset. They will also take nyjer, striped sunflower, safflower and mealworms occasionally. Cracked corn, millet and fruit are not on the list at all. In practice a suet cage and a sunflower tube hold them, and shelled peanuts pull them in from farther away than anything else because a peanut is a large parcel of fat that a 10 g bird can carry off in one trip.

How is it different from a White-breasted Nuthatch?

Size and face pattern. A Red-breasted weighs about 10 g against 21 g, so it is chickadee-sized rather than sparrow-sized. It has a black line straight through the eye with a clean white stripe above it, and orange-rust underparts instead of white. The voice is the giveaway at distance: a nasal, tinny, repeated note that sounds like a toy horn, higher and faster than the White-breasted's drawn-out call.

Do Red-breasted Nuthatches stay to breed after an irruption?

Sometimes. After a strong southward movement, a few birds remain through spring and nest well south of the usual breeding range, particularly where there are mature conifers such as planted spruce, hemlock or pine. They excavate their own cavity in soft dead wood and smear sticky conifer resin around the entrance hole, which is thought to deter insects and competitors. If you have conifers and an irruption winter, keep the suet up into May and watch for it.

Sources and further reading

1. Red-breasted Nuthatch Cornell Lab of Ornithology, All About Birds Identification, voice, range and irruptive movement
2. Project FeederWatch Cornell Lab of Ornithology Feeder foods taken by nuthatches and winter finches
3. Guide to North American Birds National Audubon Society Breeding and winter range