Feeding During Nesting Season: What Helps and What Harms

The short answer

• Almost no North American songbird raises chicks on seed. Nestlings are fed insects and other invertebrates for protein and moisture, so a feeder supports the parents, not the brood.
• That is still worth doing: every minute an adult does not spend cracking seed for itself is a minute spent hunting insects for the nest.
• Whole peanuts and large hard chunks are the real hazard, because an adult can carry one to a nest whole. From hatching onwards, offer peanuts chopped or in a mesh feeder that forces small pieces.
• Mealworms are useful and should be capped. They are protein-rich but carry far more phosphorus than calcium, so they belong as a supplement. Our working cap is about 10 to 15 worms per adult bird per day, not a staple.
• Do not open a nest box in the last third of the nestling period. For bluebirds and similar cavity nesters, stop inspections around day 12 to avoid forcing an early fledge.

A house finch pair at your feeder in June is not collecting food for their chicks. They are refuelling themselves between hunting trips. Nearly every North American songbird, including the committed seed-eaters, raises its young on insects and other invertebrates, because a growing chick needs protein and water content that a sunflower kernel cannot supply.

That one fact rearranges everything about summer feeding.

What is actually going into the nest#

Caterpillars, above all. Then spiders, beetles, flies, grasshoppers, moths and whatever else the adults can catch within a few hundred feet of the nest. Chickadees hunt caterpillars in oak foliage. Bluebirds drop onto grasshoppers from a perch. Robins take earthworms. Even goldfinches, one of the very few species that does feed its young largely on seed, deliver it as regurgitated seed pulp rather than as whole kernels.

The consequence is that a yard with insect-supporting vegetation raises more birds than a yard with a bigger feeder. Native trees and shrubs host the caterpillars, the caterpillars feed the chicks, and nothing in a seed bag replaces that chain. See native plants and cover.

So what is the feeder doing in June?#

Buying time. A pair provisioning a nest may make a food delivery every few minutes through the daylight hours for a fortnight or more. Any calories the adults get quickly and reliably for themselves are foraging minutes returned to the brood.

That is a real contribution, and it is also a modest one. Think of your feeder in nesting season as a service station for the parents, not a nursery. It changes what you should expect: fewer birds, shorter visits, adults snatching a seed and leaving rather than sitting at the port.

Then, in a burst around three to five weeks after nesting starts, the fledglings arrive: scruffy, short-tailed, sitting on the perch shrieking while an exhausted parent shells seed and posts it into their open bill. That is the best sign your yard is working.

The choke risk, and the formats that remove it#

This is the one genuine hazard of nesting-season feeding, and it is easy to avoid. Adults do sometimes carry feeder food to a nest. Something large, dry and hard can choke a nestling.

The peanut fix is mechanical. A wire mesh peanut feeder forces birds to chip pieces off rather than take a nut whole, which solves the problem without giving up peanuts for three months. If you offer loose peanuts on a tray, chop them. Details on grades and formats are on peanuts for birds, and the list of things that should never be out at all is on what not to feed birds.

Mealworms: genuinely useful, and easy to overdo#

Mealworms are the one feeder food that plugs directly into the insect diet, which is why they work so well for bluebirds, wrens and robins in nesting season.

Skip for this species: Striped, Safflower, Nyjer, Millet, Cracked corn, Peanuts (in shell), Nectar.

The catch is mineral balance. Mealworms are rich in protein and fat but carry far more phosphorus than calcium, and calcium is exactly what a growing chick and a laying female need most. A brood fed largely on mealworms can develop bone problems. Wild parents are collecting a varied insect diet, so the fix is not to stop offering them, it is to keep the offering small enough that it stays a supplement.

Our working rule:

• Cap it at roughly 10 to 15 worms per adult bird per day, offered in a dish.
• Offer at fixed times, morning and late afternoon, so the dish empties within the hour rather than sitting out all day.
• Never run an all-day supply. A dish topped up continuously is how a pair ends up provisioning a nest mostly from your dish.
• Pair it with calcium. A separate dish of prepared eggshell or crushed oyster shell covers the mineral side. Preparation method is on the spring feeding page.

Portion control, live versus dried, and dish designs are covered on mealworms and mealworm feeders. If your target is bluebirds, the timing matters as much as the amount: a dish started in early spring, before nesting, trains the pair to a location they will use through the season.

Nest box hygiene#

A box is a shared, reused cavity, which makes it both valuable and a parasite reservoir.

Between broods. Once young have fledged and the adults have stopped visiting, remove the old nest material and brush the box out. Old nests hold blowfly larvae, mites and fleas, and a second nest built on top of the first raises the next brood closer to the entrance hole, within reach of predators.

Cleaning method. Scrape out the debris, brush the interior, and wash with water or a weak bleach solution (one part household bleach to nine parts water) if the box has held a failed nest or looks fouled. Rinse, then leave the box open in the sun until it is bone dry. Never use insecticide or any residual chemical inside a box.

End of season. Clean out in autumn rather than spring, which leaves the box available as a winter roost. The roost box conversion is covered on winter bird feeding.

Feeders near boxes. Keep the seed feeder some distance from a nest box. A busy feeder next to a box concentrates traffic, droppings and attention right where you want a nest to be inconspicuous.

Not disturbing the nest#

Three rules cover it.

1. Stop checking in the last third of the nestling period. For bluebirds and similar cavity nesters, that means no box openings from about day 12. Opening a box near fledging can push chicks out early, before they can fly properly. Established nest-monitoring programs all set a cut-off of this kind, and it is the rule most worth keeping.
2. Check briefly, in good conditions. If you monitor, do it once a week at most, in mild dry weather in the middle of the day, for under a minute. Not at dawn, not at dusk, not in rain or cold, and never linger, since a predator can follow your route.
3. Leave open-cup nests alone entirely. Do not prune the shrub, do not move the hanging basket, do not part the branches to show someone. Active nests, eggs and young of native species are legally protected in the United States and Canada, and disturbance is also just the fastest way to cause abandonment.

Fledglings on the ground are normal. Most songbirds leave the nest before they can fly well and spend a few days hopping about being fed by parents who are usually nearby and watching you. Unless a bird is obviously injured or in immediate danger, leave it. The single most useful thing you can do for it is keep cats indoors for that fortnight: see cats and feeders.

The nesting season checklist#

• Peanuts chopped or in mesh, from hatching until the last brood fledges.
• Suet in small nuggets or no-melt dough, never large hard chunks.
• Mealworms capped and timed, with calcium offered separately.
• Feeders cleaned weekly, because warm weather and concentrated adults are the risk combination.
• Nest boxes cleaned between broods, never opened after about day 12.
• Cats in, especially in the fledging weeks.

Everything else about running feeders through the warm months, including spoilage rates and the water that matters more than seed, is on summer bird feeding.

Frequently asked questions#

Do baby birds eat birdseed?

Essentially no. Nestlings of nearly every North American songbird, including cardinals, chickadees, finches and sparrows whose adults live on seed, are fed insects, spiders, caterpillars and other invertebrates. Chicks need the protein for growth and the moisture content, and seed provides neither well. Adults do bring the occasional soft item to a nest, but the diet that builds a chick is animal protein. That is why insect-rich native plants do more for nesting success in a yard than any feeder.

Should I stop feeding birds when they are nesting?

No. Feeding adults during nesting is a support, not an interference: every foraging trip an adult does not have to make for itself is time spent hunting insects for the brood, and time is the scarce resource when a pair is provisioning a nest every few minutes for two weeks. What must change is the format of the food. Anything large, hard and swallowable whole should be removed or broken up while chicks are in nests.

Are whole peanuts dangerous for baby birds?

They can be. A whole peanut kernel is large enough to choke a nestling, and adults will carry food they find at a feeder straight to the nest. From the point chicks hatch through to fledging, offer peanuts chopped into small pieces or in a wire mesh feeder that forces birds to take fragments rather than whole nuts. The same reasoning applies to large hard chunks in suet cakes and to whole in-shell nuts.

Are mealworms bad for birds?

They are useful in moderation and poor as a staple. Mealworms are high in protein and fat but carry far more phosphorus than calcium, and a chick raised largely on them can develop bone problems. Wild parents feeding a varied insect diet are not at risk from a handful of mealworms, so the rule is simply a cap: offer roughly 10 to 15 worms per adult bird per day in a dish, let them be taken within the hour, and stop. Never let a dish become an all-day, all-you-can-take supply.

When should I clean out a nest box?

Between broods and again at the end of the season. Once a brood has fledged and the adults are no longer visiting, remove the old nest material, brush the box out, and clean it with water or a weak bleach solution, then let it dry completely with the lid open. Old nests hold parasites and can encourage a second brood to be built on top, raising chicks closer to the entrance where predators can reach them. Do not use insecticides inside a box.

Is it illegal to disturb a bird nest?

In the United States, active nests, eggs and young of native migratory birds are protected under federal law, and similar protections apply in Canada. Non-native house sparrows and European starlings are not covered. In practice that means you do not move, remove or destroy an active nest of a native species, even one built somewhere inconvenient. Wait until the young have fledged and the nest is genuinely inactive, and check your state or provincial rules if you are unsure.

Sources and further reading

1. All About Birds species guide Cornell Lab of Ornithology Nestling diet and breeding biology by species
2. NestWatch Cornell Lab of Ornithology Nest monitoring protocol, box maintenance and when to stop checking
3. Migratory Bird Treaty Act U.S. Fish and Wildlife Service Legal protection of native birds, nests and young
4. Feeding Birds Cornell Lab of Ornithology, Project FeederWatch Food formats and year-round feeding practice