Start with what sits in the cage every day
The most reliable calcium source for a pet bird is one that is always available for the bird to use as it chooses. A cuttlebone clipped to the cage bars gives a bird calcium it can scrape off with its beak a little at a time, and a mineral block serves a similar purpose for birds that ignore cuttlebone. Fix it near a perch the bird already uses, not in a forgotten corner, and replace it when it becomes soiled, thin, or crumbles away. These cage fixtures are a base layer, not the whole answer, because some birds chew them mostly for beak exercise and take in only modest amounts.
Leafy greens and vegetables that carry calcium
Food is where most of a bird's calcium should come from day to day. Dark leafy greens are the standouts: kale, bok choy, collard greens, dandelion greens from a pesticide-free source, and broccoli, including its leafy stalks, all contribute calcium in a form birds use well alongside the rest of a varied diet. Offer them washed, chopped to a size your bird will handle, and presented in ways that encourage eating rather than throwing, such as clipped to the bars, woven through them, or mixed into chop. A bird that only licks at a whole leaf hung once a month is not getting much, so frequency matters: small amounts several times a week beat a rare large serving that mostly goes to the cage floor.
The staple diet and a note on balance
A quality formulated pellet already contains calcium balanced against phosphorus and vitamin D, which is why birds eating mostly pellets rarely need heavy extra supplementation. Seed-heavy diets are the opposite problem, since seed is low in calcium and high in fat, so a seed-fed bird benefits most from the greens and cuttlebone above and from a gradual move toward a more balanced staple. Calcium does not work alone: your bird also needs safe access to natural light or appropriate full-spectrum lighting indoors and the vitamin D that comes through a balanced diet to actually use the calcium it eats. That is why throwing more and more calcium at a bird on a poor overall diet rarely fixes the underlying gap.
Birds that need more, and signs to watch
Egg-laying hens use far more calcium than other birds, because every shell is drawn from their own reserves, and chronic layers can deplete themselves quickly. For them, keep cuttlebone constantly available, lean harder on the calcium-rich greens, and talk to an avian vet early rather than waiting for trouble. Warning signs that calcium may be low or that laying is straining your bird include soft or thin-shelled eggs, trembling, weakness, loss of coordination, or a hen straining without producing an egg, and that last picture is an emergency that needs a vet the same day. A non-breeding bird that suddenly seems weak or shaky should also be seen promptly rather than simply given extra cuttlebone at home.
What not to do with calcium
More is not automatically better. Sprinkling concentrated supplements over all food every day without veterinary guidance can overshoot, and excess calcium carries its own risks, particularly for the kidneys. Grit is a separate confusion worth clearing up: most parrots, who hull their seed before eating it, do not need insoluble grit, and offering it freely can cause problems, so do not treat a grit pot as a calcium strategy. If your bird refuses cuttlebone entirely, try a mineral block, try a different position in the cage, and use the food route more deliberately before reaching for a supplement product.
Tracking what your bird actually takes in
Because a calcium source only counts if the bird eats it, a simple weekly note of what was offered and what disappeared is genuinely useful, especially for a laying hen or a bird converting from seed. KinsLe Care Teams lets you log the cuttlebone checks and greens offered for your bird as part of the daily care list, so a slow drift away from calcium-rich foods shows up before it becomes a problem.