Both a moulting hen and a hen losing feathers for another reason can look scruffy, so appearance alone misleads. The reliable separators are pattern, pace, skin condition and how the hen herself behaves. A normal moult follows a recognisable course over weeks and the bird remains well throughout; loss that deserves investigation breaks that pattern in at least one of those four ways.
The shape of a normal moult
A moult typically begins around the head and neck and progresses across the body and wings over a period of weeks, in a broadly even pattern rather than in random bare islands. As old feathers drop, new pin feathers push through: short, waxy spikes that unfurl into fresh plumage, and their presence in a bare patch is reassuring evidence that replacement is underway. Laying usually pauses or stops during a moult because the hen redirects protein into feather growth, and she may eat heartily while looking temporarily threadbare. She stays bright-eyed, active, interested in food and flock life, perhaps a little more retiring because growing pin feathers are tender and handling can hurt; reduce picking her up during this stage.
Loss that breaks the pattern
Investigate when loss is sudden, arriving over days rather than weeks, or sharply patchy, with one area stripped while the rest of the plumage stays complete. Loss concentrated around the vent, or feathers broken off short rather than shed whole, points toward pecking by flock mates or irritation rather than moulting. Bare skin that is red, scabbed, flaky or wounded is never part of a healthy moult. So is any accompanying decline: weight loss you can feel at the breastbone, dullness, reduced eating, droppings changes, or laying that stops outside the usual moult season without pin feathers appearing. A hen who hides, is driven from feeders, or shows wounds on the back of the neck needs flock behaviour examined as carefully as her skin.
Check skin and feather bases in good light
Part the feathers at several sites, including around the vent, under the wings and at the base of the tail, and look at the skin and the feather shafts close to it. Search for moving specks, clusters of eggs cemented at shaft bases, scaly crusts or redness, which suggest external parasites needing flock-level advice from a vet. Work through the whole flock rather than one bird, because pecking and parasites are group problems wearing an individual disguise. Note who pecks whom if you can watch quietly for a while: a single hen losing neck and back feathers while flock mates stay fully feathered is often the target of others, and separating the pattern from a moult is the first step toward solving it.
Record the pattern weekly
Photograph each affected hen from the same angle, in similar light, once a week, and note laying, appetite and any skin findings beside the date. A moult declares itself across three or four of these photographs: loss advances in an orderly direction and pin feathers visibly lengthen. Loss that spreads randomly, deepens in one patch or arrives with sores moves the other way. These dated images give a vet far more to work with than a description of a hen who 'looks bald', and they protect you from relying on memory across a slow-changing flock.
When to involve the vet
Contact a vet for advice when you find parasites, sores, bleeding or broken skin, when a hen loses weight or stops eating, when several hens lose feathers at once outside moult season, or when weekly photographs show loss progressing without pin feather regrowth. Bring the photographs, a note of what the flock eats, and details of recent changes such as new birds, housing moves or feed changes. Moulting hens benefit from steady nutrition and minimal stress while feathers regrow; beyond that general support, treatment for any other cause of feather loss belongs to the vet who has examined the flock picture. Next autumn, compare the new moult against last year's photographs filed under KinsLe's Pet Passport before worrying or relaxing.