Barring helps, but only the close details finish the job
A lost Plymouth Rock stands out from solid-coloured hens at a glance, because her black-and-white barred plumage reads like stripes from across a yard. That first advantage fades quickly, though, since barred Rocks are one of the most common backyard breeds in the country and a neighbourhood may hold several. The difference between "a barred hen" and your barred hen lives in the fine structure of the pattern: how wide the dark bars run, whether they stay crisp or blur into smoky cuckoo shading, and where the barring breaks around the neck and tail. A finder can only use those distinctions if you described and photographed them while she was still scratching in your run.
Reading your hen's particular stripes, comb and legs
Study your Plymouth Rock's barring in good light and put what you see into words a stranger can check. Note whether the bars are narrow and sharply edged or broad and soft, whether the neck hackles look lighter than the body, and whether any patch of feathers grows in solid or off-pattern after a moult. Add her single comb: count its points if they are distinct, and record any bend, nick or pale tip. Her legs should be clean and yellow, so log any scale damage, a missing toenail or an old bumblefoot scar on the foot pad, because a finder can check feet quickly on a caught bird. Together, pattern, comb and feet give three separate confirmations instead of one hopeful guess.
Photographs that make barring comparable
Photograph your Plymouth Rock against a plain background in open daylight, because barring photographed in a dim coop turns to grey mush and cannot be compared with a found bird. Take full views of both sides, a rear view showing tail barring, a close head shot for the comb, and one frame close enough that individual bar width is visible on the breast. Repeat the side views after her annual moult, since regrown feathers can shift how regular the striping looks. Fit a numbered leg band and record the number with the photographs, checking the fit whenever you handle her, because a band buried under dense thigh feathering is easy to forget until the day it is needed. Keep one printed copy of the photograph set with your poultry records, so a house-sitter can hand the comparison pictures to a finder without needing access to your phone.
What to ask the person who found a barred hen
Ask a finder to photograph the bird's left side and feet and to read you the band number before either of you concludes anything, then compare the bar width on the breast and the comb points against your set. Mention that Plymouth Rocks are calm, heavy hens that usually settle rather than fly, so she can likely be cornered gently into a box instead of chased, which protects the very feathers everyone is trying to match. Storing the photographs, the barring notes and the band number together in KinsLe through her Verified QR ID Pet Profiles means the scan a finder makes at the fence opens the exact comparison set, not a stranger's memory of a striped chicken.