A chick that is falling behind rarely announces it — it just gets gradually smaller than its penmates until the gap is obvious and harder to close. A simple weekly record of weight and feathering catches that drift while it is still a feeding problem rather than a health one, and it takes only minutes per bird once the routine is set.
What to write down each week
Weigh every chick on the same day each week, on a small digital scale with a tub or cup for it to stand in, and record the weight beside the chick's identifier. Note feathering in stages rather than impressions: wing feathers through, tail sprouting, back and breast covered, head last. Add one line for anything unusual — a chick that is empty-cropped at feeding time, one that gets pushed off the feeder, droppings that look wrong. A phone photograph taken from the same angle each week is worth more than adjectives: laid side by side, four weekly pictures show a growth curve your eye can read at a glance.
Make sure the record belongs to the right chick
Records only work if each line follows the same bird. Coloured leg bands sized for growing chicks, replaced as legs thicken, are the simplest identifier in a mixed brooder; in small batches, a dab of livestock marker on different parts of the down does the same job. Write the band colour in the notebook on the first day it goes on. If you hatch or buy in groups of different ages, keep their records in separate sections — comparing a chick with its own hatchmates is the whole point, and a younger bird weighed against older ones will look like a failure when it is not one.
Reading the record: what 'slow' actually looks like
A slow developer shows up in the pattern, not in a single reading. Look for a chick whose weekly gain flattens while its hatchmates keep climbing, or whose feathering sits a full stage behind the group — still mostly down along the back when the others are feathered over, for instance. One light weighing after a hot day means little; two consecutive flat weeks mean the chick is not converting feed the way the rest are. Feathering that lags while weight holds up can point to a bird being kept away from the feeder at peak times rather than one that cannot eat.
Acting on what the record shows
Move a flagged chick to a smaller group or a quiet pen with its own feeder and drinker, where it can eat without competition, and weigh it twice a week until its curve bends back up. Offer the same starter feed, check that its vent is clean, and feel whether its crop fills during the day and empties overnight. If a chick loses weight, stays hunched and fluffed with closed eyes, or does not respond within a couple of days of unhurried feeding, that is beyond a record-keeping problem — a vet who treats poultry should see it, and your dated weights will tell them far more than a summary of 'not growing'.
Storing each chick's weights and feathering notes in its KinsLe Pet Passport keeps the whole growth record in one portable packet, ready to hand to the bird's next keeper or open at the vet's table.