Yes — keep one, but never as a single mixed list, because Muscovy ducks break the usual duck expectations: drakes mature far larger and heavier than hens, and a log that averages them together makes the hens look stunted and the drakes look alarming when both are perfectly normal. Tracked bird by bird, the record becomes genuinely useful for a quiet, self-reliant breed whose members often keep foraging and sitting long after something has started to go wrong.
Compare each Muscovy only with itself
Weigh on a platform the bird can stand on calmly, or assess condition by feeling the breast muscle around the keel, and record which method you used so later entries stay comparable. For a drake, note his mobility as carefully as his weight: a big male who becomes reluctant to walk, rests on his breast more, or struggles to keep up with the flock is telling you something a scale alone would miss.
For hens, the log's most revealing stretch is brooding. A Muscovy hen commits to the nest for a long sit and may leave it only briefly to eat and drink, emerging noticeably lighter. Writing down her starting condition, how she looks midway, and whether she is still coming off to feed lets you judge whether the sit is costing a normal amount or too much.
Daily-life details worth capturing
Muscovies are comparatively quiet and spend much of the day grazing and working over the ground for insects, so changes in that routine stand out in writing. Note a bird who stops joining the group's slow circuit, spends the day apart under shelter, or leaves feed untouched. Record the state of the red facial caruncles and eyes, droppings, and any limping or splayed resting posture, since heavy waterfowl put real load through their legs and feet.
Because Muscovies fly better than most domestic ducks, also note wing condition and any bird who suddenly stops roosting up where she usually sleeps — a small behavioral line that can flag weakness before weight moves.
Acting on what the log shows
Look for the individual trend: a drake gaining steadily while his walking worsens needs a feed and space review and veterinary input if the gait does not improve, while a hen still losing condition well after her ducklings are moving about needs closer support and advice rather than patience. Sudden appetite loss, discharge around the eyes or nostrils, or a bird unable to rise should move you to prompt veterinary help and separation from the flock while you observe intake.
The log also settles arguments with memory at sale, breeding, or rehoming time, when an honest growth history for a young drake is worth more than a confident guess. If you keep several Muscovies, a simple mark or leg band noted in the log prevents the classic mix-up of crediting a thriving drake's weight to a hen who is quietly doing worse than her entry suggests. When young birds are growing, log them more often than settled adults, because a juvenile who stalls for two checks in a row deserves a look at feeder access long before the difference is obvious across the yard.
Keeping each Muscovy's weights, breast checks, and brooding notes in KinsLe with Pet Passport holds every bird's separate story together in one packet for vet visits and new keepers.