Yes. A red-eyed tree frog spends the day pressed flat against the underside of a leaf, pale green, eyes tucked away, deliberately looking like nothing at all. Judging its health from daytime observation is nearly pointless. Everything that matters, feeding, movement, hydration, colour at full intensity, happens at night, and a log is how those night hours become information you keep rather than impressions you lose by morning.
What a healthy night looks like on paper
After lights-out, a thriving frog wakes, colours deepen, the red eyes open fully, and it begins deliberate hunting, tracking insects and striking with accuracy. It should move between perches with firm grip, soak or sit in its water source at times, and return to a sleeping leaf before morning. Entries describing that sequence, even briefly, establish the frog's personal normal, which varies enough between individuals that your written version beats any general description.
Weight plays a supporting role. These frogs are light and delicate, and frequent handling risks skin damage and stress, so weigh occasionally in a damp, tared container, perhaps every month or two, and treat body condition, a rounded but not bloated abdomen, no sharp hip bones, as the everyday measure.
Writing entries that capture the right things
Log after the evening feed, while the night's events are fresh. Record how many insects were offered and how many were struck at and caught, since a frog that lunges and misses repeatedly is telling you something different from one that ignores food entirely. Note posture on waking, colour intensity, any time spent on the enclosure floor, which is unusual for this strongly arboreal species, and whether the skin looked well hydrated or dry and tight.
Add the conditions behind the behaviour: misting schedule, humidity range, temperature after dark, and any new plants or rearranged perches. Red-eyed tree frogs respond quickly to drying air, and an entry that pairs a dull night with a failed mister explains itself weeks later when you reread it.
Signals that should not wait for the next entry
Flag a frog that stays on the floor, sleeps in exposed spots rather than under a leaf, misses strikes repeatedly, or shows reddened skin on the legs or belly, sores, or a bloated, waterlogged look. Incomplete sheds that leave skin clinging, or a frog found awake and dull during the day, also belong in the log in plain words with the date, because timing is diagnostic in a species that can change quickly.
Several poor nights in a row, especially with falling interest in food, justify an amphibian-experienced veterinarian, and your dated night entries, which show the sequence rather than a single bad evening, give that consultation real substance.
Keeping night notes from scattering
The practical risk with this species is not failing to observe; it is observing at midnight and writing nothing durable by morning. Keep the log beside the enclosure or in the same place you record misting, and accept short entries. Three honest lines a night, several nights a week, build a record no memory can match for an animal whose life happens in the dark.
Those lines deserve a permanent home, and KinsLe's Pet Passport provides one for your red-eyed tree frog, holding its feeding, posture, and condition notes together in a portable packet ready for a vet visit.