Night is when a tree frog's joints file their report
A green tree frog spends his days sleeping and still, so judge an aging green tree frog only by his nights, when he should be climbing, hunting and jumping. Joint discomfort shortens those night jumps first: leaps between leaves become single steps, and crossings he once made in one jump become a climb down and a climb up. He may crouch facing a target leaf for a long moment, then turn away from the jump altogether. An aging tree frog who relocates his whole night to one low corner, feeding only on what passes there, has shrunk his world in the way sore hips and shoulders shrink it.
Sleeping lower is the change owners actually see
Most keepers notice an aging green tree frog's sleeping spot before his gait, because the daytime perch is easy to check. A frog who slept for years pressed high on the glass or folded on a top leaf, and now sleeps at plant-pot height night after night, is avoiding two climbs a day. His fingers may rest splayed and flat rather than curled to grip, and a hind leg may stretch out behind him instead of folding neatly under his body. Photograph the perch weekly from outside the glass; a slow downward migration over a season is exactly the evidence that memory alone smooths away.
Leg extension and the frog's landing gear
When an aging green tree frog does jump, watch the machinery in slow moments: both hind legs should extend together and land him squarely. A frog favouring one side lands twisted, scrabbles with the front feet, or lets the weaker hind leg trail against the leaf. Climbing shows the same asymmetry more gently, with one back foot placed late or set down without gripping. A leg that trembles through a climb, or fingers that will not close on a stem they held last month, belong in the notes. Wet skin and smooth glass can make any frog slip, so judge landings on leaves and bark, not on misted glass.
Keeping his nights reachable
Rearrange an aging green tree frog's enclosure so his night route is a ladder of broad leaves and cork, each step a short hop rather than a leap, with his water dish on the floor he now prefers. A second shallow dish on a low shelf means hydration never depends on the climb he is avoiding, and feeding with tongs near his chosen corner keeps his weight up while you observe. Keep humidity steady, because a drying frog moves badly for reasons unrelated to joints, and note the readings beside your movement notes. Dim red light lets you watch a full night shift without freezing him mid-climb under a bright torch.
When a tree frog's change is a vet matter
An exotic vet should see an aging green tree frog who stops jumping entirely, who cannot grip with a foot, or whose leg joint looks swollen against its twin. A leg held permanently extended or folded, toes that darken, failure to right himself after a fall, or appetite loss joining the lower perches all shorten the timeline to days. Take perch photographs, night notes and humidity records, because a frog's stiffness has several possible explanations the vet must work through. Filed in KinsLe's Pet Passport, those weekly perch photos make a slow decline impossible to mistake.