It's Kaloula pulchra and it's an interesting observation because the species is not often found on trees. Other species within the genus (K. borealis) also climbs trees in fall, for unknown reasons (see link below), and other species preferentially live on trees ( Blackburn et al. 2013. Evolution 67:2631–2646). If it's a (natural) recurrent observation it could be interesting to think about a natural history note to report the behaviour.