Arboreal habitats provide expanded niches for species by offering access to new food sources and providing safety from predators. To securely navigate these challenging 3-D environments, treefrogs generate gripping forces using both active muscle recruitment and passive mucus adhesion mechanisms to maintain contact with the substrate and prevent falling. This study focused on Australian Green Treefrogs (Ranoidea caerulea) as a model for exploring grasping abilities in an arboreal context. Using a portable grip strength tester, we collected pulling forces from five animals (mean body mass: 34.1 ± 7.6 g) across five different substrate diameters (2.5, 5.0, 7.5, 10.0, and 12.5 mm). Our findings revealed that mucus adhesion accounts for approximately 75% of pulling forces, as indicated by a significant reduction in force when using an oiled substrate. Additionally, hindlimbs exhibit greater pulling forces than forelimbs, which is consistent with the larger size and primary propulsive function of hindlimbs in anurans. We also observed a decrease in force generation on larger diameter substrates, which was likely due to length-tension properties of the flexor musculature. Comparisons with other arboreal species demonstrated that treefrogs exhibit similar relative pulling strengths. Mucus adhesion represents a crucial mechanism facilitating movement on arboreal supports, allowing amphibians to navigate arboreal substrates without extensive anatomical adaptations. Further comparative studies across diverse anuran taxa are needed to explore the role of hindlimb morphology in grasping adaptations. Understanding the interplay between active muscle recruitment and mucus adhesion mechanisms will provide valuable insights on evolution of grasping abilities in arboreal tetrapods.

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