 |
| Palawan Splash Frog |
The Palawan Splash Frog (Staurois nubilus), also known as the Palawan Rock Frog, is a species of true frog in the family Ranidae, endemic to Palawan. Four ranid frogs are known to inhabit Palawan: the Nicobar Cricket Frog, Palawan Stream Frog, Palawan Torrent Frog, and Palawan Splash Frog. Among these, the Palawan Splash Frog, or Palawan Rock Frog, is considered the most abundant. Since its original description as Ixalus nubilus by Mocquard in 1890, the species has undergone multiple taxonomic reassignments and subsequent revisions. Today, it is recognized for its unique placement within the Staurois genus, a group of frogs renowned for inhabiting rocky torrents and utilizing unique foot-flagging behaviors for communication.
 |
| Palawan Splash Frog |
Staurois nubilus possesses the slender body form and elongated limbs characteristic of its genus, which are perfectly adapted for climbing and leaping across wet, rocky terrain. Its dorsal skin is covered in granulated tubercles of varying sizes, providing a textured surface that likely aids in camouflage and traction. The fingers of Staurois nubilus are either entirely unwebbed or have only minimal webbing, which aids in climbing vegetation. In contrast, its toes are fully webbed, allowing for strong propulsion while swimming. Its toe pads have superior adhesion compared to other amphibians to slick, wet, smooth surfaces like water-polished rocks and glabrous leaves.
 |
| Palawan Splash Frog |
This species is strictly tied to rocky streams with clear, flowing water within Palawan’s primary and secondary lowland forests up to small, fast-flowing streams on mountain slopes. Within these ecosystems, adult frogs can typically be found actively on the ground around the banks and streambed during the day. At night, it can be found perched on overhanging leaves and twigs around the streams or on top of larger rocks in the riverbed and boulders lining the banks. Staurois nubilus mates in stream habitats, typically on wet rocks or cascades, and it is known to lay eggs and undergo larval development in clear water.
 |
| Palawan Splash Frog |
To survive in swift torrent environments without being swept away, Rock Frogs have evolved specialized morphological traits for clinging to slippery substrates. A study of its close relative Staurois parvus from Borneo shows that a key feature of its toe pads is the presence of straightened channels between the epithelial cells. These channels rapidly drain excess water, maximizing direct contact and friction against wet rocks. It was also observed in Staurois nubilus that when navigating particularly steep or overhanging surfaces where toe pads alone might fail, the frog employs a whole-body attachment strategy by pressing its belly and thigh skin against the rock to increase surface area and stability. These enable agile leaping and secure positioning amidst flowing water.
 |
| Palawan Splash Frog |
The Palawan Splash Frog distribution in mainland Palawan is wide, with confirmed presence in many mountain ranges in central and southern Palawan, including Cleopatra's Needle, Thumb Peak and the surrounding area, Mount Victoria, Mount Gantung, and Mount Mantalingahan. It has also been recorded in the islands of Busuanga and Culion, and we saw it during a herping trip in Dumaran a few years back. Although the population is very sparse in Palawan lowland areas, this species is possibly the first amphibian that you will encounter once you're in the streams at the foothills. They're very active during the day and hard to miss.
 |
| Palawan Splash Frog |
According to the IUCN Red List assessment published in 2017, Staurois nubilus is classified as Near Threatened (NT), with an overall declining population trend despite being locally abundant in certain undisturbed areas. The primary driver of this decline is the loss and degradation of lowland forests and stream systems across Palawan. The species avoids stagnant or muddy waters. Logging, wood harvesting for charcoal, and agricultural expansion, including small-scale farming and large plantations next to rivers, consistently shrink and pollute its viable habitat with agricultural runoff. Furthermore, mining operations, such as nickel, chromite, and quarrying, severely impact the ecosystem by causing stream sedimentation, erosion, and chemical pollution from mine tailings.
 |
| Palawan Splash Frog |
The Palawan Splash Frog is one of the most common frogs in Palawan, and the impact on this species is not too visible yet. The species is abundant in all major mountain ranges in Palawan and is common around rivers and streams at the foothills and mountains where it occurs. However, ongoing habitat degradation poses a significant long‑term threat. Although its remaining populations seem stable, continued loss of pristine riparian habitats may lead to localized declines, particularly in areas where forest cover is fragmented.
 |
| Palawan Splash Frog |
As an endemic species, Staurois nubilus plays an important ecological role in Palawan’s freshwater ecosystems, serving both as a predator of invertebrates and as prey for larger vertebrates. Its abundance makes it a key indicator of stream health, and its survival is closely tied to the preservation of intact forested watersheds. If habitat degradation accelerates, the species may face population contractions, reducing its ecological resilience and diminishing its role in maintaining stream biodiversity.
 |
| Palawan Splash Frog |
The Palawan Splash Frog is still one of the most frequently encountered endemic amphibians in Palawan, possibly second only to the Philippine Toad. However, the future population of this endemic species depends on effective conservation not just of our old-growth forests but also on the protection of riparian zones, sustainable land-use practices, and monitoring of stream quality. Safeguarding this frog is not only vital for maintaining Palawan’s unique amphibian diversity but also for preserving the integrity of its freshwater ecosystems.
