The Diversity of Other Terrestrial Fauna on Príncipe Island

Beyond the Birds: Príncipe's Hidden Endemic Fauna

Beyond its celebrated endemic birds, Príncipe supports exceptionally high endemism in land snails (60-78%), amphibians (100%), reptiles (70-80%), and its sole native terrestrial mammal (100%). These percentages rank among the highest for any island system globally, testament to millions of years of evolutionary isolation.

When most visitors think of Príncipe's wildlife, endemic birds immediately come to mind—and rightly so. But look closer, and you'll discover that 31 million years of isolation has produced evolutionary marvels across nearly every branch of the animal kingdom. From giant land snails that dwarf your fist to Africa's largest tree frog, from legless skinks that "swim" through forest soil to geckos the size of your hand, Príncipe harbors a secret menagerie of unique species that most travelers never encounter.

These are the quiet endemics—creatures that don't announce themselves with brilliant plumage or distinctive calls, but reveal themselves only to those who know where to look and take time to observe. For naturalists willing to venture beyond the obvious, Príncipe offers encounters with some of the world's most unusual and threatened invertebrates and small vertebrates.

The Giant Land Snails: Príncipe's Slow-Motion Giants

Most people don't travel for snails. But Príncipe's terrestrial mollusks tell one of the island's most compelling evolutionary stories. The land-snail fauna of the Gulf of Guinea oceanic islands is highly distinctive, and Príncipe harbors 40-45 terrestrial species (excluding coastal forms) with jaw-dropping endemism rates between 60-78%. At least 24 species exist nowhere else on Earth, and recent surveys continue discovering species entirely new to science.

The Obô Giant Land Snail: An Icon in Crisis

The crown jewel of Príncipe's mollusk fauna is the Obô Giant Land Snail (Archachatina bicarinata), shared only with São Tomé. With shells reaching 11.7-15.7 centimeters in length—roughly the size of your palm—this herbivorous giant plays a crucial role in forest litter decomposition. Unlike most African giant snails, which are strictly nocturnal, the Obô Giant is unusually active during daylight hours, making observation possible for patient visitors.

The species carries both ecological and cultural significance. Local communities have historically harvested these snails for food and traditional medicine, and they remain important in island culture. But this cultural value has contributed to their decline.

The Obô Giant Land Snail was formerly widespread and locally abundant across Príncipe. Then came catastrophe. Since the 1990s, populations have collapsed by approximately 75% during the first two decades of the 21st century, with their range contracting by about 40%. Today, they're largely confined to remote, high-elevation native forest in the south, with an estimated Area of Occupancy of just 65 km²—an area smaller than Manhattan.

What happened? The perfect storm of threats: overharvesting for traditional uses, habitat degradation as forests fell to agriculture, and perhaps most insidiously, competition and potential pathogen transmission from the introduced West African Giant Snail (Archachatina marginata). This invasive relative, brought to the island by humans, may be outcompeting or infecting its native cousin. The IUCN now classifies the Obô Giant Land Snail as Endangered—a species racing toward extinction unless urgent action reverses current trends.

For visitors: Finding Obô Giant Land Snails requires hiking into the southern high-elevation forests of Príncipe Natural Park, preferably during or shortly after rain when they're most active. Look on tree trunks, under leaf litter, and on wet vegetation. Never collect or disturb snails you encounter—every individual matters for this declining species.

The Herpetofauna: A Reptile and Amphibian Paradise

Príncipe and its satellite islets host 17 readily distinguishable amphibian and terrestrial reptile taxa—an impressive diversity for such a small island. Across the São Tomé and Príncipe archipelago, all nine amphibian species and approximately 17-18 of the 21-22 terrestrial reptile species are endemic. This near-total endemism is extraordinary for any island system.

The Amphibians: Three Frogs, Three Stories

The fact that amphibians exist on Príncipe at all is remarkable. As animals with permeable skin vulnerable to saltwater, amphibians rarely colonize oceanic islands naturally. Their presence suggests ancient colonization events followed by millions of years of evolution in isolation. All three of Príncipe's amphibians are endemic—an unusual situation that makes every frog sighting significant.

Príncipe Giant Tree Frog (Leptopelis palmatus)

This is the superstar you're most likely to encounter, and what an encounter it is. The Príncipe Giant Tree Frog holds the title of Africa's largest arboreal anuran, with females reaching 81-110 mm snout-vent length—nearly four and a half inches of frog clinging to branches in the island's forests.

Drewes' Reed Frog (Hyperolius drewesi)

Described to science only in 2016, this recently recognized endemic remains something of a mystery. Sexually monochromatic—meaning males and females share the same green coloration—this small reed frog occupies wetland habitats across the island.

Príncipe Puddle Frog (Phrynobatrachus dispar)

The most adaptable of Príncipe's amphibians, the Puddle Frog occurs from sea level all the way to the summit of Pico do Príncipe at 948 meters. Shared with São Tomé, this endemic tolerates a wide range of habitats and maintains stable populations, earning it a Least Concern classification.

The Reptiles: Geckos, Skinks, and Snakes of Distinction

Príncipe hosts 13-14 terrestrial reptile taxa, with approximately 70-80% endemism—among the highest rates for any island reptile fauna globally. Several single-island endemics deserve special attention.

Príncipe Gecko (Hemidactylus principensis)

This recently described gecko is a large species—noticeably bigger than the house geckos familiar to most tropical travelers. Unlike its introduced relatives that colonize human buildings, the Príncipe Gecko maintains its wild nature, typically found on tree trunks and rock outcrops in forested areas. It actively avoids human dwellings, making encounters a sign you've entered genuine wilderness.

Look for these impressive geckos during night walks, when their reflective eyes shine back in flashlight beams. Their size and reluctance to flee make them excellent subjects for observation and photography.

Príncipe Legless Skink (Feylinia polylepis)

Here's where Príncipe's evolutionary experiments become truly bizarre. The Príncipe Legless Skink represents an extreme case of island-driven morphological adaptation—a lizard that has completely lost its limbs and evolved into a fossorial (soil-dwelling) creature that "swims" through loose forest floor substrate.

This species rarely surfaces, spending most of its life underground hunting small invertebrates in the leaf litter and soil. Its snake-like appearance often causes confusion, but close examination reveals the subtle features that mark it as a highly modified skink: vestigial limb girdles, eyelids that blink (snakes lack movable eyelids), and external ear openings.

For visitors: You're extremely unlikely to see this species without dedicated searching. It occasionally appears after heavy rains when soil flooding forces it to the surface, but remains one of Príncipe's most elusive endemics.

Other Endemic Reptiles

The blind snake Typhlops elegans and the green tree snake Hapsidophrys principis round out the endemic reptile roster. The latter, a beautiful arboreal serpent, occasionally appears during forest walks, its brilliant green coloration providing camouflage among leaves.

The Terrestrial Mammals: Bats and a Mysterious Shrew

Native non-marine mammal diversity on Príncipe is extremely low—unsurprising for an oceanic island. The fauna consists almost entirely of bats, with four species present and a 50% endemism rate. These flying mammals colonized the island across ocean gaps that terrestrial mammals couldn't cross.

The Príncipe White-toothed Shrew: An Enigma

The only native non-flying terrestrial mammal deserves an award for elusiveness. The Príncipe White-toothed Shrew (Crocidura fingui) was described relatively recently based on molecular and morphological evidence that proved it distinct from continental African shrews. Scientists have confirmed it from only four localities in the northern part of the island, with a single camera-trap record from Pico do Príncipe.

Think about that: in the age of satellite imagery, GPS tracking, and environmental DNA analysis, we have just five documented locations for Príncipe's only native terrestrial mammal. Its current IUCN status—Data Deficient—reflects profound ignorance about its distribution, population size, and ecology.

What threatens this mysterious mammal? Potentially introduced predators like rats and cats, competition from the introduced Asian House Shrew, and habitat loss. But we don't know for certain because the species remains so poorly studied.

For visitors: You almost certainly won't see this shrew unless you're conducting systematic mammal surveys with camera traps and live traps. But knowing it exists—this tiny endemic mammal scurrying through the forest floor, largely unknown to science—adds another layer of mystery to Príncipe's forests.