By LISSA STROHECKER
Maui Invasive Species Committee
From the chirping of a house gecko snapping at insects at the window to the flash of color on the porch as a gold dust day gecko scurries by, lizards are ubiquitous near homes and gardens in Hawaii. Hawaii is now home to 18 species of geckos, skinks and chameleons. Because they have tropical jewel status, scientists have not paid them much attention. Half of them have arrived since 1950, most in the past few decades, hitchhiking on landscaping materials or escaping the pet trade. It is generally believed that these lizards did not make it to the islands on their own—that’s too far for something without wings or fins.
Of these eighteen reptiles that neither fly nor swim, three skinks have been native to Hawaii for hundreds of years. “Excavations and records of Western explorers show that they were here before contact with the West,” says Valentina Alvarez. She wrote her doctoral thesis at the University of Hawaii on the genetics of these lizards.
Hawaiian stories and olelo (sayings) refer to mo’o lizards. Since these three types of skink are also common elsewhere in the Pacific, scientists assumed that they came here with the Polynesians in canoes along with ulu and coconuts, chickens and dogs.
But based on decades of observations by her colleagues, Alvarez suspects that in the millions of years that the Hawaiian archipelago has existed, a particularly resilient skink may have washed here on debris and survived because it was adapted to life on the coast. “Here and there there is little evidence,” Alvarez says: “but the strongest evidence lies in the genetics of the lizards.”
The snake-eyed skinks found in Hawaii belong to an ancient lineage and are different from other populations of this species in the Pacific, she explains. The differences suggest that the snake-eyed skinks may have arrived in Hawaii tens of thousands or even millions of years ago. “This is not the pattern of the other two skinks that were there before contact with the West,” Alvarez says: “These other two skinks are genetically very similar to existing populations elsewhere in the Pacific.”
The snake-eyed skink, scientific name Cryptoblepharus poecilopleurus, also fits the profile of a potential pioneer. Alvarez says evidence suggests it can tolerate salt water. The skink is adapted to life on salt-sprayed coasts and in hot, rocky habitats and has the physical capabilities to survive a sea voyage. The genus also has a success story: Close relatives of the snake-eyed skink have made it to other remote islands in the Polynesian Triangle (defined by the three island groups at its corners – Hawaii, Rapa Nui (Easter Island) and Aotearoa (New Zealand)). “A subspecies of this lizard on Rapa Nui is said to have colonized the island naturally. Like Hawaii, Rapa Nui is extremely remote,” she explains.
To find more evidence, Alvarez is taking a closer look at genetics across the Pacific to see if she can narrow down the snake-eyed skink’s possible arrival dateline. “We will see if we can make this distinction to determine whether the snake-eyed skink was there before the arrival of the first humans,” she says.
One challenge today is to find skinks. In addition to the other “Canoe Lizards” (the Blue-tailed Skink and the Moth Skink) Populations of the Snake-eyed Skink are shrinking. In the 1840s, Western explorers declared them “as common as leaves on a tree.” Now Alvarez is having trouble finding her. “The populations are very fragmented and when I find them, they are only present in small numbers.” On a stretch of beach that would provide suitable habitat, she might find three or four. “I have never met anyone who has seen a lizard like this and is not already interested in lizards.” The cause of their decline is probably a combination of disturbance, invasive species such as ants, and competition from introduced lizards.
The strongest populations live far from humans. The island of Laysan in northwest Hawaii and a small island off the coast of Oahu are two of the few places where snake-eyed skinks thrive. Otherwise, only a handful of scattered populations of these ancient lizards remain.
You can help us learn more about the snake-eyed skink – Hawaii’s first lizards. Alvarez relies on iNaturalist, the online citizen science platform, to find lizard populations. If you’re exploring a rocky shoreline and see a dark-colored skink speckled with gold, try taking a photo and sharing it through iNaturalist.com. The lizard is shy, but Alvarez says it will return if it waits quietly. Reporting other lizard species through the iNaturalist platform can also help researchers find and track their distribution and spread.
As always, snake reports should be forwarded to 911 for immediate response. Illegal reptiles can be surrendered without penalty through the Hawaii Department of Agriculture’s amnesty program – no questions asked.
* Lissa Strohecker is the public relations and education specialist for the Maui Invasive Species Committee. She holds a degree in biological sciences from Montana State University. Kia’i Moku, “Guarding the Island”, is produced by the Maui Invasive Species Committee to provide information to protect the island from invasive plants and animals that can threaten the island’s environment, economy and quality of life.
