Generally over a course of two months during the fall, hundreds of rough-skinned newts (Tarichagranulosa) try to cross Mt. Constitution Rd. on their way from summer breeding ponds to forested winter foraging areas. Far too many are squashed by unaware motorists and bikers, leaving telltale ribbons of newt-shaped stains on the asphalt. Watch for the special newt crossing signs that will be posted on the road during migrations!
Only female newts appear to migrate in the islands. The males remain behind in home lakes and ponds and await the females’ return in spring
when water levels begin to drop and its time to breed. They lay their eggs one at a time over several days. Breeding can occur from late April to July.
These orange-bellied newts are one of the islands’ two most abundant amphibians (the other is the tiny Pacific chorus or tree frog, Pseudacris regilla).
They are most amazing animals. If you approach a newt, it may rear up and display its orange belly—a warning of toxicity. Or it may play dead, absolutely stiff. When it believes the coast is clear, it will make a sudden dash for safety!
Rough-skinned newts exude a very powerful neurotoxin, tetrodotoxin, from their skin and are best handled with gloves. One predator has evolved the ability to tolerate significant amounts of tetrodotoxin—the common garter snake (Thanophis sirtalis), also abundant in the San Juan Islands. In fact, eating newts confers protective toxicity on the snake! There is also evidence that the snakes “taste” each newt they catch and reject exceptionally toxic ones.
Genetic evidence indicates that rough-skinned newts spread north into the Salish Sea from northern California and Oregon after the retreat of the last continental glaciers, less than 10,000 years ago. They probably made their way to the San Juan Islands even more recently, and it is quite possible that our island newts are genetically distinct from mainland newts, and better adapted to our relatively dry “rain shadow” climate.
So please drive carefully! And if you have newts on your property, enjoy their aquatic antics without disturbing them or
introducing non-native predators.
You can see newt migrations around Summit Lake in Moran State Park. Please respect the newts and observe safe observations by not touching the Newts!
Friends of Moran would like to thank Russel Barsh and Madrona Murphy who live on Lopez and are conducting biodiversity surveys for the local nonprofit conservation laboratory, Kwiáht. We’d also like to thank Shelly Kinner for helping us write up this fascinating info.