Alaska is the only state in the United States that has no native snake species. This is quite remarkable considering Alaska’s immense size and diverse geography. So why are there no snakes in Alaska?
The Friozen North
The main reason there are no snakes in Alaska is because of the climate. Alaska is extremely cold for much of the year, with average temperatures below freezing for 6-8 months. This frigid environment is simply too inhospitable for reptiles like snakes to survive.
Snakes are cold-blooded, meaning they rely on external temperatures to regulate their body temperature. When it gets extremely cold, snakes enter a state of brumation where their metabolism slows down dramatically. But the sub-zero winter temperatures in Alaska dip too low, for too long, for brumation to be a viable survival strategy.
Most snake species cannot survive more than a few days at temperatures below freezing. Alaska’s average winter temperatures often drop to -20°F (-29°C) or colder. Only the southern and coastal regions of Alaska experience milder winters with temperatures closer to freezing.
But even during the summer months, Alaska is too chilly for snakes. The average summer temperature statewide is just 52-60°F (11-16°C). Snakes thrive at temperatures above 70°F (21°C) when they can be active predators. Simply put, it’s just too cold year-round in Alaska for snakes to survive.
Isolation
In addition to the climate, Alaska’s geographic isolation also helps explain the lack of snakes. Alaska is separated from the contiguous United States by the vast Canadian province of British Columbia. There are no native snake species this far north on the North American continent.
For snakes to reach Alaska, they would have had to gradually spread northward as the climate warmed following the last ice age. But there are major geographic barriers that likely prevented their expansion that far north.
The Rocky Mountains and other mountain ranges in northwest Canada prevent easy migration routes from the western continental U.S. into Alaska. And there are no snake species native to northern Canada east of Alaska either.
With thousands of miles of inhospitable terrain and cold climates separating it from areas with snake populations, Alaska simply remained too isolated for snakes to ever colonize it.
Could Snakes Move to Alaska in the Future?
Climate change is warming Alaska faster than the continental U.S., which raises the question – could snakes eventually spread to Alaska? While it’s possible, there are still major challenges for snakes to overcome:
- Average annual temperatures would need to increase significantly before snakes could survive year-round.
- The remoteness and isolation still acts as a barrier to snake migration routes.
- Snake habitat and food sources are still very limited in much of Alaska.
- Humans likely would not allow non-native snakes to become established due to ecological impacts.
So while global warming may allow reptiles to gradually spread further north, the conditions needed for snakes to thrive and reproduce are still a long way off in Alaska.
A Snake-Free Ecosystem
The absence of snakes has contributed to some unique aspects of Alaska’s ecosystems:
- Animal populations like small rodents and birds do not need to defend against snake predation.
- Other predators like raptors, foxes, and lynx fill the niche occupied by snakes further south.
- Some mammals in Alaska undergo deep hibernation in winter, a strategy that would be risky with snakes around as potential predators.
- Humans in Alaska don’t need to be wary of accidental snake encounters in the backcountry.
So while snakes play important roles as both predator and prey in most continental ecosystems, Alaska’s ecosystems have adapted and evolved in their absence.
Alaska’s One Exception
There is one snake that has managed to establish a tiny foothold in Alaska – the Common Garter Snake. But it’s only found way down south in the temperate rainforests of the Alaska Panhandle near the coast.
A small garter snake population exists on the border between Alaska and British Columbia. It’s likely this is a northward extension of a British Columbian snake population that found the mild maritime climate of southeast Alaska just barely habitable.
But the Common Garter Snake’s range only extends about 16 miles into Alaska at its greatest extent. And the population remains small and highly localized, showing just how limiting the climate is even for this cold-tolerant snake species.
Prehistoric Snakes
Interestingly, Alaska was not always snake free. Fossil evidence shows that snakes did once live in Alaska when the climate was warmer:
- 60-million-year-old snake fossils found on the North Slope from the late Paleocene era.
- Boas andPythons present during the Miocene era 5-23 million years ago.
- Warm climate species like Vipers and Colubrids during the late Miocene through Pliocene 1-5 million years ago.
But as the Pleistocene Ice Age set in and glaciers advanced, the climate became too inhospitable for snakes to survive in Alaska. By the time the glaciers retreated and the climate warmed again, snakes simply could not recolonize the isolated northern region.
So while prehistoric snakes once thrived in Alaska’s warmer ecosystems, the current cold climate and geographic barriers prevent snakes from moving back in today.
The Future of Snakes in Alaska
Looking ahead, it seems unlikely snakes will naturally colonize Alaska anytime soon. Some key reasons why:
- Climate change, while warming Alaska faster than the lower 48 states, is still not making the region warm enough for snakes year-round.
- Snakes have no migration route to move northward into the remote state naturally.
- Introducing non-native snake species would have negative ecological consequences.
However, small snake populations could potentially gain footholds in the warmest southern parts of Alaska as rare outliers. Any snake inhabiting Alaska would need to be cold-tolerant and live near the southern coasts. If temperatures continue to rise faster in the north, snakes may gradually expand their ranges incrementally closer to Alaska.
But a full-scale snake invasion of Alaska remains very unlikely. The climate is likely to remain too harsh and the isolation too limiting for snakes to ever thrive statewide. This frozen state will likely retain its unique snake-free status for the foreseeable future.
Conclusion
In summary, the main reasons why Alaska has no native snake species are:
- The freezing cold climate makes it impossible for snakes to survive the winters.
- Alaska’s isolation from other habitats prevents colonization by migrating snakes.
- The short, cool summers still don’t provide ideal conditions for snakes.
- Geographic barriers like mountains further limit access for snakes.
- Prehistoric snakes did once live in Alaska but went extinct with the Ice Age.
- Climate change today is still not making Alaska warm enough for snakes to easily colonize.
So don’t worry about snakes slithering through the Alaskan wilderness anytime soon. The Last Frontier is likely to remain serpent free well into the future thanks to its northern latitude and geographic isolation. Just one of the many things that makes Alaska so unique!