Alaska Herpetological Society
Invasive species are a true concern in Alaska since these have the potential of causing harm to native amphibian populations through competition and disease. While some species may arrive in Alaska naturally as a result of natural range expansions, many are the result of human activities, both intentional and unintentional. Several common pathways of arrival include:
- The release of pets that are no longer wanted or that can no longer be cared for
- The unintentional escape of pets from their enclosures
- The release of animals that people think would be "cool" to have in Alaska
- The release of classroom pets and educational aids at the end of the school year
- Arrival with cargo shipments via road, sea, and air
These human-assisted pathways for species introductions are likely to increase over time as Alaska's human population increases and the shipment of goods increases. Unfortunately, projected climate scenarios suggest an increase in favorable conditions under which some species may successfully over-winter in Alaska and even establish viable populations. Two species that were intentionally (and illegally) introduced in Alaska and which have established populations are the Red-legged Frog and the Pacific Chorus Frog.
And its not just amphibian and reptile introductions that can harm our native herpetofauna! Some species of fish, particularly pike and trout, have been known to cause devastating declines in amphibians when introduced to a system. Pike were introduced in Southcentral Alaska in the 1950s and have since spread throughout much of the region. Though they are native to more northerly parts of Alaska, species in their native range have had hundreds if not thousands of years to adapt to the presence of this voracious predator.
This invasive Northern Pike was found with six Wood Frogs in its stomach. It was caught in Alexander Creek, AK and photographed by Samuel Ivey of the Alaska Department of Fish and Game.
As mentioned, two species of amphibian that were introduced intentionally in Alaska have established viable populations. The Red-legged Frog is now prevalent throughout much of Chichagof Island and was the result a K-12 teacher disposing of unwanted classroom pets in 1982. Local knowledge suggests that native amphibian populations have declined drastically in the area, and it is possible that this is in part due to the introduction.
The Pacific Chorus Frog was introduced around 1960 when a resident of Ketchikan dumped a bucket of amphibian eggs into a pond that he flew back from Washington State in his personal plane. These eggs were dumped into what is now called "Frog Pond" near Ward Lake on Revillagigedo Island. The population at this site is stable, but as of 1992 they did not seem to have spread to other areas of the island. That said, Pacific Chorus Frogs have been verified in Juneau (2003), Sitka (2013) and in Wrangell (2014), though no viable populations have been documented. This same species has showed up in Christmas Trees as far north as Anchorage!
This Pacific Chorus Frog was found on a tote at a seafood plant in Wrangell, AK in July of 2014. Photos by Kelly Buness.
Bullfrogs are of particular concern in Alaska because they are known to devastate native amphibian populations when they are introduced. These large frogs eat anything and everything that they can fit in their mouths, including other frogs and even their own species! They are aggressive, they do well in a variety of climates and habitats, and they frequently carry diseases like chytrid fungus and ranavirus. The federal government foolishly planned to introduce the species in Alaska to "combat mosquitoes" in 1929, but more recently bullfrog tadpoles have been showing up unexpectedly with fish shipments to pet stores.
This Bullfrog arrived in Alaska as a tadpole with a shipment of fish to a pet store. It is now in AHS' possession and is being used as an educational aid. This frog was joined by three additional pet store bullfrogs and proceeded to cannibalize each of them - one reason that we dont want this predator in Alaska!
In the spring of 2013, a resident of Chugiak, Alaska contacted AHS regarding an unknown species of salamander that she found under a flower pot near her house (pictured below). This salamander turned out to be a Blue-spotted Salamander. Upon further investigation, it turned out that the neighbor had intentionally released six individuals of the species the previous fall in order to allow them to "become established in Alaska." They were collected in northern Wisconsin and flown to the state. As was evidenced by the specimen in the spring, at least once individual successfully overwintered.
Photo By Misti Wright
For many years it was thought that reptile releases in Alaska would be less likely to result in the establishment of viable populations because the life history of these species often requires warmer dryer climates than we have in the North. While there is no evidence that viable reptile populations have been established, the possibility of this happening seems to be increasing over time as animals are being observed having successfully overwintered in the state. Even if a released animal eventually dies without producing offspring, it is competing for resources with native species and it can still transmit disease!
Both snakes and freshwater turtles have been observed frequently in Alaska, though no viable populations have been established or confirmed. It is indeed possible that garter snakes occur naturally in Southeast Alaska, especially along three river corridors that provide access from the drier warmer interior where they are actually known to be present, including the Stikine, Taku, and Unuk River watersheds. Credible naturalists reported snakes in these areas in the 1970s, but no evidence of their existence has been formally collected (i.e. live or dead snakes, skins, photographs). AHS and its members have been looking for snakes on the Stikine annually since 2010, and to date none have been found. One likely scenario is that upstream flooding events have occasionally pushed these animals into Alaska but in very low numbers that have not over-wintered successfully, or that have not had the opportunity to breed.
In 2005 a dead garter snake was found on the road in Haines, Alaska. This specimen was studied closely and now resides in the museum at the University of Alaska Fairbanks. Genetic testing suggested that this animal was of a garter snake subspecies occurring naturally far from Alaska. Given this evidence and its distance from any other known snake population, it is assumed that the animal was either a pet, or that it arrived in Alaska with cargo.
This dead snake was found dead on the road in Haines on 8-21-05. It is now in the University of Alaska Museum Collection as catalog number UAM_HERP_31.
Since 2005 reports of garter snakes have been turning up all around Alaska. So far we have had reports from Soldotna, Kenai, Kasilof, Turnagain Arm, Petersburg and Kupreanof. Some of these reports have included photographic evidence!
Freshwater turtles, especially Red-eared Sliders, have been turning up left and right in Southcentral Alaska in recent years. In 2013 alone they were reported in Goose Lake, Sand Lake, and Jewel Lake in the Municipality of Anchorage. The Goose Lake specimen was found by a group of students in the early spring. They initially thought it was dead given its inactivity and its position lodged within an embankment next to the water. After pulling it from the mud, the students soon learned that it was alive. For this reason we believe that the turtle successfully overwintered at that site. Another Red-eared Slider was reported from Cuddy Family Memorial Park in Anchorage in June of 2014, but this animal was captured and is now in captivity.
Red-eared Sliders are far less likely to "escape" an aquarium than a snake or a lizard. These are relatively slow-moving animals with little ability to climb walls. Pet freshwater turtles are notoriously released when they grow too large for their aquariums or individuals no longer want to care for them. They require quite a bit of work to keep their tanks clean. Fish tanks generally have quite a bit of debris on the bottom even though the water "looks" clean due to the filter. Turtles frequently stir-up the otherwise sunken dirt, causing the aquariums to constantly appear dirty. For this reason turtles can be A LOT of work and this should be considered before anyone brings them home as a pet!
In 2002 a snapping turtle was found in a pond near Homer, thousands of miles from its natural range. It was originally described as an "Alligator Snapping Turtle" but AHS believes that this was probably a "Common Snapping Turtle." The general public often interchanges these names and many people do not know they are different. Alligator Snapping Turtles are considered threatened throughout much of their native range, they are more difficult to find as they do not migrate terrestrially, and they have unique life histories. Common Snapping Turtles are far more common and have been introduced around the world. Either way, these species can be aggressive predators, consuming everything frog frogs to fish to ducks. And this wasnt the only snapper found in Alaska! Another was found near Juneau in May of 2011...
This snapping turtle was found near Juneau in May of 2011. Photo by Michael Penn / Juneau Empire.
Perhaps the craziest reptile find to date was an American Alligator in a ditch in Chugiak, AK in the summer of 2013. According to one of our members, Leah Dortch, a report of an alligator reached her Eagle River pet store last year:
"That same year my coworker, Linda, took a peculiar call. The person on the other end wished to know if anyone had called asking after a missing alligator. 'No, we hadn't received such a call'. It seemed that the caller was driving down the road in Chugiak, when they noticed the roughly five foot animal in a ditch. The next question for us was can we take the animal from them? 'We are just not equipped to care for this kind of animal' we recommended the Humane Society, or Anchorage Animal Control and asked them to call back and let us know what happened. Then, we began calling our landlords to see about holding the alligator at our homes over night. For both of us, the reply was a resounding "NO". Meanwhile the caller began knocking on doors in the immediate vicinity. The owner was near at hand and not aware the "little guy" had gotten loose, and was very grateful to have him safely home. So, I did not get to keep the bullfrogs or alligator, but maybe that's okay."