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Herping Alaska's Rainforests

Updated: 5 days ago

 

Positioned less than 600 miles (ca. 966 km) below the Arctic Circle, Southeast Alaska is wet with more than 16 ft (ca. 5 m) of annual precipitation making it one of the wettest places in the United States. Existing near the coast are forests of Western and Mountain Hemlock, Sitka Spruce, and Alaska Yellow Cedar, and the ground is carpeted with spongy, green moss. In soggy areas, large tropical-looking Skunk Cabbages span tracts of muddy land. While visiting Juneau, we extensively explored these forests, not to find Grizzly Bears, Bald Eagles, or other popularly sought-after creatures, but for the region’s lesser-known amphibians—Western Toad (Anaxyrus boreas), Columbia Spotted Frog (Rana luteientris), Wood Frog (Rana sylvaticus), and Rough-skinned Newt (Taricha granulosa).

Most visitors to Juneau are happiest when it doesn’t rain, but if a person is seeking amphibians rain is the best. When we arrived in Juneau the area was experiencing a drought, so to speak. In the sunlight, thousands of post-larval toadlets gathered into piles, concentrating moisture while warming in the sun. This warming behavior is thought to speed up metabolic growth. Upon approach, the tiny toads jumped wildly into the surrounding grass and shrubs. Soaking in shore water adult toads prepped for the coming night's foraging on dry earth.


Road cruising to spot animals was a delight for my kids and although finding toads was interesting spotting porcupines, marmots, Mule Deer, and Black Bears brought the most excitement. On Douglas Island, porcupines were fairly common, gnawing on roadside flowers and grass.


Around Mendenhall Glacier, likely human-introduced Columbia Spotted Frogs have taken up residence. If not for these introduced frogs, it’s unlikely we would have found this species in Alaska, since native populations exist only in remote river channels—Salmon, Taku, Stikine and Unuk rivers—far from Juneau. In addition to frogs, Mendenhall Valley's lakes provide excellent habitat for Beaver with many woody beaver lodges seen.

Although native Rough-skinned Newts are believed to extend north to Shelter Island (near Juneau), mainland populations at Juneau are regarded as introduced. Speaking with residents of Juneau, I was informed of colonies on Douglas Island, at Tee Harbor, and near Eagle River. Additionally, a report from near Peterson Lake exists on iNaturalist. For breeding, Juneau's newts enter ponds (incl. those created by beavers) and roadside ditches from April into June. In August, the dry conditions that Juneau was experiencing made finding newts tough and it wasn’t until our final vacation night that it rained hard enough to find road-crossing newts. Toads were also on the roads enjoying the rain, and unfortunately, many were squashed by casual drivers.


On Douglas Island, a single colony of Wood Frogs is recognized and whether they are native or introduced is unknown. Although Rough-skinned Newts, Columbia Spotted Frogs, and countless toadlets and adult Western Toads were seen, no Wood Frogs were found. Perhaps due to the week’s dry conditions, the frog’s low population numbers in the Juneau area, or another enigmatic factor. Old-growth temperate rainforests are extraordinarily complex and over thousands of years amphibians have evolved to exploit these habitats, even those far north in Alaska.

 



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