Wyoming Wildlife - April 2020

Tigers in Wyoming

Tiger salamander markings in Wyoming vary substantially in color and pattern. (Photo by Zachary Lange)

A man's search for the Cowboy State's lone salamander species proved to be an unforgettable experience

4/17/2020 8:58:08 PM

Starting as stray drops at midnight, the pitter-patter of rainfall steadily increased on my room’s large window that framed the Grand Tetons. Despite the comfort of my bed, I roused myself, throwing aside the covers and planting my feet on the floor. Minutes later, I burst into the summer shower, jogged to my car and drove to Yellowstone National Park in search of a creature which had proven elusive during previous searches.
In the park, I wound up and down mountain slopes. The wiper blades streaked rhythmically across the windshield; the headlights pierced the shroud of fog and illuminated the dark landscape. As I crested a hill and the lights panned the declining road, my eyes widened and my mouth dropped open at the sight before me. The blacktop seemed to be shifting, morphing before my eyes. Squinting, I made out hundreds of moving shapes, crawling across the pavement in the sprinkling mist. Could this be what I was looking for? I pulled over the car and hopped out, flashlight in hand. As I crept toward the moving mass, the light beam revealed moving shapes in combinations of hues: green with black spots, black with yellow blotches, no spots or colors and just a drab lemon and Army green. Creatures ranging from 5 inches to a foot long crossed the road in hoards. Their oversized heads were rounded at the snout, and their eyes permanently bulged. Four distinct toes adorned the front feet, while the back feet had five. They sported prominent grooves on both sides of their bodies and long, hefty tails. Most crawled nimbly to their destinations, while others, weighed down by girth, waddled unhurriedly across the thoroughfare.

Author Benjamin Baker witnessed this tiger salamander and hundreds of others as they migrated to breeding ponds in Yellowstone National Park. (Photo by Benjamin Baker)
Alas, after years of searching for these elusive creatures, I had finally found not one, but hundreds of tiger salamanders. Residing in the eastern United States, for years I drove remote roads during rainy nights looking for tigers. I saw the other salamander species more common in that region, but had never seen a tiger salamander.
More tigers appeared throughout the night. Miles of roads came alive with the journeying amphibians. As I watched, other vehicles driven by early-morning travelers swooshed into the impromptu migration. I cringed at the salamanders’ fate. I did what little I could to wave the vehicles around the creatures, and even moved some tigers across the road myself. Still, many perished.
As I surveyed the scene, I realized these amazing amphibians were trekking from the surrounding woods to a vast clearing with several rain-formed ponds and pools. What exactly is this nocturnal denizen of Yellowstone National Park that I was so fortunate to see? I was witnessing a migration event of tiger salamanders. Their modus operandi was as old as the earth itself: to reproduce.
Resilient and Versatile
Wyoming is home to only one species of salamander, the western tiger salamander (Ambystoma mavortium). Its name derives from the body markings most common to the species: vertical stripes that resemble its feline namesake. As I had seen during their rainy migration, in Wyoming, adults can have a wide variation of coloration.
The tiger salamander has an average lifespan of roughly 10 to 16 years. Born in the water, it begins life gilled and finned only to metamorphose several months to a year later and make its home in forests, deserts, swamps and unforested grasslands.
Although widespread in Wyoming, they are difficult to find because they aren’t often seen above ground. Once on land, tiger salamanders spend their lives underground in burrows, which they often dig themselves. People can walk in a forest unaware a tiger is submerged just under their feet. When they leave their subterranean residences, they feed on whatever they can fit into their wide mouths — insects, worms, snails, zooplankton, minnows, frogs, mice and sometimes other tiger salamanders.
Wyoming’s tiger population has to be hardy and versatile in order to survive in the state’s harsh climate. The tiger salamander population in the state, “appears stable, but localized declines can occur due to disease or changes in water quality,” said Wendy Estes-Zumpf, herpetological coordinator for the Wyoming Game and Fish Department.
These natural and human-caused environmental challenges have compelled tiger salamanders to develop special adaptations and spend winter in some unexpected locations. 
“Terrestrial adults will typically overwinter underground in burrows or other places where they won’t freeze,” Estes-Zumpf said.
These “other places” include prairie dog towns, window wells, manure heaps and beneath logs. In Wyoming, tigers start to emerge in March or April to head to their breeding ponds. The cold-blooded amphibians can travel several miles in the dead of night, in freezing weather and across snow and ice to get to their breeding destinations.
A drive to adapt
It was this emergence of salamanders I witnessed that summer night in Yellowstone. From a clearing abutting the woods, I beheld in fascination the mating ritual of the western tiger salamander: the male nudging the female and vice versa, the sperm of the male contacting her vent and saw larval masses around water grasses in the temporary pools. Some multitasking tigers lunged at worms and grasshoppers.
The larvae deposited into those ponds and other breeding areas across the state possess amazing adaptability. 
"Perhaps the most interesting fact about tiger salamanders is that they are one of only a few amphibians able to postpose metamorphosis into terrestrial adults if conditions are favorable in the pond where they hatched,” Estes-Zumpf said. 
Through an extraordinary evolutionary ability, juveniles can choose to retain gills and become aquatic adults instead of growing lungs, a phenomenon called paedomorphosis. The salamanders can develop lungs and leave the pond later if water conditions become unfavorable,  Estes-Zumpf explained.

Feathery external gills distinguish tiger salamander larva from tadpoles and fish. (Phooto by Chorlotte Snoberger/WGFD)
Lone representative
These unique and resilient qualities are what convinced Wyomingites the tiger salamander deserved a place as the official state amphibian. The tiger salamander’s recognition by the state, though, came from an unlikely place. In early 2019, science students at Pathfinder High School in Lander noted Wyoming did not have a state amphibian. Excitedly, the students researched the dozen or so amphibians in the state. Not surprisingly, they were most impressed by the tiger salamander. The students wanted it to be honored as the state amphibian because “it is a tough, adaptable amphibian that has evolved to handle Wyoming's harsh environment very well,”  Estes-Zumpf said.
The students jump-started the initiative and wrote to Wyoming Gov. Mark Gordon. In the letter, they pointed out the lack of a state amphibian and nominated the blotched salamander, the most common subspecies of western tiger salamander, for “its ability to thrive in Wyoming and its contributions to so many Wyoming ecosystems.” On Feb. 19, 2019, the governor signed a law instating the tiger salamander as Wyoming’s state amphibian, taking its place among the state’s other iconic animals including the American bison, western meadowlark, horned lizard, cutthroat trout, the triceratops and Sheridan’s green hairstreak butterfly.
As the morning light first appeared over Yellowstone that fateful day, the tigers dissipated back into the fog, returning to their subterranean lairs until the rain beckoned them to the surface again. In the subsequent days I toured the park gazing at gushing geysers and perambulating picturesque peaks, but nothing surpassed the midnight migration.
Sometimes, in the small of the night when I am awakened by the patter of rain on my window, I remember that magnificent migration, and I am in awe of the tiger salamander.
Benjamin Baker teaches writing during the day and looks for amphibians at night. This is his first contribution to Wyoming Wildlife.


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