Going Deep

Spotted Salamander

With the Chill of Fall Salamanders Travel Deep Underground

In the spring Spotted and Jefferson’s salamanders crawl to vernal pools — temporary woodland ponds that fill with water but then dry out later in the summer, providing a fishless environment for larval salamanders, where they mate and lay eggs. But for 90% of the year, these salamanders are elsewhere in the forest. Sometimes you can find them by flipping over a large stone or rolling a rotting log, but for the most part, they are tough to find.

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Technology allowed VCE biologist Steve Faccio to easily spy on salamanders using miniature tags that emit a radio signal. With a radio receiver and small antenna, Steve could then monitor each tagged salamander’s movements and locations.

Standing on a forest path near the site, Steve turned on his radio receiver and tuned to a salamander’s frequency. A faint, but audible “ping” sounded from the headphones. A few minutes later Steve had honed in to the general area of the animal. The signal was strong, but he couldn’t quite pinpoint it. The salamander was underground.

After an hour on hands and knees, Steve found the exact spot. A series of narrow, branching tunnels under the leaf litter and rotting logs held the prize. Steve was able to move just a few leaves and there it was peering out from a tunnel opening.

These salamanders can’t dig. They use shrew, mice and chipmunk tunnels for refuge. In fact, the tunnels are so important to them that Steve could predict areas in the forest that would be used by the salamanders just by the density of mammal tunnels. Without small mammals, there were no salamanders to be found.

After tracking them to these surface tunnels all summer long, suddenly, with the chill of fall, the salamanders changed behavior. They entered more vertical tunnels that led deeper underground. By November nearly all of them were deep under the earth. The radio signal only traveled about two or three feet, so eventually the signals were lost. They had gone deep enough to escape the ground-penetrating frost, and radio spying by biologists from above.

#pdv #pdn

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