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Newly Constructed Tunnels Help California Tiger Salamanders Cross The Road

Northern California tunnels provide bridge from upland habitat to breeding pond.

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A graduate biology student from Sonoma State University in northern California is tracking California tiger salamanders (Ambystoma californiense) as they wend their way through a series of three newly constructed tunnels built under a road that separates their upland habitat with a breeding pond. The tunnels, which were built in October 2011 by Sonoma county's public works department and water agency with funds from a $10 million Caltrans grant for environmental restoration projects, are designed to get the salamanders to the breeding pond without the need for them to cross the road. In previous years, the salamanders, which are listed as vulnerable on the IUCN Red List, had to cross the road to get to the pond, which resulted in a 5 to 25 percent mortality rate.

According to a report in the Sonoma Patch, graduate student Tracy Bain is working with Sonoma State volunteers and undergraduate students to track the animals and divert them to the tunnels. The road has been blocked with fencing in an effort to prevent the animals from crossing, and the fencing creates a pathway that leads them to the tunnels. Bain wants to do sound science and research on the spotted amphibians, with the goal of getting them to use the tunnels. She said so far the animals have been using the tunnels but the final outcome is still inconclusive because not a lot of salamanders have come out yet due to the lack of rainfall. The final barometer of the success of the tunnels could be the counting of the larvae in the breeding pool across the road.


The California tiger salamander lives in grassland habitat as well as valley-foothill and hardwood areas. It can be found in the northern California counties of Petaluma, Sonoma, the Central Valley, Yolo, Sacramento, Tulare, the San Francisco bay area, and Santa Barbara counties. It feeds on earthworms, snails, insects, small fish and even small mammals such as mice.

You can view a simulated graphic of the tunnel in the Youtube video below.