Lessons Learned from a Tiger Salamander Roadkill Mitigation Project

Lessons Learned from Stanford University where they installed California Tiger Salamander (a state and federally listed species) under-crossings on Junipero Serra Boulevard: https://www.sfgate.com/bayarea/article/Tunnel-of-love-for-Stanford-s-salamanders-2883540.php

Here is a synopsis of their feedback:

1) In areas of ongoing mass mortality, it may not be an immediate emergency (i.e. if it is happening year after year, the overall population may be able to sustain the loss). However, it is still heartbreaking.
2) Assisted migration is very dangerous especially on a busy road with vehicles traveling at high speed, especially in wet and dark conditions. Coordinating assisted migration is also difficult. Groups may show up when there are no animals or not be available when animals are present. Any human injury or death resulting from assisted migration efforts (while horrific in itself) would likely result in diverting staff away from other priority conservation issues (such as special status species recovery work, wildfire risk reduction etc.)
3) Discussions were held with the County about closing the road, and while possible, it would only be for a few days a year and not at the last minute. Since it is difficult to predict when animals would be dispersing and/or because animals cross on so many nights a year, road closure was ultimately not considered a reasonable option (i.e. Animals may not cross when the road is closed and/or it would require ongoing road closures).
4) Signage- similar to road closure, signs lose their effectiveness and trying to time signage to when animals cross is difficult. When they did use temporary signs, the signs went missing.
5) Long term undercrossing with directional fencing are difficult to get a design that works (animal needs are different that road maintenance needs) - it takes time. The area at Stanford was so broad (1+mile) that there was the potential for multiple crossings to cause drainage issues. Similar to Highway 17, there can also be conflicts with existing utilities (such as buried gas lines). There is also some worry that lengthy fencing may be counterproductive - if too long and an animal turns around it may not have an alternate breeding location available. Crossings that work can difficult to maintain. Stanford has focused on shifting the salamander population away from the roadway to an area in the foothills (habitat enhancement in areas away from roads).
6) Newspaper publicity if linked to a specific site can be dangerous if people respond to rescue animals. They may pull off to the side of the road to help which can be very dangerous to the rescuer and other drivers.

Newts have it especially tough in this area as the watershed itself has been so modified and the presence on invasive species such as fish and bullfrogs in the lake may eat the ones who do make it across the road. An important question is if the overall population is so robust that it can sustain large mortality numbers (i.e. are hundreds to thousands of newts born in the area each year so there is no net loss?) Wildlife biologists often study this question for protected species, but it would also be worth looking at for species at risk.

Posted by truthseqr truthseqr, February 09, 2019 09:50



This is interesting info - it would be good to have a chance to see the birth rates. Not that it changes the horror of the mass casualties.

Posted by jilliankern 7 months ago (Flag)

@jilliankern, I agree. I contacted Midpeninsula Regional Open Space District's (MROSD) senior wildlife biologist. She said she's contacted all agencies in the area and no one is doing any monitoring of number of eggs laid or young born. MROSD can't do these studies because the county "owns" the water. I asked her if it would be worth petitioning the Santa Clara Water Dept. to do these studies, but she never answered my email.

Posted by truthseqr 7 months ago (Flag)

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