Lexington Newt Population Study (2020-2021)
A Pacific Newt population study will be conducted by HT Harvey & Associates in collaboration with Peninsula Open Space Trust (POST) and Midpeninsula Regional Open Space District (MROSD) for the migration season starting late November 2020 and ending sometime between April and May 2021. Daily field operations will be led by a biologist from one of the above agencies paired with volunteers.
The study protocol is considered proprietary (POST asked @merav to review it, but no one else on our team has seen it). However, you can read their public-facing Request for Funding memo (including a map of the study area marking the 6 arrays).
The study objectives are as follows:
"The planned newt population and mortality study will estimate the number of adult newts attempting to cross Alma Bridge Road to breed in Lexington Reservoir and the percentage that are killed by vehicular strikes during a single breeding season. The data will be analyzed through a model to characterize this percentage relative to long-term impacts on the local newt population... The report will also provide daily levels of vehicular traffic and how these levels compare with levels of newt movement. "
The study was prompted by Santa Clara County Roads, Parks, & Water departments who stated that "further study is needed to better understand the issues..."
The HT Harvey analysis of our 2018-2019 roadkill data found "a concentration of mortality along a few road segments" which they deem "Extremely High Mortality." See the map attachment in the above memo. They will install pitfall traps along six 200 ft. sections of road (0.2 mile) for their study. Please be aware that our team has found newt roadkill along all 4.1 miles of our study area. In December, the study team decided to extend the perimeter of their study sites by 50 ft. on each side of the six pitfall traps.
The HT Harvey team started field work building their pitfall traps the week of 10-14-20. Merav spoke with the HTH lead to coordinate the efforts between his team and ours. They committed to share photos of all dead newts found within their study boundaries so that we can compare data with previous years.
References:
Midpeninsula Open Space District website about their newt population study:
https://www.openspace.org/visit-a-preserve/plants-wildlife/newts
Also see the many comments under the original posting of this info:
https://www.inaturalist.org/posts/43032-lexington-newt-population-study-2020-2021
Comments
׳I wonder about this - "The report will also provide daily levels of vehicular traffic and how these levels compare with levels of newt movement. "
I only saw the traffic study being done once. It could have been there for one day or possibly up to 2 weeks or so, but they are not getting daily data.
I think they started checking the traps around 11/2.
@merav, @tyap, I certainly hope they share their final report with you before it's released to the "partners". It will be interesting to see how they explain the very brief traffic study, the expansion of their 6 study areas by 50ft. on both sides, and other deviations from their initial study proposal.
Note: Since the traffic monitoring equipment was removed before the January surge in traffic prompted by Los Gatos Rowing Club lessons in January 2021, the Population Study's traffic data will not be very accurate.
@merav,@newtpatrol, @joescience1, @sea-kangaroo, @anudibranchmom, @karangattu, @tyap:
POST assured Merav that the traffic monitoring equipment for the population study has NOT been removed. It turns out the traffic monitoring equipment our team noticed was installed by County Roads for other purposes and later removed.
I've re-read the Request for Funding memo again, and I'm wondering why they specifically refer to adult newts over and over again. Are they specifically excluding juveniles from their study? I've read that some population models do not take juveniles into account. However, it doesn't appear that they're measuring the newts to determine which are juveniles vs. adults. I hope HTH is using a population model that takes juveniles into account, otherwise it will call into question the accuracy of their predictive results.
Please see the following project for info on how juvenile deaths disproportionately affect population viability:
https://www.inaturalist.org/projects/pacific-newts-dead-juveniles-lexington-reservoir
that's a good question about the juveniles. I don’t know
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