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 here:

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 100 ft. sections of road (0.1 mile) for their study. Please be aware that our team has found newt roadkill along all 4.1 miles of our study area.

The HT Harvey team started field work building their pitfall traps the week of 10-14-20. Merav spoke with Jeff Wilkinson to coordinate the efforts between his team and ours.

פורסם על-ידי truthseqr truthseqr, אוקטובר 18, 2020 09:47 לפנה"צ



@merav, @sea_kangaroo, @newtpatrol, @joescience1, @anudibranchmom, @biohexx1, @tyap, @karangattu
If you haven't joined the new project for the upcoming migration season, please do so. Also, please join the umbrella project so you can have easy access to all the subprojects.

Regarding the population analysis performed by J. Wilkinson (HT Harvey & Associates, Aug. 2, 2019) using the modeling software by Gibbs and Shriver (2005), my memory fails me so I looked up the exact numbers. These are all estimates (J. Wilkinson gave a long discussion of why he chose these numbers):

Starting population = 15,000 (arbitrary number, ~3.7 times the number of newts killed during the 2018-2019 breeding season)
Carrying capacity of the reservoir as the larval habitat of 2,000,000
Starting adult annual survival rate of 0.9, without mortality from vehicular strikes due to predation, disease, etc.

The report stated: "We do not know whether the observed road mortality on Alma Bridge Road is sufficient to pose a significant risk to the viability of the local newt population..."

"As an exercise, if we were to assume the 45,665 adult population size prior to construction and use of the road, and use the 4,042 number that was tallied this year by Anne to reduce the survival rate due to road mortality to 0.811, the adult population size would plateau at 31,580 after 63 years. This seems plausible because the reservoir and road have been in use for 67 years, yet road mortality of this magnitude is still being observed. If this mortality were to cause a substantial reduction in, or even the extirpation of, this Lexington Reservoir population, the loss of this one population would have a minimal effect on region-wide populations, as this species is common throughout the hills and mountains of the Bay Area."

פורסם על-ידי truthseqr לפני 5 ימים (סמן)

i guess the same mentality could be used with our current pandemic.... ugh.

thanks for posting this anne

פורסם על-ידי joescience1 לפני 5 ימים (סמן)

That mentality is also what leads to extinctions. We decimate the populations little by little, and each little bit doesn't seem like it matters, until it does, and either they're gone or on the endangered species list and now we have to put so much more time, effort and resources into bringing them back than we would have to keep them thriving in the first place. This way of thinking needs to change if we're going to regain balance with the rest of the planet.

פורסם על-ידי newtpatrol לפני 5 ימים (סמן)

Newtpatrol, you are correct. You can see urban sprawl and its consequential increase in traffic. Pollution takes effect as well. Newtpatrol also mentioned population density the other day.

There was a time when zero newts were killed by traffic, then maybe 100 per year, then 500 per year, then a thousand per year, til the number we're at today. The number of roadkill deaths will increase with an increase in usage of the reservoir.

פורסם על-ידי biohexx1 לפני 4 ימים (סמן)

@biohexx1, what you said makes so much logical sense to me. Why didn't J Wilkinson take that into account in his first population modeling? He just assumed 5000 newts were being killed from Day 1 after the road was built. It seems such analyses would be more robust with feedback like this from the team. That first analysis was flawed. Hopefully he will take all this into account with his second analysis after collecting data this year. Hopefully @merav will be able to review his report before it's released to the "partners" this time.

פורסם על-ידי truthseqr לפני 2 ימים (סמן)

That's why we meet and strategize! Together we will come up with a good mitigation plan.

פורסם על-ידי biohexx1 לפני 2 ימים (סמן)

I'm going to speak today at Supervisor Ellenberg's meeting at noon (district 4). I would like to ask her why they are repaving the road without doing anything for the newts. They still have half of the road to repave, so maybe it's not too late? I'm guessing it is too late, but I'd like to at least say something about it. When I was there yesterday I thought it was crazy they are doing nothing for the newts. I'm sure the most expensive part in adding an underpass for newts is repaving the road. Since they are already doing that, they could have added pipes or something, or fix a few culverts.

פורסם על-ידי merav לפני 2 ימים (סמן)

Wow! Thanks so much, @merav!
When I started this project, I didn't know who to report it to or who had the power to do something about it. Linking up with you and Shani @ Audubon was the best thing for the newts. You two know all the players and how to get things accomplished. Thanks a million!

פורסם על-ידי truthseqr לפני 2 ימים (סמן)

I have no idea either. It was Shani's idea :)

פורסם על-ידי merav לפני 2 ימים (סמן)

What did the Supervisor say, @merav?

פורסם על-ידי truthseqr לפני יום אחד (סמן)

I was the last one to speak, so she didn't get a chance to reply. But Harry Freitas from County Roads was there, and he said how he feels sorry for the newts, and how complicated it is to implement a solution to this problem, and that he's working with the population study and provides funding for something. So, he didn't say much, but I think it's good that the supervisor is now aware of the problem, Shani hasn't communicated with her before about this. I might ask for a personal meeting with her.

פורסם על-ידי merav לפני בערך 22 שעות (סמן)

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