Diario del proyecto Pacific Newt Roadkill (Main Project)- Lexington Reservoir

It's a difficult and very time-consuming chore to try to eliminate duplicate observations of newt roadkill, especially when there are multiple observers covering the same study area.

Since there can be hundreds and hundreds of carcasses on the road at the same time and it's hard to tell them apart when they start decomposing, one or more methods are necessary for identifying carcasses that have already been recorded in iNat. I really struggled with this issue last year.

Remove Carcasses from the Road? Or not.

In 2017, I was told by one local agency that it's illegal in CA to remove dead animals from the road. This year I was told by a rep from CA Fish & Wildlife that it's ok to remove the dead newts from the road. Because of this contradictory info, I'm confused about whether it's legal or not. See this article for more info:
https://www.google.com/amp/s/www.latimes.com/california/story/2019-12-30/despite-new-california-law-illegal-to-collect-roadkill%3f_amp=true

Often, it's too dangerous or impractical to remove the carcasses from the road. Alma Bridge Road is a winding mountain road that is seeing more and more traffic over the years. It's dangerous enough going out on the road to take pictures of roadkill, especially when it's dark and stormy. The extra time it takes to remove a carcass just adds to the danger.

Observing How Newts Decompose to Determine Age

What I've noticed about decomposing newts:

1. The bright orange/yellow belly color seems to fade to grayish-white within 2-3 days.
2. The bright red blood is gone within 2 days.
3. If carcasses were desiccated before the rain, they absorb water and actually make the carcass look fresher.
4. When it has been raining for days and the road is wet, most of the carcasses decompose into a slimy whitish gray mass within a few days that is almost unrecognizable as a newt. This is very fast decomposition compared to what I saw when there was no rain for a week or more.

Factors that affect how fast an animal such as the newt decomposes are as follows:

• moisture: the amount of water in the environment (rain and fog condensation); organic matter decomposes faster when wet
• temperature: organic matter breaks down faster in warm weather
• integrity: how many times was the newt run over? In areas with a lot of traffic, the carcasses decompose faster.

Separating Observations of Fresh vs Decomposed Roadkill

Last year I took extreme measures to ensure that I did not double-count the corpses because I didn’t want anyone to question my numbers. When I uploaded the pictures to my computer, I sorted out the “fresh” from the “decomposed” corpses. I then compared the decomposed ones with the observations from previous weeks. If there were duplicates, I didn’t upload them to the main project, but rather added them to a project called “Decomp Study” (https://www.inaturalist.org/projects/pacific-newts-decomp-study-lexington-reservoir-area) so that I could understand how the newts decompose and what features to look for. This was an extremely time-consuming process that took hundreds of hours, and in the end, I don’t think it was worth the time and effort. Out of 2,148 decomposed newt pictures, I only found 332 duplicates (15%).

I started taking photos with the newts oriented in the same direction (head to the left, tail to the right) to facilitate comparisons.

Other Methods to Try

• At one point I tried leaving a drop of purple nail polish next to some carcasses. The nail polish dots lasted a couple of weeks. Some, however, disappeared within one week.
• You might try circling the carcasses with sidewalk chalk. This will work best during dry periods, because rain washes away the chalk marks.
• If the GPS coordinates are accurate, you might be able to export a couple weeks of project data to an Excel spreadsheet and sort on the GPS coordinates to find duplicates. I never tried this, but it might be more efficient than comparing pictures. However, when collecting data for the Decomp Study, I found that the corpses often moved from their original location (due to cars, foot traffic, rain drainage, wind?). Some corpses were even flipped over or oriented in the opposite direction over time.

Does it Matter?
There are many reasons to believe that we are undercounting the newt roadkill at Lexington. See the following post:
https://www.inaturalist.org/projects/pacific-newts-all-lexington-reservoir-area/journal/23364-reasons-why-pacific-newt-roadkill-may-be-significantly-under-reported

One could say that the duplicates offset the undercount, so it all evens out.

The best approach would be to survey the road every day and remove any corpses found. However, I don't know anyone who would be willing to do this for the 5 month migration season, especially if the powers that be are not willing or able to staunch the slaughter. Doing this kind of work takes its toll on your psyche and soul.