Reasons why Pacific Newt roadkill may be significantly under-reported

I'm reposting this entry from January 15, 2019 (with some additions) to emphasize its importance. As horrifying as the total death count is (5,349 as of 4/13/19), we may be under-reporting the actual number killed on Alma Bridge Rd. Here are the reasons:

(1) The entire length of Alma Bridge Rd. (4.1 miles) may not be able to be covered every survey date. The average coverage per survey date in 2018-2019 was 47%. Therefore, the death toll could be as high as twice what we've reported!

(2) Sometimes newts are injured and are able to crawl off the road before dying. Therefore, they might not be counted as roadkill.
** https://www.inaturalist.org/projects/pacific-newts-roadkill-2020-2021-lexington-reservoir-f5033b15-cd3e-4729-90e6-1cb52825880c/journal/44839-dec-20-2020-north-side
** https://www.inaturalist.org/projects/pacific-newts-injured-lexington-reservoir

(3) Carcasses disappear from the road over time. Here are two examples:
a. Case Study #1: Ten newts found in am, only one left by pm:
https://www.inaturalist.org/projects/pacific-newts-roadkill-2019-2020-lexington-reservoir/journal/30239-case-study-1-ten-newts-found-in-am-only-one-left-by-pm
b. Case Study #2: 64% of dead newts "disappeared" from the road in 4 days:
https://www.inaturalist.org/projects/pacific-newts-roadkill-2019-2020-lexington-reservoir/journal/30234-case-study-2-64-of-dead-newts-disappeared-from-the-road-in-4-days

(4) Carcasses disintegrate beyond recognition when many cars run them over. The traffic throughput on weekends is sometimes as high as 90+ vehicles per hour going to and from the Los Gatos Rowing Club. Imagine what a small, soft-bodied newt looks like after it's been run over by 90+ vehicles.

(5) Dead newts may be carried away on car, truck, or bike tires. Here's a post by @karangattu that show pieces of newts he found on cars parked by the road - https://www.inaturalist.org/projects/pacific-newts-roadkill-2020-2021-lexington-reservoir-f5033b15-cd3e-4729-90e6-1cb52825880c/journal/45347-jan-9-2021-north-side

(6) When there's a lot of rain, the carcasses tend to turn to mush rather quickly and they look like grayish splats on the road. You wouldn't even know they're newt roadkill unless you know what to look for.

(7) And then there are the mud and rock slides. Maintenance trucks may scrape away newts along with the mud and rocks when they clear the roads.

(8) We have not taken into account the effect that scavengers may have on newt roadkill count. According to Greg Pauly, Curator of Herpetology, Natural History Museum of Los Angeles County, "Raccoons, skunks, otters, crows, and ravens are all known predators of newts. While garter snakes swallow newts whole and therefore get exposed to the full dose of toxins (which of course is highly variable across species and populations within species), these bird and mammal predators tend to slit the animals up the belly and then eat the muscle tissue inside, often pulling limbs out. This leaves behind most of the organs and the skin with some or all of the limbs turned inside-out."

• I've seen crows eating the newt carcasses on several occasions:
  https://www.inaturalist.org/observations/19649069
  https://www.inaturalist.org/observations/19649066
  https://www.inaturalist.org/observations/19476078

• I've also seen beetles that appear to be eating newt carcasses:
  https://www.inaturalist.org/observations/19375712
  https://www.inaturalist.org/observations/19354057
  https://www.inaturalist.org/observations/19184311

Posted on April 13, 2019 11:44 AM by truthseqr