Case Study #2: 64% of dead newts "disappeared" from the road in 4 days
This is an interesting case:
- @sea-kangaroo surveyed the southern half of Alma Bridge Rd. on 1/14/2020 and found 129 dead newts.
- @newtpatrol surveyed the same section of road on 1/18/2020 and found 65 dead newts; 19 of these were fresh, 46 were decomposed
So, one would suppose there would be 129 decomposed newts on the road on 1/18, since there were that many newts reported on 1/14. However, only 46 decomposed newts were found. That means 83 dead newts "disappeared" in the four days between 1/14 and 1/18 (64%). Where did they go?
FYI: @merav, @joescience1, @anudibranchmom
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Ideas without knowing much:
Wheels of increased weekend traffic? They are pretty delicate.
or
Foxes/skunks/opossums/raccoons/corvids etc? (I've seen a lot of scat along the road)
these are all good options, but I think we also need to keep in mind differences between us - some people might notice more than others. I often see one of the decomposing newts on the road, and think how easy it would have been to miss it. I look back, to check if I missed others, knowing that I might have. In addition, weather conditions affect our ability to document - when it rains/ the road is very wet - I'm sure I miss more decomposing newts, as they are the exact color of the wet road.
Considering all that, I feel better about the newts that we count twice - though it might happen, there are many more that we miss.
All very good points. Thanks for brainstorming this scenario.
I think it's questionable whether scavengers cause the total "disappearance" of roadkill newts. From what I've seen, the scavengers eat part of the newt in situ rather than carry it away.
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
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