Updated: Dec 2, 2022
A 1.5" newt trying to cross Alma Bridge Rd. Luckily we found it and moved it safely to the hill side
The first 3 months of the 2022-2023 newt season look very different than what we've seen so far, since we started our regular survey back in 2018. First, the short rain event in the middle of September got a small number of adult newts to the road. Very few newts were documented in October, but in early November we started seeing tiny juveniles dead (and sometime alive) on the road. It became a huge wave of 1.5" newts, migrating from the reservoir to the hills in the middle of November. Within just a few weeks, we documented 1,028 juvenile newts, 65% of all juveniles documented on our study.
We should note that juvenile carcasses don't stay on the road for long. One study found that 80% of the smaller bodied amphibian carcasses were gone from the road within 24 hours (Santos et al., 2011; Zhang et al., 2018).
We are not entirely sure why we're seeing this large juvenile migration right now, and what would be the impact on the entire newt population, as juvenile newts deaths have a high impact on population viability (Petrovan et. al., 2019, p 254). We are hopeful, however, that in a few years, when the surviving juveniles mature and head back to the reservoir to reproduce, they will be able to use the newt crossing structures that we are planning for them!
All our newt data in one figure: numbers of dead newts on the road per month
These are the juvenile numbers we had until this season - dead juvenile newts on ABR
Dead juvenile numbers, including the current season - November 2022 numbers stand out!
This season in a map: 1,326 dead newts: 298 adults, 1028 juveniles.
And a few more newt photos...