Salamanders are known to be exceptional indicators of ecosystem health because they breathe through their skin making them susceptible to changes in water or air quality. A long-term project was started on SEFI in 2006 to monitor abundance and population trends of the endemic arboreal salamanders. Over 100 cover boards were placed at survey sites that are routinely monitored.
|We can identify individual salamanders by their spots.|
During surveys, the salamanders’ body and tail lengths are measured. They are weighed, sexed, and photographed to help in identification. The salamanders have uniquely patterned spots, similar to the personal attributes of our own fingerprints.
Arboreal salamander species occur across the greater California area (from Humboldt County to Baja Mexico) and some have been found on the state’s offshore islets. The Farallon Island salamanders are considered a subspecies due to their different spot patterns. They are called “arboreal,” or living in trees, because of their adapted propensity to climb with enlarged toe tips and a prehensile tail. They tend to be nocturnal and forage for small invertebrates on the ground, under objects, or in rock crevices.
|Photo: Kerry Froud|
After a mostly dry winter, the majority of the bi-monthly surveys on SEFI have found low numbers of salamanders. We were beginning to worry that the ‘manders’ had vacated the island; with survey numbers dwindling to a low of 8. The arboreal salamander is known to be more tolerant of dry conditions than most other salamanders, but it was evident that they were much happier after 2 inches of rain fell at the end of January. February’s first survey equated to a surprising jump to 71 salamanders. At times, there were so many to process that more hands were needed to catch the wiggling critters. Eleven of those caught were immatures, affectionately called mini-manders, and 10 others were adult females with eggs (one even had 6 eggs!) which indicates that Southeast Farallon Island still has a healthy population.
We are currently brainstorming on ideas to expand our sampling area and feeling out other potential data points to collect during these surveys. We hope to gain a better understanding of salamander distribution and if it may be related to the abundance of sub-habitat types and prey abundance. These salamanders have given us yet another unique species to study here on the Farallones and we look forward to where this project might lead in the future.