Once the autumn leaves have began to fall, most natural history has gone about their business and well on their way out for the year. In Central Illinois, several orchids, fungi, and a salamander species make exceptions to this guideline. One particular autumn highlight is the elusive Marbled Salamander. They are interesting because reproduction strategies they exhibit are backwards compared to other mole salamanders within their genus, Ambystoma. In early autumn, adults travel to dry vernal breeding pools. Females lay eggs in nests constructed under logs and leaf litter of these dry vernal pool basins. Males soon vacate, leaving females to guard their clutch until fall rains inundate them. This allows overwintered aquatic larvae to attain a voracious developmental head start, being able to feed on other Ambystoma hatchlings come spring. Marbled Salamanders are sexually dimorphic. Males have bright white banding and a noticeably swollen vent at the base of the tail during breeding season. Females have a more grayish banding.
Within Vermilion County, Marbled Salamanders have a tiny population and are rarely seen outside breeding season, if at all. It took me two years to find my first. I spent weekend after weekend crawling around, rolling everything in sight at vernal areas I had mapped while orchid hunting. Since it was a three hour round trip drive to Vermilion County for me at the time, I camped to make best use of my weekends. I lived on hobohash and became quite good at making it by end of year two. I even invested in a folding grate to keep them from charring. Steak, hamburgers, and ears of corn suddenly become viable additions with this Coleman luxury 🙂
I consulted several herp folk regarding how, when, and what to look for in my fall salamander journey. The responses were more or less frustrating than helpful – “they are easy…under stuff, anytime in fall.” This may work where Marbled Salamanders are weeds, as they normally are. But, within a tiny population at the margins of their range, they are specific as hell, as I’ve learned.
Usually, I either find absolutely nothing, numerous males, or one female on a nest.
When lows dip into the 40’s, start looking. Males come out first, signaled by the crash of evening lows, usually in September. Females on eggs can then be found after the next substantial rain. Males appear to vacate, once it rains after this crash in nighttime temperatures. Sometimes the evening temperature drop and rain follow each other. In 2014, there were only 3 days between the two events. Those three days were the entire window for the year to find a male. When males are found, look in other vernal areas. I’ve read some populations have gender ratios as steep as 9 males to 1 female. I feel this is most likely true. The chances of discovering new populations once females nest are pretty slim.
In a different geographic region, your Marbled Salamander experience will most likely be entirely different. This is what I’ve learned from my journey.
This creature is fascinating.
I’d love to hear your story.