How do tip-up mounds influence relative salamander abundance?

Tori Engler

Masters Student at Virginia Tech

November 2022

Plethodontid salamanders are small, terrestrial salamanders that roam mesic forests, hiding under leaf litter, logs, and even in holes underground. They are highly reliant on moisture and retreat under cover objects or underground when conditions become too dry (Feder 1983). Interestingly, my previous research in Michigan suggests that in some cases, salamanders have higher relative abundance in areas with artificial tip-up mounds (uprooted and exposed tree root masses). This could be because the pit of the tip-up mound has higher soil moisture than surrounding areas (Clinton and Baker 2000), but it remains largely a mystery. This forms the basis of my thesis research, to determine whether tip-up mounds can promote higher salamander abundance and why that may be.

Figure 1. Coverboard array for salamander sampling with nine boards spaced 1.5 meters apart – Tori Engler

This summer, I put out 3 by 3 coverboard arrays and set up 2 by 15-meter visual transects in 12 treatment units (Figure 1). We allowed the boards to weather in place for about six weeks and began sampling for salamanders by looking under each board once per week in September. On warm rainy nights we did visual transect surveys to look for salamanders to supplement the coverboard sampling. Upon catching a salamander, we measured the snout-to-vent length, tail length, tail width, mass, sex, gravidity and gave the salamander a unique visible implant elastomer dye mark to identify individuals (Figures 2 and 3). 

Figure 2. Tori Engler marking a salamander with implant elastomer dye – George Wenn
Figure 3. Salamander marked with red visible implant elastomer dye under UV light – Tori Engler

Measuring salamanders can be very challenging since they move surprisingly fast. Sometimes the animals are uncooperative and try to escape…by crawling into the scale (Figure 4). Thankfully, after some trial and error, we were able to take apart the scale and safely remove the salamander, without any harm to it. 

Figure 4. Salamander inside field scale – Tori Engler

After we took all the salamander body measurements (and wrangled potential escapees), we measured the distance from the salamander capture location to the nearest natural tip-up mound. This December, I will be using a bulldozer to push over trees in 6 of the 12 treatment units to create artificial tip-up mounds to better understand how tip-up mounds could be impacting salamander abundance. We are currently wrapping up pre-treatment data collection to ensure that any site differences that could impact salamander abundance before treatment implementation are taken into consideration.

So far, we have captured a total of 44 individuals between all treatment units (Table 1). Most captures have been Eastern Red-backed Salamanders (Plethodon cinereus), but we did find one Red Salamander (Pseudotriton ruber). Interestingly, we have found several P. cinereus that are an uncommon silver morph. I am very excited to see how artificial tip-up mounds may influence relative salamander abundance after implementing the tip-up mounds this December.

After I obtain my MS degree, I would like to stay at Virginia Tech to pursue a PhD, expanding on the current project. I hope to discern if tip-up mounds could impact salamander survival, body condition, and even reproduction. Researching salamanders is my passion, and I think this project has the potential to give us important insights into how forest structures like tip-up mounds can impact salamanders.

Literature Cited

Clinton, B. D., and C. R. Baker. 2000. Catastrophic windthrow in the southern Appalachians: Characteristics of pits and mounds and initial vegetation responses. Forest Ecology and Management 126:51–60.

Feder, M. E. 1983. Integrating the ecology and physiology of plethodontid salamanders. Herpetologica 39:291–310.