C. M. Snyder. Terrestrial salamanders in the Adirondack Mountains: Feeding ecology and implications of calcium. 96 pages, 18 Tables, 14 figures, 2011
Acidic deposition and calcium deficiency may have important impacts on terrestrial salamander prey, feeding strategies, and food web interactions. Litter invertebrates and salamanders connect above- and below-ground ecological processes through predator-prey interactions. Because these organisms are sensitive to environmental changes, they may be influenced by the effects of acidic deposition and used to assess implications of calcium loss in forests. My objectives were to investigate relationships between prey availability, salamander diet selection, and forest floor faunal composition across a twelve site gradient representing calcium variability in northern hardwood forests of the Adirondack Mountains, NY. In June 2010, leaf litter invertebrates were sampled using Berlese funnels. I sampled terrestrial salamanders and their stomach contents were sampled by area-contrained timed searches and gastric lavaging.
The most frequent prey groups found in the stomach contents of 123 red-backed (Plethodon cinereus) and 49 dusky (Desmognathus spp.) salamanders were oribatid mites, non-oribatid mites, springtails, gastropods, and adult flies. Although salamanders shared nearly 68 % of their diet, both species consumed a diversity of prey types, sizes, and quantities. Salamanders appeared to consume prey relatively proportional to their availability in the leaf litter according to my use-availability analysis, confirming generalist strategies common to red-backed and duskies. Red-backed salamanders ate a significantly greater number of calcium-rich prey items including oribatid mites and snails than duskies. Salamander assemblages shifted significantly with increasing calcium availability from dusky dominated (low calcium) to red-backed dominated (high calcium). Multiple regression indicated that the effect of soil calcium and prey availability on the abundance of calcium-rich prey in salamander diet varied by prey group. Oribatid mite abundances in the diet and leaf litter decreased with increasing calcium, while snails in diet were unaffected by increasing soil calcium and snail availability. As a result, diet may contribute Because the Adirondacks have been subject to further acidification and calcium loss, and both snails and oribatid mites were found to be important components of diet, additional investigation is needed to assess the effects of reduced calcium availability on woodland salamander salamanders.