Northeastern Naturalist 648 R.T. Meyer, A. Weir, and T.R. Horton 22001155 NORTHEASTERN NATURALIST 2V2(o3l). :2624,8 N–6o5. 13 Small-Mammal Consumption of Hypogeous Fungi in the Central Adirondacks of New York Robert T. Meyer1,*, Alexander Weir1, and Thomas R. Horton1 Abstract - Small mammals are generally known to consume and disperse subterranean (hypogeous) fungi, but accounts for this behavior are lacking for the northeastern US. We report on the use of these fungi by a sample of small mammals from the central Adirondack Mountains of New York. We analyzed 57 fecal samples from Peromyscus maniculatus (Deer Mouse), Myodes gapperi (Southern Red-backed Vole), Tamias striatus (Eastern Chipmunk), and Blarina brevicauda (Short-tailed Shrew) to determine whether they were consuming fungi in the central Adirondack Mountains. We found that fecal samples from Eastern Chipmunk (n = 12), Southern Red-backed Vole (n = 14), Short-tailed Shrew (n = 14), and Deer Mouse (n = 17) contained Glomus spp. (arbuscular mycorrhizal fungi) spores (33.3%, 35.7%, 21.4%, and 17.6% of samples, respectively) and Russulaceae spores (66.6%, 35.7%, 7.14% and 5.9% of samples, respectively). One sample from an Eastern Chipmunk also contained Gautieria spores. Introduction Mycorrhizal fungi create connections between trees and facilitate increased water- and mineral-uptake into tree roots (Smith and Read 2008). Hypogeous fungi, such as truffles, typically form mycorrhizal associations, and small mammals and invertebrates disperse their spores. There is evidence that certain mammal species are able to detect the odor of underground fungi (Fogel and Trappe 1978). When small mammals eat the fruiting body of the fungus, the spores move through their digestive tract, are defecated, and then sometimes germinate to form mycorrhizal associations in a new location (Ashkannejhad and Horton 2006, Nuñez et al. 2013, Trappe and Maser 1976). Mycophagy, the consumption of fungi, may provide some mammals with essential minerals and carbohydrates while facilitating the dispersal of spores across the landscape (Fogel and Trappe 1978). Many mammals that consume fungi have large home-ranges that span different vegetation types and they can thus inoculate different ecological communities with spores of hypogeous fungi (Ashkannejhad and Horton 2006, Ovaska and Herman 1986). We examined fecal samples from several small mammals captured at a study area in the central Adirondack Mountains of New York to document consumption of hypogeous fungi by small mammals in this region. 1Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210. *Corresponding author - rtmeyer13@gmail.com. Manuscript Editor: Frederick A. Servello Northeastern Naturalist Vol. 22, No. 3 R.T. Meyer, A. Weir, and T.R. Horton 2015 649 Study Site We chose two study sites in the Huntington Wildlife Forest of the SUNY-College of Environmental Science and Forestry, located in the Adirondack State Park in Newcomb, NY. The first site is a natural area that consists of 365 ha of old-growth forest with mixed conifers and deciduous trees. The second study site, called the Hare Area, consists of 60 ha of Picea sp. (spruce)–Abies sp. (fir)-dominated forest. Historical, topographical, and vegetative characteristics of the study area have been previously reported in McNulty et al. (2008). Methods We trapped small mammals and collected feces for analysis of fungi use during 16–19 July 2007, which is the early stage of the annual fruiting period for fungi (July–October). We set up a 7 m x 7 m grid with trap stations spaced 20 m apart in both areas. We used 1 small and 1 large Sherman trap at each trap station (98 traps total). We baited traps with peanut butter, rolled oats, and paraffin (ratio of 1:4:2); the traps were set out in the evening and checked in the morning for small mammals. We marked captured animals by attaching an ear tag if the ear’s pinna were large enough or with Wite-out® if the pinna were too small or absent. We collected feces from the trap floors and placed the samples in labeled envelopes to air dry. We then cleaned the floor of the trap with a damp cloth to remove excess feces and prevent contamination of feces from other captured individuals; marked animals were released on site. Feces of recaptured animals were used unless the animal had been caught the previous night. Once dry, the envelopes containing fecal samples were kept in a jar with Drierite ® anhydrous calcium sulfate. We pre-sampled stored spores in September 2013 to confirm that they were still identifiable after >5 y in storage, then began our analysis. We placed 25 mg from each fecal sample into its own 0.5-dram vial with 1 mL of 15% ethanol to rehydrate the sample (Pyare and Longland 2001). We used a clean mall probe to break apart large pellets and 3 pulses of a Vortex Genie 2 mixer (Fisher Scientific, Bohemia, NY) to homogenize each sample. To create a slide for microscopic analysis, we plunged a pair of smooth-sided tweezers to the bottom of the vial, closed the tips, and withdrew the tweezers, applied the residue to a clean slide, and air-dried the sample for ~2 minutes. To identify the spores, we made 2 covered slides for each sample—1 with 1 drop of Melzer’s reagent to determine staining characteristics and 1 with 1 drop of 100% glycerol to compare to the spores with Melzer’s and preserve the sample. We viewed samples under a Nikon E-800 research microscope equipped with differential interference contrast (DIC) optics starting at 40x, frequently switching to 60x and 100x objectives to give more detail for identification of fecal contents (Pyare and Longland 2001). We classified spores as hypogeous if they were radially symmetrical, a characteristic of hypogeous fungi. We examined each slide for 15 minutes to control effort per slide and identified fungal spores to family or genus using spore keys (Castellano et al.1989, Morton and Benny 1990). Northeastern Naturalist 650 R.T. Meyer, A. Weir, and T.R. Horton 2015 Vol. 22, No. 3 Results We found spores of hypogeous members of Russulaceae, Glomus spp., or Gautieria spp. in 24 of the 57 fecal samples, with 6 samples containing more than 1 species of fungi. Tamias striatus L. (Eastern Chipmunk, n = 12), Myodes gapperi (Vigors) (Southern Red-backed Vole, n = 14), Blarina brevicauda (Say) (Short-tailed Shrew, n = 14), and Peromyscus maniculatus (Wagner) (Deer Mouse, n = 17) fecal samples contained Glomus spores in 33.3%, 35.7%, 21.4% and 17.6% of samples, respectively, and Russulaceae spores in 66.6%, 35.7%, 7.14% and 5.9% of samples, respectively. One sample from an Eastern Chipmunk contained both species of fungi as well as Gautieria spores. We frequently encountered spores of other epigeous fungi in fecal samples but they were ignored for the purposes of this study. Discussion All 4 small-mammal species were clearly consuming hypogeous fungi, both Glomus and Russulaceae species, during the July sampling period, and our results indicate that fungi are a common item in the animals’ diets. If consumption of bait in traps influenced our results, we believe that would have caused us to underestimate the percent occurrence of spores in feces. There were indications of greater use of hypogeous fungi by Eastern Chipmunks and Southern Red-backed Voles than by Short-tailed Shrews or Deer Mice, but we were unable to assess relative use because of the small number of fecal samples and the short sampling period. It is notable that our results from Southern Red-backed Voles are consistent with reported use of Russulaceae fungi across the species’ range (Maser and Maser 1988, Pastor et al. 1996). It is also notable that spores of several hypogeous species were absent in our samples. Much of the literature on small-mammal mycophagy involves the presence of Endogone (Zygomycota) and Hymenogaster (Basidiomycota), and both types of fungi have been reported as being consumed by small mammals in the northeastern US (Hamilton 1941, Whitaker 1962). Our short sampling time and small sample size may explain the absence of Hymenogaster, which has seasonal fruiting habits (Castellano et al. 1989). Endogone spp., however, fruit year-round and are common throughout the northern hemisphere (Trappe et al. 2009). Endogone’s absence in our samples may be an artifact of the taxonomic changes to the group since the 1970s. Some of the spores we identified as Glomus may have been previously considered to be Endogone species. Given our observed use of hypogeous fungi by Short-tailed Shrew, Deer Mouse, Eastern Chipmunks, and Southern Red-backed Voles, these and other small mammals may have important roles in the dispersal of mycorrhizal fungi in northeastern US forests. To better understand that role, future studies should seek to determine the relative consumption and temporal changes of fungal consumption. Northeastern Naturalist Vol. 22, No. 3 R.T. Meyer, A. Weir, and T.R. Horton 2015 651 Acknowledgments We would like to express our gratitude to Andrea Reinheart Perez for the collection of fecal samples. Thank you to Stacy McNulty and Charlotte Demers for their helpful comments on early versions of the manuscript and to the SUNY ESF Adirondack Ecological Center for logistical support. We thank Dr. James Trappe for his contribution to spore identification during the project. Literature Cited Ashkannejhad, S., and T.R. Horton. 2006. 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