SMALL MAMMAL ABUNDANCE ON THE STANDING ROCK AND LAKE TRAVERSE INDIAN RESERVATIONS IN NORTH AND SOUTH DAKOTA

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1 Proceedings of the South Dakota Academy of Science, Vol. 97 (2018) 83 SMALL MAMMAL ABUNDANCE ON THE STANDING ROCK AND LAKE TRAVERSE INDIAN RESERVATIONS IN NORTH AND SOUTH DAKOTA Michael P. Gutzmer 1 *, Kurt Tooley 1, Madeline S. Franks 1, Christopher J. Shank 1, Seth M. Gutzmer 1, Wyatt P. Gutzmer 1, Jeffrey C. Kelly 2, Alvah Quinn 2, and Anthony T. Byrne 2 1 New Century Environmental, LLC Columbus, NE USA 2 Standing Rock Game and Fish Department Fort Yates, ND USA 3 Sisseton Wahpeton Oyate Natural Resource Department Agency Village USA 4 EcoResource Solutions, Inc. Arvada, CO USA *Corresponding author mgutzmer@newcenturyenvironmental.com ABSTRACT Small mammal diversity and abundance were assessed from traps set in various relatively undisturbed habitats on the Lake Traverse Indian Reservation in 2011 and 2012 and on the Standing Rock Indian Reservation in 2014 through The purpose of these efforts is to document diversity and abundance of mammal species and compare catch rates within two slightly different eco-regions in North and South Dakota. Seven species were captured on the Lake Traverse Indian Reservation; the most common were deer mice (Peromyscus maniculatus) and white footed deer mice (Peromyscus leucopus). On the Standing Rock Indian Reservation, we documented nine species of small mammals: deer mice and meadow voles (Microtus pennsylvanicus) were the most common. Two species of Conservation Priority (Level III) were also captured: the hispid pocket mouse (Chaetodipus hispidus) and the plains harvest mouse (Reithrodontomys montanus). Species abundance between years at each site, as well as between both sites, were not significantly different. Catch rates were higher on the Standing Rock Indian Reservation compared to the Lake Traverse Indian Reservation. Keywords Catch rates, Small mammals, Standing Rock Indian Reservation, Lake Traverse Indian Reservation INTRODUCTION The effects of global climate change include increased average annual temperatures and changes in precipitation patterns and are predicted to cause changes in

2 84 Proceedings of the South Dakota Academy of Science, Vol. 97 (2018) the structure and dynamics of ecological communities. For example, many small mammal species are coming out of hibernation and breeding earlier in the year than they did several decades ago, while others are expanding their ranges to higher altitudes (Moritz et al. 2008). In addition, some mammalian species show trends toward larger body sizes, most likely due to increasing food availability and higher temperatures (Millien et al. 2006). As predators and foragers and prey, small mammals are vital links in grassland food webs, and are often indicators of habitat quality (Davidson et al. 2012). Thus, changes in a grassland community may be identified through changes in small mammal abundance or composition. Historic and current land use practices have affected many native species in the Great Plains. For example, bison and other large herbivores have been extirpated since the 1870 s. More recently, large predators and other grassland species have begun to demonstrate widespread declines (Sampson and Knopf 1994). The objectives of our study were to assess the small mammal species diversity and abundance in various habitats on the on the Standing Rock Indian Reservation (SRIR) in north-central South Dakota and on the Lake Traverse Indian Reservation (LTIR) in northeastern South Dakota. The data will be used to establish a baseline for comparison to future studies. METHODS Study Sites. The Standing Rock Indian Reservation consists of approximately 2,300,000 acres in Sioux County, North Dakota, and Corson County, South Dakota (Figure 1). The reservation lies within the Northwestern Great Plains ecoregion; 43a Missouri Plateau, 43c River Breaks, and 43j Moreau Prairie (Chapman et al. 2001). Rolling hills, woodlands, river valleys and lakes dominate the reservation. The Great Plains Region Inter-Tribal Wetlands and Waterfowl Enhancement Initiative estimated that there are 134,000 acres of wetlands within the boundaries and 700,000 acres of associated uplands (Environmental Profile). Approximately 300 km east of the (SRIR), the Lake Traverse Indian Reservation of the Sisseton-Wahpeton Oyate tribe is located in the northeast corner of South Dakota, mostly in Roberts County, but with a portion in adjacent North Dakota (Figure 1). It lies within the ecoregion adjacent to the Northwestern Great Plains, the Northern Glaciated Plains ecoregion; 46c Glacial Lake Basins, 46e Tewaukon Dead Ice Moraine, 46i Drift Plains, 46k Prairie Coteau, 46m Big Sioux Basin, and 46o Minnesota River Prairie (Chapman et al. 2001). The total tribal land area in South Dakota is approximately 125,000 acres. The reservation consists of a mosaic of wetlands and glacial lakes, as well as agricultural lands.

3 Proceedings of the South Dakota Academy of Science, Vol. 97 (2018) 85 Figure 1. Small mammal survey locations: Standing Rock Indian Reservation (Standing Rock Sioux Tribe) and Lake Traverse Indian Reservation (Sisseton Wahpeton Oyate). Sampling Procedure. Snap traps, baited with peanut butter on the trigger mechanism were placed in selected habitats (Table 1). Where possible, two parallel transects of traps were set at 25 stations placed meters apart for a total of 50 traps per transect (Biological Services 1997). In some riparian habitats and woody draws, transects could not be run in parallel lines to accommodate the land form. When obstructions prevented traps from being included along the transect, they were placed approximately one meter perpendicular to it. Table 1. The number of traps placed by habitat on the Standing Rock Reservation and Lake Traverse Reservation. Habitat Description Standing Rock Number of Traps Lake Traverse Wetland Wetland complex/riparian (Shoreline) Grassland Grass/Prairie/Pasture Wooded Woodland/Small Tree/Shrub/Shelterbelt Coulee/Ravine Dry Coulee/Draw/Ditch Agricultural Fields (corn)/field Fence Line Peri-domestic Within/Nearby Human Development

4 86 Proceedings of the South Dakota Academy of Science, Vol. 97 (2018) Following the standard procedure of Backlund (1996), we set traps in the morning, checked them in the afternoon, and reset them to trap overnight. All mammals captured were identified; species, location (coordinates), and date of capture were recorded. Species surveys were recorded from all sites in spring, summer and fall, with minimal winter trapping. Trapping on the LTIR occurred in 2011 and 2012, and on the SRIR in 2014 and Catch rates were calculated to determine trapping success. Survey data were also analyzed to compare trapping success between years at each reservation and average trapping success between the two reservations. Lake Traverse data were normal and comparisons between 2011 and 2012 were made using a paired t-test. A Wilcoxon Signed Rank nonparametric test was used to compare Standing Rock 2014 and 2015 abundance data. Sample sizes between average catch rates for the LTIR (2011 and 2012) and average catch rate for the SRIR (2014 and 2015) were different and because data were not normally distributed for the SRIR, a nonparametric Mann-Whitney U Test was performed to compare LTIR vs SRIR means. RESULTS Eighty-one individuals in 7 species were trapped in 3950 trap nights on the LTIR in 2011 and 2012 (Table 2), producing a catch rate of catches per trap night. Paired t-test results showed that abundances in 2012 did not significantly differ from that of 2011 (t = ; P > 0.05). Deer mice were the most common species sampled, comprising over 44% of the total catch followed by white footed mouse at 19% and meadow vole at 17.7 %. Uncommon species were the masked shrew, 1.3%, and the meadow jumping mouse, 7.6%. Table 2. The number per 100 trap nights of small mammal species caught on the Lake Traverse Reservation in 2011 and Species Number/ 100 Trap Nights Average Per 100 Trap Nights Peromyscus maniculatus (deer mouse) Peromyscus leucopus (white footed mouse) Microtus pennsylvanicus (meadow vole) Blarina brevicauda (northern short-tailed shrew) Zapus hudsonius (meadow jumping mouse) Sorex cinereus (masked shrew) Ictidomys tridecemlineatus (13 lined ground squirrel) Total small mammals per 100 trap nights

5 Proceedings of the South Dakota Academy of Science, Vol. 97 (2018) 87 On 2,929 trap nights in 2014 through 2015, we caught 197 individuals of 9 species of mammals on the SRIR (Table 3), producing a catch rate of catches per trap night. Wilcoxon signed-rank test results showed that abundances did not differ between 2014 and 2015 (Z = ; P > 0.05). Deer mice and meadow voles were the most common. The prairie vole, hispid pocket mouse, and plains pocket mouse, Reithrodontomys montanus, were the least common. The hispid pocket mouse and the plains pocket mouse are species of Conservation Priority (Level III) (IUCN/UNEP/WWF). The eastern cottontail (Sylvilagus floridanus) was also documented in our trapping regimen and was common throughout the reservation. Table 3. The abundance (per 100 trap nights) of small mammal species caught at the Standing Rock Indian Reservation in 2014 and Species Number/ 100 Trap Nights Average Per 100 Trap Nights Peromyscus maniculatus (deer mouse) Microtus pennsylvanicus (meadow vole) Microtus ochrogaster (prairie vole) Peromyscus leucopus (white footed mouse) Ictidomys tridecemlineatus (13 lined ground squirrel) Sylvilagus flordianus (eastern cottontail) Reithrodontomys montanus (plains harvest mouse) Perognathus flavescens (plains pocket mouse) Neotoma cinerea (bushy tailed wood rat) Total small mammals per 100 trap nights Average total small mammals per 100 trap nights were compared between the LTIR (2.069) and the STIR (6.959). Mann-Whitney U test results showed that small mammal abundances were not significantly different between the two study sites (Z = ; P > 0.05). DISCUSSION These data present some interesting challenges. Our statistical analysis showed no differences in small mammal species diversity and abundance between LTIR and SRIR, most probably due to small sample size. Nonetheless, SRIR had an abundant and diverse population of predators that depend heavily on small mammals especially raptors (e.g., red-tailed hawks (Buteo jamaicensis), northern harriers (Circus cyaneus), rough-legged hawks (Buteo lagopus), ferruginous

6 88 Proceedings of the South Dakota Academy of Science, Vol. 97 (2018) hawks (Buteo regalis), golden eagles (Aquila chrysaetos), and snakes (e.g., prairie rattlesnake (Cotalus viridis), gopher snake (Pituophis catenifer sayi)) while these were nearly absent on the LTIR (personal observation). This suggests that SRIR has many small mammals and LTIR does not (although there are other possible explanations, especially for the absence of small mammal dependent predators on LTIR). Moreover, we observed large amounts of unexploited small mammal food resources especially acorns and diverse seeds accumulating in the environment at LTIR, which also supports the conclusion that the small mammal population is very low at LTIR. Although small mammal species abundance did not differ statistically between survey years on LTIR or SRIR, and abundance did not differ statistically between the two sites, provisionally, we conclude that the sites are different ecologically. Overall catch rates and trophic evidence suggest that SRIR has a relatively more abundant small mammal fauna than LTIR. According to an extensive review of the literature by Mills et el. (2009), over a sample of more than a million trapnights in a longitudinal study in North America, the average catches per trap night for deer mice was more than 4% (0.044 catches/trap-night). At 6.7%, catch rates at SRIR were 52% above average. Consequently, the SRIR likely has a greater than average small mammal abundance. In contrast, the LTIR, which had a catch rate of 2.0%, only 45% of the average cited by Mills et al. (2009) and only 30% that of the SRIR, is likely to have a lower than average small mammal abundance. This low catch rate, combined with the almost complete lack of small mammal-dependent predators and the large amount of small mammal forage accumulating in the environment strongly suggests that LTIR has a very low absolute abundance perhaps even a troublingly low absolute abundance. ACKNOWLEDGEMENTS As we continue to serve as Standing Rock Game and Fish Department biologists, we would like to thank the USFWS for Tribal Wildlife Grant program and the resultant funding on both Standing Rock Indian Reservation and the Sisseton Wahpeton Oyate Indian Reservation. It has raised our awareness for the diversity, abundance and critical attention we must direct to our small mammal populations in addition to the other grassland species that occupy these reservations and existing habitats. We thank Director Kelly and Alvah Quinn for their significant insight throughout both these studies. We thank Tracy Dodson, Barry Betts, Cabe Debower, Dave Jenson and Hunter Smith for their help in the field collections. We would also like to thank our four reviewers for helping move forward in publishing our findings as this paper has evolved. LITERATURE CITED Backlund, D Small mammal survey on three range units of the Cheyenne River Indian Reservation, South Dakota. In Cheyenne River Sioux Tribe

7 Proceedings of the South Dakota Academy of Science, Vol. 97 (2018) 89 - Prairie Management Program, Cheyenne River Sioux Tribe Prairie Mgmt. Prog. Eagle Butte, S.D. Biological Services A Study of the Armstrong County Air to Air Gunnery Range. Biological Services, Inc. Chamberlain, S.D. Chapman, S. S., J.M. Omernik, J.A. Freeouf, D.G. Huggins, J.R. McCauley, C.C. Freeman, G. Steinauer, R.T. Angelo, and R.I. Schlepp Ecoregions of Nebraska and Kansas (color poster with map, descriptive text, summary tables, and photographs): Reston, Virginia, U.S. Geological Survey (map scale 1:1,950,000). Davidson, A.D., J.K. Detling, and J.H. Brown Ecological roles and conservation challenges of social, burrowing, herbivorous mammals in the world s grasslands. Frontiers in Ecology and the Environment 10(9): Environmental Profile. SD, ND. Standing Rock Sioux Tribe. Available from: [Cited July ]. Millien, V., S.K. Lyons, L. Olson, F.A. Smith, A.B. Wilson, and Y. Yom-Tov Ecotypic variation in the context of global climate change: revisiting the rules. Ecology Letters 9: Mills, J.N., B.R. Amman, and G.E. Glass Ecology of Hantaviruses and Their Hosts in North America. Vector-Borne and Zoonotic Diseases 9(00):1-12. Moritz, C., J.L. Patton, C.J. Conroy, J.L. Parra, G.C. White, and S.R. Beissinger Impact of a Century of Climate Change on Small-Mammal Communities in Yosemite National Park, USA. Science 322: Sampson, F., and F. Knopf Prairie conservation in North America. Bioscience 44(6):

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