Small Mammal Fauna of Nahant Marsh Davenport, Iowa

Transcription

1 Small Mammal Fauna of Nahant Marsh Davenport, Iowa Final Report By Russ Banwarth Biology Research 402 Dr. Rich Legg April 12, 2005

2 2 Introduction Nahant Marsh, a cattail marsh and sedge meadow, is located at 4220 Wapello Avenue in Davenport, Iowa. Nahant Marsh lies alongside the Mississippi River and includes 177 total acres, but the entire wetland community of which Nahant is part occupies 513 acres. Wetland communities account for 50% of the acreage at Nahant Marsh, including marsh, sedge meadow, and open water habitats. The site is mostly lowland reaching 1-2 meters above Mississippi River levels. The highest elevations on the property are at its southeastern extreme. The wetlands are directly connected to the Mississippi River by three main culverts and the southern end of the property. Backflow into the culverts happens seasonally. The wetlands also are fed by overland flow from several drainage ditches (Nahant Marsh Steering Committee. 1998). The entire wetland community lies on either side of the I-280 corridor, but the Nahant location is limited on the east side of the highway (Figure 1). The Nahant Figure 1: These figures show the location of Nahant Marsh. The picture of Iowa shows the location of Scott County. The figure above shows a close up view of Scott county. The picture to the left shows the location of Nahant Marsh in relation to Davenport, IA.

3 3 property is surrounded by US Highway 61 to the east, railroad tracks to the south, and agricultural fields to the north. A small industrial park including warehousing, packing, and production for aluminum castings and plastics, is located on the north side of the Nahant property. Municipal compost and wastewater treatment plants are located on the south side (Nahant Marsh Steering Committee. 1998). The Nahant Marsh site became the Quad Cities Skeet and Trap Club in Shooting activities resulted in the spread of lead shot and clay pigeons over nineteen acres of the present Nahant property. During the operation of the Quad City Skeet and Trap Club, there were five main shooting platforms overlooking the marsh. The platforms ran parallel with the railroad tracks at the position of the present clubhouse. The platforms allowed shooting over the standing water of the marsh (Patterson, 2004). In 1994, the US Fish and Wildlife Service began investigating sick and dead waterfowl at the marsh. Dead waterfowl were found to have swallowed lead pellets left there from the Quad Cities Skeet and Trap Club. Testing by the Environmental Protection Agency showed that there were over 1000 lead pellets per cubic foot in the top six inches of the soil. This contamination affected approximately 16 (18%) acres of open water, 3 (3.4%) acres of sedge meadow and cattails, and 0.5 (.6%) acres of lowland/woods of a total of about 88.5 acres of wetland habitat (Nahant Marsh Steering Committee. 1998). The US Fish and Wildlife Service demanded a clean-up but the gun club could not afford the clean-up effort so they sold the land to the city of Davenport. The City of Davenport and the Environmental Protection Agency (EPA) contracted to clean-up the Nahant property and to use the land for a natural habitat and educational

4 4 purposes (US Fish and Wildlife Services, 2001). For a fuller account of the history of the site, see the Nahant Marsh Ecological Risk Assessment Report for Nahant Marsh After the transition from the gun club to the educational center, the Nahant Marsh property began assessments testing its progress into becoming a natural habitat. An initial survey of the vascular flora of Nahant Marsh was recently completed. During the summer of 2003, ten different habitat types of Nahant Marsh were studied and mapped by Kathy Schmitt (Figure 2). Schmitt sampled plants along 14 different baseline transects in 10 different habitats. This study was unable to sample all of Nahant Marsh because certain areas, notably in the northern portion, were currently being disturbed by mowing, disking, burning and/or excavating for restoration preparation. Nahant Marsh showed high diversity across habitat types, but within most of the habitats, diversity was low (Schmitt, 2003). Little documentation of Nahant Marsh fauna exists. A study done by Jennifer Anderson documented the amphibians of Nahant Marsh and a bird list was recorded for the Audubon Society. Various animals were documented by observation in the Nahant Marsh Ecological Risk Assessment Report. Only three species of mammals were mentioned in the report: the Deer Mouse (Peromyscus maniculatus), Masked Shrew (Sorex cinereus), and a vole (Microtus sp.) (Coffey, 1998). The purpose of my study at Nahant Marsh will be to create a small mammal species list for Nahant Marsh. Based on a general distribution of mammals in Iowa, and habitat considerations, a broad range of small mammals can be expected at Nahant Marsh. Trapping strategy can be directed toward the small mammals that are known to inhabit the area. Small mammal species documented in Scott County include Sorex

5 5 cinereus (Masked Shrew), Blarina brevicauda (Short-tailed Shrew), Scalopus aquaticus (Eastern Mole), Tamias striatus (Eastern Chipmunk), Spermophilus tridecemlineatus (Thirteen-lined Ground Squirrel), Peromyscus leucopus (White-footed Mouse), Peromyscus maniculatus (Deer Mouse), Synaptomys cooperi (Southern Bog Lemming), Microtus pennsylvanicus (Meadow Vole), Mus musculus (House Mouse), and Rattus norvegicus (Norway Rat) (Bowles, 1975). Figure 2: Aerial view of Nahant Marsh. Black lines represent marsh boundaries. White lines represent different habitat areas. Habitats sampled include: AH1= Arrowleaf Dominant Area, BR1= Bulrush Dominant Area, BW1 = Bottomland Woodlands, CG1 = Rice Cut Grass Dominant Area, CT1 = Cattail Dominant Area, EC1= Ecotonal Cattail, EF1= Ecotonal Fern, EW1= Ecotonal Woodland, MP1-4= Mesic Prairie Restoration Area, SP1= Sand Prairie Restoration Area and WP1= Wet Prairie Restoration Area.

6 6 Mammals, other than the small mammals that this study is directed toward, that are observed during the trapping process also will be documented. Larger mammals that have been observed in Scott County and that may be located in the Nahant location include the following: Didelphis virginiana (Virginia Opossum), Marmota monax (Woodchuck), Sciurus carolinensis (Gray Squirrel), Sciurus niger (Fox Squirrel), Glaucomys volans (Southern Flying Squirrel), Geomys bursarius (Plains Pocket Gopher), Ondatra zibethicus (Muskrat), Canis latrans (Coyote), Vulpes vulpes (Red Fox), Procyon lotor (Raccoon), Mustela frenata (Long-tailed Weasel), Taxidea taxus (Badger), Mephitis mephitis (Striped Skunk), Lutra canadensis (River Otter), Odocoileus virginianus (White-tailed Deer), Sylvilagus floridanus (Eastern Cottontail), and Castor canadensis (Beaver) (Bowles, 1975). This study will contribute to a basic knowledge of the fauna of the Nahant Marsh property. Combined with work on other groups, a full picture of the mammals at Nahant Marsh may be used in the future in evaluating the biodiversity and species richness of the marsh. Materials and Methods Between mid-october and early November of 2004, I conducted eleven trapping sessions at Nahant Marsh. Each trapping session sampled one habitat area, although some habitats were sampled more than once (Figure 3). Fifty traps were set during each session using the paceline method. The paceline method places traps at regular intervals along a straight line called a trapline (DeBlase and Martin, 1974). Traps were not placed exactly on the transit line, if such position was not suitable for small mammals. If in reasonable reaching distance, some of the likely places for trap siting included woody

7 7 debris, rocks, bushy and grassy areas, fallen dead trees, and fence lines. Traplines were kept away from the edge of the habitats to decrease the chance of running a trapline into another habitat type. Figure 3: Aerial view of Nahant Marsh. Black and white dotted lines represent the boundaries of the marsh. Solid black lines represent the different traplines in the habitat areas that were sampled. The symbols used in the figure are explained in the legend of Figure 2. All sampling sites included fifty traps except the bulrush dominant area (BR1). This area only contained twenty-five traps due to significant rainfall immediately prior to the trapping session resulting in too much standing water to run a standard trapline. The bulrush sampling area was moved northeast of Kathy Schmitt s location

8 8 due to the migration of habitat area caused by seasonal changes in water level or longterm fluctuations due to natural drought cycles (Thompson, 1992). The arrowhead dominant (AH1) habitat area was not sampled due to the lack of presence of arrowhead species. Mesic prairie and bottomland woodland habitat areas were sampled twice because of capture success in the area, widespread distribution of this habitat on the Nahant Marsh property, and their provision of a prime environment for small mammals. The starting and endpoints of each trapline were marked using a stake and colored ribbon. Sampling utilized three types of traps: Museum Specials, rat traps, and mouse traps (Figure 4). The largest, the rat trap, is effective at catching rats, chipmunks, ground squirrels, and other small ground dwelling mammals. The smallest trap, the mouse trap, and the Museum Special, which is slightly smaller than a rat trap, are ideal for catching mice, voles, and shrews. Pairs of traps were set approximately 5m apart. The length of the trapline, and the number of traps in the trapline, depended on the shape and size of the habitat being sampled. Most sample sites had two parallel 50m traplines consisting of both mouse traps and museum specials. Traplines were placed approximately 20m apart. A 50m rat trapline was placed midway between the mouse traplines. In longer and more narrow habitats, one mouse trapline of about 100m was used with a 50m rat trapline 10m away. Traps were placed flat on the ground in an area that was fairly level. Twenty museum specials, ten rat, and twenty normal mousetraps were set in each habitat area unless the habitat was too small. For sampling sites for which the total area precluded a full-length trapline of fifty meters, traps were placed with the same spacing to the full extent of the site. A GPS system was used to document where traplines were set, noting the longitude and latitude coordinates for each site.

9 9 Figure 4: These are the three types of traps used. From right to left is the rat trap, museum special, and mouse trap. Traps were set and baited with a dab of peanut butter and oat mixture just before dusk since small mammals are mostly nocturnal. Ants and other small invertebrates will eat the bait if the traps are set too early in the day, and these small animals can ruin trapped specimens if the traps are not checked soon after dawn (DeBlase and Martin, 1974). Specimens were put into zip-lock bags and labeled with their respective habitat area. Specimens were then taken back to the school lab and frozen for subsequent identification. Results and Discussion Specimens were identified to species by means of pelage patterns, hindfoot, total body, tail, and ear lengths. There were thirty-six total specimens captured: 31 Peromyscus leucopus, 3 Blarina brevicauda, and 2 Microtus pennsylvanicus. Of the 36 specimens caught, 27 were caught with the Museum Specials and the remaining nine were caught using mouse traps. Rat traps were unsuccessful in catching any specimens.

10 10 Identifications of the Peromyscus sp. that I caught, Peromyscus leucopus disagreed with the species identified in the Nahant Marsh Ecological Risk Assessment Report, Peromyscus maniculatus. Discrimination between P. leucopus and P. maniculatus is very difficult. Simple field characteristics may not be reliable enough to distinguish the two species. It is possible that the specimens identified in the Nahant Marsh Ecological Risk Assessment Report were not accurately identified due to the similarities between P. leucopus and P. maniculatus. The Deer Mouse, Peromyscus maniculatus, is a small rodent with large black protruding eyes. Its tail is moderately to well-furred and is from one-third to less than one half of the total body length. Each front foot has four clawed toes and a small thumb, while each hindfoot has five clawed toes. The coloration of both sexes for P. maniculatus is generally grayish to reddish on the sides, and can be with or without a darker area in the middle of the back. The lower face and underparts, including the feet, are usually white or grayish. The base of the hairs on the back and belly are grayish. The tail is dark like the back and is sharply contrasted to the light belly below. The young have grayish black fur that changes to duller and paler brown before adulthood (Schwartz and Schwartz, 1981). The White-footed Mouse, Peromyscus leucopus, is very similar to the Deer Mouse except for a few distinguishable characteristics. The tail of the White-footed Mouse is generally longer and also lacks the sharp contrast in coloration on the tail. The entire body length and the length of the hindfoot of Peromyscus leucopus are commonly larger than that of Peromyscus maniculatus. Coloration of the pelage of P. leucopus and P. maniculatus are also alike (Schwartz and Schwartz, 1981).

11 11 In addition to general characteristics, identifications can be done in Peromyscus species using a variety of quantitative characters (Hoffmeister, 2002). The field characters used are shown in Table 1. Each specimen was given a species identification according to hindfoot length, and also a separate identification by calculating its ratio of tail length to total body length. Specimens whose ratios were greater than.46 were identified as Peromyscus maniculatus, and those less than.46 were identified as Peromyscus leucopus (Reed, et al, 2004). Habitat type, sex and date of capture were noted for all specimens as seen in Appendices I and II. Table 1: Field Characteristics to Discriminate between P. leucopus and P. maniculatus Characteristics P. maniculatus P. leucopus Hind foot length 16-18mm 18-22mm Tail length 40-65mm 70-85mm Ratio of tail/total lengths To further my knowledge of mammals that could not be observed or trapped, in the early spring of 2005, I photographed mammal tracks, patterns, and other signs in the fresh snow and mud around the Nahant property. The mammals observed during trapping or tracking efforts included Odocoileus virginianus (White-tailed Deer), Procyon lotor (Raccoon), Sylvilagus floridanus (Eastern Cottontail), Scalopus aquaticus (Eastern Mole), Sciurus niger (Fox Squirrel), Felis catus (Feral Cat), Didelphis virginiana (Virginia Opossum), Ondatra zibethicus (Muskrat), and Castor canadensis (Beaver). Observation could not be used to identify bat species; therefore, bats are not part of the observed mammals list.

12 12 Conclusion The species list may not be a complete list of the species living at the Nahant Marsh. The marsh provides prime habitation for many other species that have been documented from Scott County. Possible species that may also be living at Nahant Marsh include those mammals listed in the second column of Table 2. Representative specimens of trapped species were prepared as study skins and will be deposited in the St. Ambrose University mammal collection. Table 2 Species List of Trapped and Observed Mammals Species List of Possible Mammals Living at Nahant Common Name Scientific Name Common Name Scientific Name Beaver Castor canadensis Badger Taxidea taxus Eastern Cottontail Sylvilagus floridanus Bat species Order Chiroptera Eastern Mole Scalopus aquaticus Coyote Canis latrans Feral Cat Felis catus Deer Mouse Peromyscus maniculatus Fox Squirrel Sciurus niger Eastern Chipmunk Tamias striatus Meadow Vole Microtus pennsylvanicus Southern Flying Squirrel Glaucomys volans Muskrat Ondatra zibethicus Gray Fox Urocyon cinereoargenteus Raccoon Procyon lotor Gray Squirrel Sciurus carolinensis Short-tailed Shrew Blarina brevicauda House Mouse Mus musculus Virginia Opossum Didelphis virginiana Long-tailed Weasel Mustela frenata White-footed Mouse Peromyscus leucopus Masked Shrew Sorex cinereus White-tailed Deer Odocoileus virginianus Mink Mustela vison Norway Rat Rattus norvegicus Red Fox Vulpes vulpes River Otter Lutra canadensis Striped Skunk Mephitis mephitis Thirteen-lined Ground Squirrel Spermophilus tridecemlineatus Woodchuck Marmota monax

13 13 Acknowledgements Many people donated their effort and time to provide to my project for which could not be possible without their help. I would first like to thank Dr. Richard Legg, my research advisor, for all his time, energy, patience, and guidance that he gave to direct me through this project. I would also like to thank the Saint Ambrose University Biology Department for the funding and the chance to carry out this research project. Thanks to Andy Axup, who was able to provide me with all the materials needed to complete this project. Thanks to Jodi Patterson, the Nahant naturalist, for her time and knowledge of the Nahant Marsh. In addition, thanks to the people at Nahant Marsh for the opportunity to do research at the facility. I would lastly like to thank Rachel Helle for her knowledge that contributed to the project s completion.

14 14 Literature Cited Bowles, J. B., Distribution and Biogeography of Mammals of Iowa. Lubbock, Texas: Texas Tech Press. Coffey, Mike Nahant Marsh Ecological Risk Assessment Report for Nahant Marsh Davenport, IA. Unpublished manuscript. DeBlase, A.F., and R.E. Martin A Manual of Mammalogy. William C. Brown, Co., Publishers, Dubuque, IA. Hoffmeister, D. F Mammals of Illinois. Urbana, Illinois. University of Illinois Press Nahant Marsh Steering Committee Nahant Marsh Master Plan, Nahant Wetland Ecological Area Davenport, Iowa. Unpublished manuscript. Patterson, Jody, (Nahant Naturalist). Interview. (Fall, 2004). Reed, A. W., Kennedy, P. K., Beck, M. L., Kennedy, M. L Using Morphologic Characters to Identify Peromyscus in Sympatry. The American Midland Naturalist, 152(1), Schmitt, Kathy The Vascular Flora of Nahant Marsh. Unpublished Master s Thesis, Western Illinois University, Macomb, IL. Schwartz, C. W., and Schwartz, E. R. (1981). The Wild Mammals of Missouri. Jefferson City, Missouri. University of Missouri Press Thompson, J. R., Prairies, Forests, and Wetlands: The Restoration of Natural Landscape communities in Iowa. Iowa City, Iowa: University of Iowa Press. US Fish and Wildlife Services. (Sept. 11, 2001). Restoring our Resources: Iowa s Nahant Marsh. Retrieved September

15 15 Field Data of Peromyscus Species Appendix I Specimen # Habitat Date Sex Hind foot Hind foot Total length Tail length Ratio Ratio Ear Area (mm) ID (mm) (mm) ID (mm) 1 MP F 19 L L 14 4 CT M 21.5 L L 13 5 BW F 19 L L 14 6 BW F 21 L L 13 7 BW M 23 L L 14 8J BW M 22 L L 13 9 CT M 21 L L CT M 22 L L EC M 22 L L EC M 22 L L EC M 21 L L EC F 22 L L EC M 21 L L EW F 21 L L EC M 22 L L EC M 22 L L EC F 22 L L BW F 20 L L BW F 21 L L MP M 20 L L MP M 22 L L BW F 19 L L 14 28C BW M 19.5 L L CG F 20 L L CG M 21 L L BR M 22 L L BR F 22 L L CG M 21.5 L L CG M 19 L L BR M 21 L L BR M 22 L L 13 Appendix I consists of all measurements and other data of the Peromyscus species caught during trapping sessions. Specimen number eight was identified as a juvenile and was identified from its dark pelage and small size. Specimen number twenty-eight had a noticeable chopped tail due to unknown reasons.

16 16 Field Data of Blarina and Microtus sp. Specimen # Species Habitat Area Appendix II Date Sex Hind foot (mm) Total length (mm) Tail length (mm) Ear (mm) 2 Blarina brevicauda CT1 10/17/2004 M Blarina brevicauda CT1 10/17/2004 M Microtus pennsylvanicus WP1 10/20/2004 F Microtus pennsylvanicus EC1 10/28/2004 M Blarina brevicauda MP2 11/1/2004 M Appendix II consists of all measurements and other data of the Blarina brevicauda and Microtus pennsylvanicus caught during trapping sessions.