Western North American Naturalist Volume 70 Number 2 Article 15 7-9-2010 Records of the northern grasshopper mouse (Onychomys leucogaster) in western Iowa Kristy K. Rickert University of Nebraska at Kearney Keith Geluso University of Nebraska at Kearney, [email protected] Follow this and additional works at: https://scholarsarchive.byu.edu/wnan Recommended Citation Rickert, Kristy K. and Geluso, Keith (2010) "Records of the northern grasshopper mouse (Onychomys leucogaster) in western Iowa," Western North American Naturalist: Vol. 70 : No. 2 , Article 15. Available at: https://scholarsarchive.byu.edu/wnan/vol70/iss2/15 This Note is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Western North American Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Western North American Naturalist 70(2), © 2010, pp. 252–254 RECORDS OF THE NORTHERN GRASSHOPPER MOUSE (ONYCHOMYS LEUCOGASTER) IN WESTERN IOWA Kristy K. Rickert1 and Keith Geluso1,2 ABSTRACT.—In Iowa, the northern grasshopper mouse (Onychomys leucogaster) previously was known only from the northwestern part of the state. Herein, we report records of O. leucogaster from the 1970s and 1980s that extend its dis- tribution into west-central and southwestern Iowa. These records may represent dispersal movements into these parts of Iowa by southward movements from populations in northwestern Iowa or they may represent eastward movements of individuals from Nebraska prior to channelization of the Missouri River. Key words: Onychomys leucogaster, northern grasshopper mouse, distribution, records, Iowa, Missouri River. The northern grasshopper mouse (Ony- and preparator for the specimen from Mills chomys leucogaster) occurs across western and County, and we tracked down field notes and an central North America, including parts of unpublished report for the specimen from Canada, the United States, and Mexico (Hall Pottawattamie County. Voucher specimens 1981). In the United States, O. leucogaster originally were deposited in the natural his- reaches its easternmost limits in Minnesota, tory collection at the University of Nebraska at Iowa, Nebraska, Kansas, Oklahoma, and Texas Omaha; but presently, both specimens are (Hall 1981, Benedict et al. 2000). Throughout its housed in collections at the Division of Zool- range, it inhabits partially disturbed to undis- ogy, University of Nebraska State Museum turbed areas of shrubsteppe, desert scrublands, (UNSM), University of Nebraska at Lincoln. and various types of grasslands (Jones 1964, Record from Mills County Choate and Terry 1974, McCarty 1978, Mulli- can et al. 2005). On 29 October 1978, a male O. leucogaster Distribution of the northern grasshopper (UNSM 19015) was captured “7 miles S of mouse has remained relatively static across most Malvern on county road L66 in Mills County,” of its range during the last half century (Hall and about 80 m north of Fremont County. This Kelson 1959, Hall 1981, Reid 2006). However, in locality is 15 km east of the floodplain of the Nebraska, its distribution has expanded east- Missouri River and 1.2 km west of the West ward, with records beyond the easternmost lim- Nishnabotna River. The individual was captured its reported by Jones (1964). Genoways and in a roadside ditch dominated by brome (Bro- Choate (1970) reported records in Cass County, mus) and surrounded by agricultural fields of and Benedict et al. (2000) described 11 addi- corn or soybeans. The area of the capture site tional records in Richardson, Cass, and Otoe was flat, but with rolling hills 0.8 km to the counties in extreme eastern and southeastern west. Other species of small mammals captured Nebraska. In adjacent Iowa, O. leucogaster only in Sherman live traps in the immediate area has been captured in grassy habitats from Dick- included northern short-tailed shrew (Blarina inson, Lyon, Plymouth, Sioux, and Kossuth brevicauda), house mouse (Mus musculus), counties in northwestern Iowa (Bowles 1975). prairie vole (Microtus ochrogaster), and southern Herein, we report 2 records of O. leucogaster bog lemming (Synaptomys cooperi). from the 1970s and 1980s from west-central Record from Pottawattamie County and southwestern Iowa (Fig. 1). To learn more about habitats and other details at sites of On 4 June 1989, a male O. leucogaster capture, we contacted the original collector (UNSM 29172) was captured at DeSoto 1Department of Biology, University of Nebraska at Kearney, Kearney, NE 68849. 2Corresponding author. E-mail: [email protected] 252 2010] NOTES 253 Lyon Dickinson 96˚ 95˚ 94˚ 93˚ 92˚ Kossuth Sioux 43˚ 91˚ Plymouth IOWA 42˚ Pottawattamie Mills 41˚ 0 100 Miles 0 100 Kilometers N Fig. 1. Distribution of the northern grasshopper mouse (Onychomys leucogaster) in Iowa. Open circles represent pre- viously published records (Bowles 1975), and closed circles represent newer records from 1978 and 1989 presented in this study. The shaded region represents the currently known distribution of O. leucogaster in Iowa. National Wildlife Refuge in Pottawattamie River, or records represent a southward expan- County. This wildlife refuge is located in the sion from northwestern Iowa. floodplain of the Missouri River, about 8 km Northern grasshopper mice in western Iowa west of Missouri Valley, Iowa. This individ- may have originated from populations in eastern ual was captured in a grassland dominated Nebraska prior to the channelization of the by brome that had not been burned for at Missouri River—that is, before construction of least 10 years prior to the date of capture. Gavins Point Dam in the late 1960s near Yank- Grasses ranged from 0.3 to 0.6 m in height. ton, South Dakota. Jones (1964) suggested that The capture site was dry and contained areas the Missouri River and its riparian forests acted of open sand. Other species captured in as a barrier to dispersal of O. leucogaster east- Sherman live traps in nonnative grasslands ward at the latitude of Nebraska. He also noted at the refuge included M. ochrogaster and that this barrier was breached to the north in the western harvest mouse (Reithrodonto- South Dakota, where O. leucogaster occurs mys megalotis). on the eastern side of the Missouri River. Prior to the river’s channelization, movements of river Conclusions channels may have permitted northern grass - Our records of O. leucogaster from west- hopper mice to disperse across the floodplain central and southwestern Iowa are east of of the Missouri River. Historically, rivers with- recent records from eastern Nebraska (Bene- out large-scale alterations to hydrology, such dict et al. 2000) and south of former records as dams, likely enabled small terrestrial verte- from Iowa (Bowles 1975). Explanations for our brates to occasionally disperse across channels new records in western Iowa are unknown, during periods of low flow or when channels but we propose 2 possible scenarios: records were completely dry. During periods of high represent an eastward expansion from Nebraska flow, the lateral movements of channels in prior to the channelization of the Missouri floodplains may also permit movement across 254 WESTERN NORTH AMERICAN NATURALIST [Volume 70 the river. Channels change position mainly as west-central and southwestern Iowa. We sus- blocked flows reroute to paths of least resis- pect that further trapping in western, central, tance. During flood pulses, this rerouting can and southwestern Iowa will show a more wide - move waterways to the opposite sides of land spread distribution of O. leucogaster. masses in floodplains. As river channels change, these areas of land along with their sessile (or We thank Barbara Wilson and Ross Silcock nearly sessile organisms) remain in one spot. for assistance with data on the northern grass - During such events, organisms could be said hopper mouse captured in Mills County. We to “move across” the river, but the river actu- thank Marian Borgmann-Ingwersen for her ally moves around them, yielding individuals unpublished report and field notes on terrestrial on the opposite side of the river. mammals of DeSoto National Wildlife Refuge. A second hypothesis for how individuals Angie Fox prepared Figure 1, Tom Labedz reached west-central and southwestern Iowa is assisted with museum-related matters, and by southward movement from populations of O. Mary Harner assisted with the discussion on leucogaster in northwestern Iowa. This move- river dynamics. Kenneth Geluso alerted us to ment would actually be an extension of the sus- these unpublished records, assisted with track- pected original southeastward movement of O. ing down original data, and provided helpful leucogaster from southeastern South Dakota comments on an earlier version of this manu- into northwestern Iowa (Bowles 1975). We find script. We also thank 2 anonymous reviewers such a scenario more likely than O. leucogaster for helpful comments on this manuscript. originating in Nebraska, especially if individuals reached the Missouri River in eastern Nebraska LITERATURE CITED after its channelization. For example, Benedict et al. (2000) postulated that because of wide- BENEDICT, R.A., H.H. GENOWAYS, AND P. W. F REEMAN. 2000. Shifting distributional patterns of mammals in spread trapping in the region by prior mam - Nebraska. Transactions of the Nebraska Academy of malogists, recent distributional records in east- Sciences 26:55–84. ern parts of Nebraska were likely the result of a BOWLES, J.B. 1975. Distribution and biogeography of mam- recent expansion in distribution rather than mals of Iowa. Special Publications, Museum of Texas undetected populations (see Jones 1964). Tech University 9:1–184. CHOATE, J.R., AND D.M. TERRY. 1974. Observations on Explanations for possible southward move - habitat preference of Onychomys leucogaster (Roden- ments in Iowa associate these movements with tia: Muridae) on the central Great Plains. Transac- habitats created by large-scale changes in land tions of the Kansas Academy of Science 76:263–265. use in the region. Benedict et al. (2000) sug- GENOWAYS, H.H., AND J.R.