Landscape Scale and Microhabitat of the Endangered New Mexico Meadow Jumping Mouse in the White Mountains, Arizona

Abstract

Abstract The New Mexico meadow jumping mouse Zapus hudsonius luteus was listed as endangered under the U.S. Endangered Species Act in 2014, with critical habitat designated in 2016. Despite these recent conservation actions, there is a paucity of published information regarding its habitat associations. The taxon is a riparian obligate that occurs along both low-elevation rivers and high-elevation headwater streams in several disjunct areas of the American Southwest. Habitat information from one region might not apply to others. The distribution and habitat preferences of the New Mexico meadow jumping mouse in the White Mountains in eastern Arizona are poorly known. Objectives of this study were to 1) identify and resurvey historical locations in the White Mountains, 2) survey for new populations in areas with potentially suitable habitat in the White Mountains, and 3) use quantitative data to evaluate habitat associations at the landscape and microhabitat scales and to compare habitat at sites where I captured or did not capture the New Mexico meadow jumping mouse. I found 123 historical records of the New Mexico meadow jumping mouse from 21 locations in the White Mountains, indicating a formerly broad distribution. I conducted field surveys and collected habitat data at 35 sites (14 historical, 21 new) and caught 37 (39 total captures) New Mexico meadow jumping mice at 12 sites, including 6 of 12 historical locations surveyed. The overall capture rate was 0.36%, with an average capture rate at sites where it was present of 1.28% (range = 0.25–2.5%). All historical sites where I caught the New Mexico meadow jumping mouse were in the drainage of the Black River. The six new sites included the first records for Nutrioso Creek and Corduroy Creek and confirmed persistence of the taxon in the East Fork Little Colorado River, San Francisco River, and Blue River watersheds. Habitat used by the New Mexico meadow jumping mouse in the White Mountains was similar to that reported for other montane populations, characterized by tall, dense herbaceous vegetation composed primarily of forbs and sedges on saturated soil in close proximity to flowing water. However, there was significantly more cover provided by alders Alnus spp. at capture sites at both the stream reach and microhabitat scales. All sites where I captured the New Mexico meadow jumping mouse had no authorized livestock grazing, and the taxon was more likely to occur at sites where there were no signs of unauthorized livestock grazing. Further, there was a significant positive relationship between alder cover and time since an area was excluded from livestock grazing. The widespread exclusion of livestock from riparian areas in the White Mountains may have contributed to the higher rate of population persistence of the New Mexico meadow jumping mice in the White Mountains compared with the Jemez and Sacramento mountains, New Mexico. Although the overall persistence rate in the White Mountains (47%) was higher than other populations, the population is at risk of further losses due to small, isolated occupied areas and ongoing threats.