The importance of fluvial geomorphology and watershed restoration for the New Mexico jumping mouse

The New Mexico jumping mouse (Zapus luteus luteus, formerly New Mexico meadow jumping mouse, Zapus hudsonius luteus) is a federally endangered small mammal that persists in isolated populations in Arizona, New Mexico, and Colorado. This riparian obligate requires dense, structurally diverse riparian vegetation and perennial flowing water. Alterations to the natural fluvial conditions of a watershed can directly affect the quality of riparian habitat available. Stream geomorphic data is used to describe the condition of fluvial processes, riparian habitat, and floodplain creation and maintenance. The purpose of this study was to determine the effects of local fluvial geomorphology on use of streams by the New Mexico jumping mouse in the southwest United States. In 2020, we collected geomorphic data from 58 stream reaches in montane meadows and forests in the White Mountains of eastern Arizona. Stream reaches that supported the presence of jumping mice (n = 31), compared to those that did not (n = 27), had a greater median bed material size (D50), greater sinuosity, lower bank-height ratio, channel evolution stage I, IV, or V, lower width-depth ratio and slope, and a greater width flood prone area, meander-width ratio, and entrenchment ratio. D50, sinuosity, and bank-height ratio were strong predictors of presence. Channel evolution stage, width flood prone area, and entrenchment ratio were of moderate predictive importance. Width-depth ratio, stream type, meander-width ratio, and slope were weak predictors. As bank-height ratio increased, the probability of presence of jumping mice at a site decreased. In contrast, as median bed material size and sinuosity increased, the likelihood of use by jumping mice increased. Streams that are actively degrading due to bank erosion can exhibit an increasing bank-height ratio and may also see a decrease in sinuosity and bed particle size (D50) over time. Channel incision can contribute to a drop in the water table, disconnection of the channel from the historic floodplain, and shift the plant community from riparian to upland associated species. Riparian areas are an important resource, especially in the arid Southwest. Changes in habitat management should incorporate watershed restoration actions that improve long-term channel stability, eliminate sources of degradation, and support geomorphic and hydrologic conditions that are foundational to the creation and maintenance of riparian habitat