Unusually large upward shifts in cold‐adapted, montane mammals as temperature warms

Abstract

The largest and tallest mountain range in the contiguous United States, the Southern Rocky Mountains, has warmed considerably in the past several decades due to anthropogenic climate change. Herein we examine how 47 mammal elevational ranges (27 rodent and 4 shrew species) have changed from their historical distributions (1886-1979) to their contemporary distributions (post 2005) along 2,400-m elevational gradients in the Front Range and San Juan Mountains of Colorado. Historical elevational ranges were based on more than 4,580 georeferenced museum specimen and publication records. Contemporary elevational ranges were based on 7,444 records from systematic sampling efforts and museum specimen records. We constructed Bayesian models to estimate the probability a species was present, but undetected, due to undersampling at each 50-m elevational bin for each time period and mountain range. These models leveraged individual-level detection probabilities, the number and patchiness of detections across 50-m bands of elevation, and a decaying likelihood of presence from last known detections. We compared 95% likelihood elevational ranges between historical and contemporary time periods to detect directional change. Responses were variable as 26 mammal ranges changed upward, 6 did not change, 11 changed downward, and 4 were extirpated locally. The average range shift was 131 m upward, while exclusively montane species shifted upward more often (75%) and displayed larger average range shifts (346 m). The best predictors of upper limit and total directional change were species with higher maximum latitude in their geographic range, montane affiliation, and the study mountain was at the southern edge of their geographic range. Thus, mammals in the Southern Rocky Mountains serve as harbingers of more changes to come, particularly for montane, coldadapted species in the southern portion of their ranges.

Wagering with an incomplete deck—refining conservation plans for the New Mexico Meadow Jumping Mouse (Zapus luteus luteus)

“…1). The year 2000 is significant because mean global CO 2 concentrations surpassed 370 ppm and the effects of climate change measurably altered distributions of some North American wildlife (Schneider and Root 2002; Moritz et al 2008; McCain et al 2021). We retained historical records (pre-1951) in the modeling pool (1951–2000) if Z. l. luteus were documented during the recent period (post-2000), indicating persistence during the target modeling period (one locality).…”

Climate Change, Ecosystem Processes and Biological Diversity Responses in High Elevation Communities

“…It is possible, albeit highly speculative, to estimate species risk as a function of their current elevation range and estimates of warming. Thus, if the climate has warmed by 2 • C, the required adjustment of a species whose climatic requirements have not changed would be to move up in elevation by about 300 m. Over the last century, mammals from montane areas have moved up in average elevation by about 350 m based on records obtained from field collections [42]. These distributional shifts approximately align with the increase in temperature (~2 • C) since museum collections began.…”

Elevational diversity patterns of rodents differ between wet and arid mountains

“…Our assessment of effort was necessarily qualitative due to the range of data scales and types used in source studies but considered factors such as the total number of trapnights and/ or specimens examined, the total number of trapped sites and/or specimen localities, the variety of trap types/survey methods used, and the equitability and coverage of effort/data across the sampled gradient. We recognize that species may still vary in detectability (McCain et al, 2021;Rowe et al, 2015), which has the potential to affect observed diversity patterns (Jarzyna & Jetz, 2016). However, robust accounting for species detectability requires consistent distance or repeated sampling protocols and was thus not possible in an analysis that spans so many disparate studies.…”