Western Deserts

Western Deserts

The contiguity of the Sonoran, Mojave, and Great Basin deserts, each with distinctly structured assemblages, creates an ideal place to study whether 20th century climate change has differentially impacted species’ assemblages. Over the last 50 years, this region has experienced a large increase in average annual temperature (greater than 2 C° in some locations), and is predicted to become increasingly warm and arid in the future. In the desert, many bird and mammal species operate at the edge of their physiological tolerances, and the projected increase in climatic extremes increases the chance of mortality from overheating and evaporative water loss. Moreover, although these deserts have experienced less land-use conversion than most regions of the U.S., they are now at the forefront of development by the renewable energy sector. This combination creates an urgent need to understand the current distribution and status of desert birds, and their long-term responses to anthropogenic disturbances.

From 2015-2017, we will be quantifying the effects of climate and land-use change on desert species and communities. We will resurvey birds and mammals at 105 sites in the Sonoran, Mojave, and Great Basin deserts that were sampled for avian diversity in the early 20th century by Joseph Grinnell and many colleagues at UC Berkeley’s Museum of Vertebrate Zoology. The Grinnell era surveys were performed from 1904 to 1945 on protected lands, and provide a snapshot of desert ecosystem health prior to human-induced warming.

Our goal is to decompose the relative importance of physiological limits, life history traits, species interactions, and habitat change on site-level turnover. For the Desert Southwest region that has already experienced substantial warming, we ask:

  1. To what degree are differences in site-level turnover among bird species driven by physiological limitations, climatic variation, habitat change, species interactions, and species traits?

  2. Has recent warming resulted in individualistic or community shifts in species composition?

Avian resurveys will be led by Kelly Iknayan, a doctoral student in Steve Beissinger’s lab and the MVZ. MVZ’s Jim Patton will lead the mammal resurvey team. Collaborators include colleagues at the San Diego Natural History Museum (San Jacinto Resurvey), University of New Mexico, and U.C. Santa Cruz.

Working closely with National Park staff, planning for resurvey work in these regions began in 2010. Specimen records from MVZ and regional institutions and field notes and images within MVZ’s archives were compiled. Projects highlighting specimens and media associated with each of the parks can be found below at:

Death Valley NP
Great Basin NP
Joshua Tree NP
Lake Mead NRA
Mojave NP