Trans-Specific Drivers of Variation in Forecasted Distributional Changes of Southwest Birds and Reptiles

James R. Hatten, J. Tomasz Giermakowski, Jennifer A. Holmes, Erika M. Nowak, Matthew J. Johnson, Kirsten E. Ironside, Charles van Riper III, Michael Peters, Charles Truettner, Kenneth L. Cole
Posted on: 7/18/2022 - Updated on: 7/14/2023

Posted by




Biodiversity is declining worldwide, and this trend could potentially become more severe as climate conditions change. An integral component of proactive adaptive management planning requires forecasts of how changes in climate will affect individual species. This need has been identified my multiple federal agencies, including the U.S. Fish and Wildlife Service, National Park Service, Bureau of Land Management, and U.S. Forest Service.
The goal of this project was to assist land and wildlife managers in anticipating which species are most vulnerable to changes in climate in the Southwest, and how resources can best be invested to facilitate adaptation. Researchers evaluated the current and future breeding ranges of 15 bird and 16 reptile species in the western U.S. using a new approach that models variables such as temperature and precipitation, terrain ruggedness and soil type, and plants that are commonly associated with each species.
Results showed that two-thirds of the species examined could be expected to experience a decrease in range, while one-third could experience an increase. Climate variables were found to play a bigger role than landscape or plant variables in determining changes in species range. Researchers also found that as available habitat patches for birds and reptiles become more isolated, their ranges also contract. This finding suggests that strategic management actions focused on conserving and restoring connections between habitat patches could help lessen the severity of the projected range contractions.


Hatten, J.R., Giermakowski, J.T., Holmes, J.A., Nowak, E.M., Johnson, M.J., Ironside, K.E., van Riper, Charles, III, Peters, Michael, Truettner, Charles, and Cole, K.L. (2016). Identifying bird and reptile vulnerabilities to climate change in the Southwestern United States: U.S. Geological Survey Open-File Report 2016-1085, 76 p.,

Affiliated Organizations

The USGS is a science organization that provides impartial information on the health of our ecosystems and environment, the natural hazards that threaten us, the natural resources we rely on, the impacts of climate and land-use change, and the core science systems that help us provide timely, relevant, and useable information.

Related Resources