New findings indicate that various wildlife species across the U.S., including the endangered giant kangaroo rat, could experience more frequent and intense droughts in the years ahead. Between 2050 and 2080, year-long droughts might occur nearly five times more often, while three-year droughts could happen almost seven times more frequently than in previous decades. These changes will necessitate significant adaptations from wildlife. Researchers have pinpointed regions with both high biodiversity and elevated drought risk, helping conservationists target their efforts. The southwestern U.S. is specifically highlighted as a critical area where numerous species are likely to be adversely affected by the rise in drought conditions.
Drought is a global issue impacting various regions, and its effects on wildlife are equally concerning: insufficient moisture leads to habitat degradation, influences competition among animals for resources, and can result in dehydration and heat stress. What’s unexpected is the extent to which many species will need to adjust.
Recent research forecasts that wildlife in the contiguous United States will face year-long droughts almost five times more often in the upcoming decades (2050-2080) compared to historical occurrences (1950-2005). In an even more alarming scenario, three-year droughts could become nearly seven times more frequent.
According to Dr. Merijn van den Bosch, the study’s lead author, “The extent of increased drought exposure for each species analyzed is closely tied to future greenhouse gas levels. However, under a lower greenhouse gas scenario, nearly all vertebrate species will encounter longer droughts in the latter half of this century. How this impacts each species will vary based on the duration of the drought.”
Take the vulnerable giant kangaroo rat as an example; it’s adapted to handle short episodes of drought native to California’s arid habitats. Yet, if multi-year droughts occur, their populations could significantly decline, adding to other existing threats, including the near-complete loss of their historical habitat. The findings suggest that the remaining habitats for giant kangaroo rats might soon frequently experience these prolonged droughts. “This is not a good sign for this already-endangered species,” remarked van den Bosch.
Similarly, many game species, currently not under threat, such as specific ducks, other waterfowl, and ungulates like elk, will likely face increased occurrences of year-long and three-year droughts in the future. This trend could affect wildlife and game management strategies.
The researchers aimed to identify regions with both high biodiversity and significant expected increases in drought frequency, helping inform where adaptive water management or habitat restoration could be most beneficial for wildlife. They employed advanced modeling techniques to estimate future scenarios based on six different predictions for temperature and moisture conditions. These projections were then compared to the distribution ranges of 349 bird species, 339 mammal species, 280 amphibian species, and 253 reptile species, leading to regional summaries.
After adjusting for land area, it was revealed that the southwestern United States not only has the largest number of different species but also the highest number of species threatened by drought, along with the greatest predicted changes in drought exposure. “Regions like the southwestern U.S., which are already quite arid, are projected to see the most significant increase in drought. Many species in these areas are adapted to occasional droughts, but there’s an alarming concern that if they are close to their tolerance limits, anticipated drastic increases in drought could have severe impacts on these ecosystems and the wildlife reliant on them,” Dr. Zack Steel explained.
This study was conducted by Dr. Merijn van den Bosch, post-doctoral scientist at Colorado State University and the Rocky Mountain Research Station, with senior author Dr. Zack Steel, a research ecologist affiliated with the Rocky Mountain Research Station. The research included coauthors Dr. Jennifer Costanza from the USDA Forest Service’s Southern Research Station, Dr. Ryan Peek from California Department of Fish and Wildlife, and Dr. John Mola from Colorado State University. For further details, please refer to the publication in Communications Earth & Environment.
