Historic drought across the American Southwest is shrinking the amount of highly suitable habitat for large mammals, a study published in Communications Earth and Environment reports. The researchers used long-term GPS collar data to quantify how drought alters landscapes used by different species.
The team analysed 12 years of tracking data from mule deer, black bears and cougars in Nevada and Utah, covering more than 3,000 animals across a nearly 200,000-square-mile range between 2010 and 2022. The project received federal funding from NASA and drew on data compiled by many groups, with David Stoner credited for help gathering sources.
Findings show that during severe drought each species lost at least 10% of its highly selected habitat: mule deer about 10%, black bears about 14% and cougars about 18%. The study also reported fitness effects—under extreme drought the number of new fawn mule deer per doe can fall by more than 30%.
Authors say drought impacts can cascade from prey to predators. Predators like cougars may be more sensitive because they cannot eat vegetation and must work harder to find food, and lower population densities at higher trophic levels mean effects on individuals can influence whole communities. The researchers argue the results show the value of long-term datasets and the need for coordinated planning to reduce wildlife vulnerability to worsening drought and related climate changes.
Difficult words
- drought — A long period with very low rainfall.
- habitat — The natural area where a species lives.
- quantify — To measure or express amount numerically.
- fitness — An organism's ability to survive and reproduce.
- cascade — A series of effects that follow one another.
- trophic level — A position in the food chain.trophic levels
- vulnerability — The likelihood of being harmed or affected.
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How could coordinated planning help reduce wildlife vulnerability to worsening drought in this region?
- Why might predators like cougars be more sensitive to drought than herbivores? Give reasons from the article.
- What role do long-term datasets play in understanding climate effects on wildlife, based on this study?
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