Eleven burros were found dead near Owl Hole Spring in Death Valley National Park this week. The National Park Service is still investigating the cause of death, but they believe a harmful algae bloom in the spring is to blame, according to the park release.
Algae and cyanobacteria occur naturally in the water, and can create a harmful algae bloom when water is slow-moving, warm, and is affected by chemicals from fertilizer or sewage, according to the Centers for Disease Control and Prevention.
The NPS reported all three of those conditions existed at the stagnant Owl Hole Spring this summer.
So far only dead burros have been found, but other animals were likely affected.
“I hate to see any animal suffer,” said Superintendent Mike Reynolds. “The National Park Service is working to remove feral burros from Death Valley, for their own safety and to reduce impacts to native wildlife.”
The NPS warns that the water in Owl Hole Spring should be considered unsafe for humans or pets to drink or touch. In addition, people and pets should not handle any of the carcasses. Park rangers have installed a warning sign in the area.
Burros is a term commonly applied to feral donkeys that live west of the Rocky Mountains. Although approximately 4,000 burros roam Death Valley National Park, they are not a native species in the area. These burros are descendants of animals released by miners decades ago.
Due to lack of funding, roundups and relocations have not been conducted on a large scale since 2005. The park has funding to resume roundups in 2026.
