The annual interagency survey of the endangered Mount Graham red squirrel showed a decrease in the latest population estimate in the Pinaleño Mountains of southeastern Arizona.
The annual survey, conducted jointly by the Arizona Game and Fish Department (AZGFD), Coronado National Forest, and the U.S. Fish and Wildlife Service, resulted in an estimate of 144 squirrels. This is an increase from the 109 squirrels estimated in 2021, but lower than the 156 squirrels estimated after a new survey method was implemented in 2022.
“We saw a big increase last year because of our more thorough survey method, but it doesn’t remove the threats this squirrel still faces, and it will take time for them to recover,” said Holly Hicks, AZGFD’s small mammal project coordinator.
Previous annual red squirrel surveys focused on visiting all known “middens,” or areas where red squirrels store their cones. This method did not systematically detect middens created by red squirrels as they moved to new or different areas on the mountain.
The new method now involves systematically searching for active middens within survey plots that are designed to capture the majority of red squirrel habitat in the Pinaleño Mountains. This enables new middens to be detected as they are created, and activity at these middens is then used to estimate the population size.
“We appreciate the continued support of the Arizona Game and Fish Department, the U.S. Fish and Wildlife Service, the Phoenix Zoo, and all of the agency personnel who helped us work together on the census,” said Bonnie Woods, acting Safford District Ranger for the Coronado National Forest.
Marit Alanen, lead biologist for the Mount Graham red squirrel with the U.S. Fish and Wildlife Service, said: “The numbers this year demonstrate that we need to continue working together to manage the squirrels’ habitat and help the subspecies recover.”
The continuing conservation measures for this endangered species and its habitat include the following: assessment of the remaining habitat, insect pheromone treatments to protect trees, conifer seed collection (including storage and planting), forest stand monitoring/enhancement, reducing food and habitat competitors, captive rearing with partners at the Arizona Center for Nature Conservation, the Phoenix Zoo, continuing life history and translocation/augmentation research through the University of Arizona, and continuing annual survey monitoring.
The subspecies was listed as endangered in 1987. Mount Graham red squirrels live only in the upper-elevation conifer forests of the Pinaleño Mountains and feed primarily on conifer seeds. The subspecies is highly territorial and has lower reproductive rates than red squirrels in other locations.
Other long-term impacts to Mount Graham red squirrels and their habitat include insect infestations, competition with non-native Abert’s squirrels, and poor cone crops caused by drought, all of which influence population size.
The Mount Graham red squirrel population peaked at about 550 animals in the late 1990s, but typically ranged between 200 and 300 individuals until the 2017 Frye Fire devastated much of their habitat.