The endangered Mount Graham red squirrel, a subspecies of squirrel found only in the Pinaleño Mountains of southeastern Arizona, has been surveyed at higher population numbers than anticipated.
The annual interagency population 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 estimated 233 squirrels. This is an exciting increase from the 144 squirrels estimated in 2023.
“We all knew that we were seeing a lot of squirrels and middens during this last survey,” said Holly Hicks, the AZGFD small mammal project coordinator, “but I don’t think any of us expected such a dramatic increase.”
The current survey method, first implemented in 2019, involves systematically searching for active middens within survey plots to census the majority of red squirrel habitat in the Pinaleño Mountains. Typically, one squirrel will maintain one midden, which is considered active if there are signs of feeding and/or stored pine cones. Active middens are then used to estimate the population size.
“This survey process allows us to obtain a more accurate picture of the population numbers,” said Coronado National Forest Supervisor Kerwin S. Dewberry. “We are excited to see that current land management practices being implemented in the Pinaleño mountain range are proving to be beneficial for the Mount Graham red squirrel population.”
The Mount Graham subspecies was listed as endangered in 1987. These red squirrels live only in the upper elevation conifer forests of the Pinaleño Mountains and feed primarily on conifer seeds. They are highly territorial and have lower reproductive rates than other red squirrels. Long-term impacts on Mount Graham red squirrel’s population size and habitat include wildfire, insect infestations, competition with non-native Abert’s squirrels, and poor pine cone crops caused by drought.
The Mount Graham red squirrel population peaked at approximately 550 in the late 1990s. Typically, the squirrel population ranges between 200 and 300 individuals. After the 2017 Frye Fire, however, much of their habitat was destroyed and the population plummeted to approximately 35 squirrels.
“We were all extremely concerned for the subspecies after the 2017 Frye Fire caused the squirrel’s population to drop drastically,” said Marit Alanen, lead Mount Graham red squirrel biologist for the U.S. Fish and Wildlife Service. “So seeing a number now over 200 is really fantastic news.”
Continuing conservation measures by the partnering agencies for this endangered squirrel include:
- Assessment of habitat
- Insect pheromone treatments to protect trees
- Conifer seed collection (including storage and planting)
- Forest stand monitoring/enhancement
- Reduction of food and habitat competitors
- Captive rearing with partners at the Arizona Center for Nature Conservation and the Phoenix Zoo
- Life history and translocation/augmentation research through the University of Arizona
- Annual survey monitoring
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