The Mt. Graham Red Squirrel Research Program
The Mount Graham red squirrel (MGRS) is an endangered subspecies found only in the Pinaleño Mountains of Graham County, southeastern Arizona. Reported to be extinct in the 1960s, the squirrel was rediscovered in 1972 and listed as endangered in 1987. The Mt. Graham subspecies has been isolated from other subspecies of red squirrels since the end of the Pleistocene glacial periods approximately 10,000 years before present. S tudies have shown that the Mt. Graham red squirrel differs genetically from the other red squirrel subspecies found in the nearby White Mountains and elsewhere in North America (Sullivan and Yates. 1994. Storm over a Mountain Island. University of Arizona Press, Tucson, AZ).
Initially, some biologists believed that the Mt. Graham red squirrel could only survive in spruce-fir habitat on the mountain range, resulting in an 800 hectare (1961 acre) area of the highest elevations (above 3048 m or 10,000 ft.) of the Pinaleño Mountains being designated as critical habitat. In 1988, the U.S. Fish and Wildlife service designated most of this area as a red squirrel refugium. Access to the refugium is restricted by a permit system administered by the USDA-Forest Service. This action has also served to protect three high elevation cienegas (wetlands). Since 1989, however, significant numbers of red squirrels have been found at lower elevations on the mountains, calling into question the validity of designating only spruce-fir as critical habitat and the effectiveness of the refugium restrictions. Currently, red squirrels are found throughout the mixed-conifer and spruce-fir habitat zones, from about 2375 m (7800 ft.) on the north and east slopes to 3267 m (10,720) on High Peak.
The Arizona-Idaho Conservation Act was passed in 1988, which allowed the construction of an astrophysical observatory on the Pinaleño Mountains within MGRS habitat. As a result, the University of Arizona, one of the financial supporters of the observatory, is required to fund a monitoring program responsible for determining whether or not construction of the Mount Graham International Observatory (MGIO) is having any negative impact on the squirrel population. The MGRS Research Program, a separate entity from the Observatory, keeps track of the red squirrel population within 300 m of the observatory and access road. In addition, two non-construction areas are monitored for comparison as control groups. The Mt. Graham red squirrel and the Pinaleño Mountains have been the center of controversy since the 1980's due to the construction of The Mount Graham International Observatory on one of the highest peaks in the range.
The monitored area, (originally 326 ha) is divided into two habitat types: mixed-conifer forest and spruce-fir forest. The mixed-conifer forest is located below 3050m elevation and is composed primarily of Douglas-fir (Pseudotsuga menziesii), corkbark fir (Abies lasiocarpa var. arizonica), Engelmann spruce (Picea engelmannii), ponderosa pine (Pinus ponderosa), white pine (Pinus strobiformis), and aspen (Populus tremuloides). The spruce-fir is higher in elevation than the mixed-conifer forest and is dominated by Engelmann spruce and corkbark fir. This portion of the Mt. Graham red squirrel population has been monitored since 1989 and has ranged in size from 27 to 229 individuals. Fire damage, insect outbreaks, weather fluctuations and variation in food resources have occurred during the course of study.
The Mt. Graham Red Squirrel Research Program continues to analyze ecological data that have been collected throughout the course of the project. Numerous manuscripts have been published with more in development and available on the Publications tab.
Chronological Events of the Mt. Graham Red Squirrel
(adapted from: Mount Graham Red Squirrel, An Expanded Biological Assessment, Coronado National Forest, February 1988)
9,000-10,000(years ago) -- Pinaleños isolated from other squirrel populations during inter-glacial period years before present.
1880's -- The red squirrel was abundant. Timber harvest began at lower elevations.
1894 -- First scientific red squirrel specimens collected.
1920's -- Lower elevation timber harvest ended. Swift Trail construction started. Red squirrel "sign" was not abundant.
1933 -- Swift Trail was completed to Old Columbine. Timber harvest along Swift Trail began.
1935 -- All tree squirrel hunting was suspended statewide due to perceived low populations.
1940's -- Abert's squirrels were successfully introduced to the Pinaleños. There was some concern over hybridization and competition.
1951-52 -- Red squirrel was uncommon to rare. Abert's squirrels were widespread.
1958-66 -- Red squirrels were thought to possibly be extirpated.
1960's -- Red squirrels were sighted on West Peak and Blue Jay Peak by Forest Service Personnel. The road to High Peak/Emerald Peak was completed with firebreaks. Limited timber harvest began along this road and elsewhere in the upper elevations.
Early 1970's -- At least four red squirrel sightings were reported by Arizona Game and Fish Department and the Forest Service personnel.
1973 -- Timber harvest declined as accessible areas were cut.
1976 -- The Mt. Graham Red Squirrel was listed as Group IV - threatened, by Arizona Game and Fish Department. (Group IV: "species that may be no more scarce than 100 years ago. Restricted distribution. Susceptible to major ecological disturbance").
Mid-late 1970's -- At least 12 red squirrel sightings reported by Arizona Game and Fish Department and Forest Service.
1978 -- Mt. Graham Red Squirrel is listed as Group IV - threatened and unique wildlife, by Arizona Game and Fish Department.
1979 -- Mt. Graham Red Squirrel was determined to be a "priority animal" for status determination by Arizona Natural Heritage Program.
1980 -- An informal survey was conducted by Arizona Game and Fish Department. They reported 5 red squirrels.
1981 -- US Fish and Wildlife Service contracted Arizona Natural Heritage Program to identify all mammals in need of Federal listing. Mt. Graham Red Squirrel was placed on Regional Foresters list of sensitive species. Astrophysical testing began on Mt. Graham.
1982 -- Mt. Graham Red Squirrel was again listed as Group IV - threatened native wildlife, by Arizona Game and Fish Department. Mt. Graham Red Squirrel identified as 1 of 2 "priority 1" mammals in Arizona by Arizona Natural History Program. Mt. Graham Red Squirrel included in Review of Vertebrate Wildlife by U. S. Fish and Wildlife Service, "an animal for which a proposal to list as endangered or threatened might, pending additional biological information, be appropriate". Request that Mt. Graham be considered as future astrophysical site by the Smithsonian. Smithsonian gives permission to continue astrophysical testing.
1984 -- Status surveys for three Mt. Graham mammals, including Mt. Graham Red Squirrel was conducted by Arizona Game and Fish Department. Astrophysical site proposal submitted to the FS.
1985 -- "Environmental data report" on proposed Mt. Graham Astrophysical Site.
1986 -- Mt. Graham Red Squirrel specifically excluded from tree squirrel hunting season by AZ Game and Fish Dept. Mt. Graham Red Squirrel proposed for listing as endangered by U. S. Fish and Wildlife Service. First co-operative midden census conducted. Draft Environmental Impact Statement for Mt. Graham astrophysical area released.
1987 -- Mt. Graham Red Squirrel listed as endangered by U. S. Fish and Wildlife Service. Second co-operative midden census conducted.
1988 -- Midden census and red squirrel studies continued. Legislation was added to the Arizona-Idaho Conservation Act, and signed into law, instructing the FS to allow three telescopes to be built on Mt. Graham without further environmental impact studies; includes mandate for a program to monitor the red squirrel populations around the telescope sites.
1989 -- Monitoring Program for Mt. Graham Red Squirrel (now known as the MGRS Research Program) on Mt. Graham Astrophysical Site was initiated in May but was not fully implemented until August. Construction began on the access road to the astrophysical site.
1990 -- Red squirrel population fell to lowest recorded level in the Spring. Bumper spruce cone crop in the Autumn, squirrel population recovered to near 1986 numbers. Construction on telescopes buildings began.
1991 -- Squirrel population continued to increase despite poor cone crops. Largest recorded population in the Autumn. Construction of telescopes continued.
1992 -- Squirrel population declined from the record numbers. Cone crop was very poor for the second year. Construction of telescopes almost complete. Forest Service builds new campground on Mt. Graham.
1993 -- Squirrel population increased to second highest numbers since census taking started. Two telescopes were completed, the third one was started in December.
1994 -- Squirrel population continued to increase. Environmental organizations filed a federal lawsuit to halt the construction of the third telescope. A permanent injunction restricting construction of the third telescope was imposed by a US District Judge. The University of Arizona appealed the decision but the appeal was denied.
1995 -- Squirrel population dropped slightly in the Spring but recovered to 1994 numbers in the Fall. Federal Court of Appeals rejected the U of A request for a rehearing. Rep. Kolbe introduced legislation to allow for the construction of the third telescope. Legislation allowing construction on the third telescope was added to Interior Appropriations Bill and approved by Congress. President Clinton vetoed the Bill.
1996 -- The Clark Peak fire started on April 24, 1996. Construction for the Large Binocular Telescope foundation began on June 29, 1996. Red squirrel population dropped due to the poor cone crop and the Clark Peak fire.
1997 to 1998 -- Construction of the Large Binocular Telescope continues. Red squirrel numbers drop.
1999 -- Construction of the Large Binocular Telescope continues. Insect outbreaks begin on Hawk Peak, High Peak and Emerald Cienega. Red squirrel numbers increase slightly.
2004 -- Nuttall complex fire burns 12029 hectares
2004 to Present -- Construction of the Large Binocular Telescope continues - electrical power line installed. Major tree mortality in spruce-fir forest on the monitored areas due to insect outbreaks. Squirrel numbers decline throughout 2000 and remains low through 2006, with a slight upturn in population numbers in 2002.
2017 -- Frye Fire burns 19,600 hectares between 7 June and 20 July.