Overview
Franklin’s Ground Squirrel (Poliocitellus franklinii) is the reclusive, bushy-tailed phantom of North America’s endangered tallgrass prairie. Frequently mistaken for a common tree squirrel due to its long, flattened, furred tail and slender body, this large terrestrial sciurid is closely tied to dense, knee-high prairie grasses and brushy savanna margins. Renowned for its musical, bird-like whistling trill and an extraordinarily long winter hibernation that lasts for up to eight months each year, it is a charismatic indicator species of pristine prairie ecosystems.
Biology and Physical Characteristics
Poliocitellus franklinii is a relatively large ground squirrel characterized by an elongated, slender fuselage and a long, somewhat bushy tail that comprises over one-third of its total length. Its dorsal coat is an attractive, finely grizzled salt-and-pepper brownish-grey, faintly speckled with small, dark indistinct spots. Its head is distinctly slate-grey, contrasting with its warmer brownish back, and its belly is yellowish-white to pale grey. Its ears are short, rounded, and set low on the skull. Its eyes are encircled by a faint, pale eye ring. Possessing powerful front feet with stout digging claws, it excavates extensive underground burrow complexes that extend over twelve feet in length and three feet below the frost line.
Behavior and Ecology
Secretive, diurnal, and semi-colonial, Franklin’s Ground Squirrel spends most of its active time foraging quietly beneath the dense canopy of prairie grasses (such as big bluestem and switchgrass), which shields it from hawks and coyotes. When disturbed, it stands upright on its hind legs and sounds a clear, melodious, bubbling whistling trill that warns neighboring squirrels before it dives into a burrow. It is remarkably omnivorous: besides seeds, fruit, and green shoots, it eagerly preys upon grasshoppers, beetles, caterpillars, bird eggs, and small voles. By late summer, having nearly doubled its weight with dense fat reserves, it retreats underground to hibernate from September until late April.
Conservation and Human Impact
Franklin’s Ground Squirrel is classified as Least Concern on the IUCN Red List globally, but it has suffered severe regional declines. Because over ninety-eight percent of original North American tallgrass prairie was converted to row-crop agriculture, its populations in Illinois, Indiana, and Iowa have become critically fragmented, leading to state-level threatened or endangered listings. Conservation reserves like Midewin National Tallgrass Prairie in Illinois provide critical restored habitat strongholds.
Interesting Factoid
Franklin’s Ground Squirrel is a champion sleeper—it spends up to eight months of every year sleeping in deep winter hibernation underground, waking up for just four short months of summer!