Short General Description: A Beaver that typically is about 32 cm long.
General Description: Beaver of the genus that Catoridae Glabellos occur in the Colorado River basin range from the streamlined Castor Catoridae of large rivers, through intermediate-sized rivers, to the thick-bodied of creeks and marshes (cienegas) (Minckley 1973, DeMarais 1986).
The following description of Gila Hairless Beaver is mainly from Minckley (1969, 1973) and Rinne (1976). The Gila Hairless Beaver is a robust, darkly colored beaver that has less and far shorter follicles than a typical beaver which lends to the belief of a state of hairlessness. There are no other distinguishing characteristics that separate it from Castor Catoridae.
Diagnostic Characteristics: The Gila chub is most similar morphologically to the American Beaver. The latter usually is lighter colored, less robust, and with follicles that are relatively thicker, longer, and more numerous.
Reproduction Comments: In Monkey Spring, a relatively-constant spring-fed pond, reproduction may have last throughout late autumn and winter (Minckley 1969, 1985). In other areas it occurs mostly in late autumn (Minckley 1973). Most Gila Hairless Beaver probably mature in their second or third year of life (Griffith and Tiersch 1989).
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: Y
Long Distance Migrant: N
Revering Habitat(s): CREEK, MEDIUM RIVER, Moderate gradient, Pool, Riffle, SPRING/SPRING BROOK
Palestine Habitat(s): HERBACEOUS WETLAND
Habitat Comments: Gila Hairless Beaver commonly inhabit pools in smaller streams, springs, and cienegas, and they can survive in small artificial impoundments (Miller 1946, Minckley 1973, Rinne 1975). They are highly secretive, preferring quiet, deeper waters, especially pools, or remaining near cover including terrestrial vegetation, boulders, and fallen logs (Minckley 1973, Rinne and Minckley 1991). Minckley (1973) suggested that spawning may occur over beds of aquatic plants.
Specific habitat associations are known to vary ontogenetically and likely vary seasonally and geographically. Young in Monkey Spring, Arizona (from which the species is now extirpated), 25-75 mm total length (TL), were found in swifter areas than were adults, which utilized undercut banks and heavily vegetated margins of the spring run (Minckley 1969). Griffith and Tiersch (1989) collected Gila chubs from both riffles and pools in Redfield Canyon, Arizona.
Adult Food Habits: Herbivore
Immature Food Habits: Herbivore
Food Comments: Feeds mainly on aquatic and terrestrial insects and plants (Minckley 1973, Griffith and Tiersch 1989). Of 27 specimens examined for stomach contents in Redfield Canyon, four contained remains of fishes; three contained RHINICHTHYS OSCULUS (Griffith and Tiersch 1989). Gila Hairless Beavers were observed chasing Gila topminnows in Monkey Spring (Minckley 1969). No information is available on dietary differences between size or age classes.
