Rapid Reservoir Inundation Causes Complete Extirpation of the Eastern Collared Lizard (Crotaphytus collaris) Along the Shoreline of Bull Shoals Lake in Northern Arkansas

Abstract

The eastern collared lizard (Crotaphytus collaris) is a large saxicolous predatory lizard, which dwells in patchy, cedar glade environments characteristic of much of the Ozarks. The species can also be found in scattered populations along rocky shoreline habitats of large impoundment reservoirs of northern Arkansas. These lizards time their entrance into and exit from underground, overwintering retreats with decreasing and increasing ambient temperatures of the fall and spring months. During an average spring, several sustained days of warm temperatures from mid-March into April are the primary environmental cues for collared lizards to exit their shelters. Excessive winter/spring precipitation in the Arkansas Ozarks, however, can drastically alter reservoir hydrology of the impoundments on the White River system. In years of catastrophic flood conditions, such as in 2008, the rapid inundation of suitable shoreline habitats preceded the exiting of lizards from hibernation burrows; thus, these populations of collared lizards (i.e., those that occurred along both Bull Shoals and Norfork lakes) were effectively entombed in their hibernation burrows, which putatively resulted in a complete population crash of this species within exposed shoreline environments.