The habitat of the endangered blunt-nosed leopard lizard is determined by an interplay between native shrub cover and invasive grass abundance
Dominant shrubs and invasive grass cover can strongly affect desert ecosystems, particularly lizard populations. Invasive grasses act as a hindrance on federally listed blunt-nosed leopard lizard (Gambelia sila) by impeding movement and their ability to hunt. Conversely, shrubs may positively assist these lizards through thermoregulation and reduced predation. The purpose of this experiment was to determine the ideal habitat characteristics and plant composition for leopard lizards for the purpose of conservation. In 2013-2014, 700 shrubs were surveyed and geo-tagged in known leopard lizard habitat and a landscape-wide survey of residual dry matter (RDM) was conducted. Subsequently, these shrub and adjacent open areas were surveyed over two years for scat to determine an association of lizard to shrub- and landscape-level characteristics.
Annual grass abundance was inversely correlated to shrub density and lizard scat. Scat was found more frequently under shrubs than nearby open areas. There was increased spatial association of lizards and shrubs in select pockets of low annual cover, however, only shrub canopy cover was found related to scat abundance. Our results lend support to the idea that blunt-nosed leopard lizards prefer low annual cover and these lizards may be using shrubs for thermoregulation or cover. Shrubs have commonly been shown to benefit the plant community but our results show that shrub conservation in desert systems has implications for other trophic levels as well. With the current degradation of arid environments, maintenance of native shrubs may have indirect effects on biodiversity, and thus must be considered by landscape managers.