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Spatial Distribution of a Population of Texas Horned Lizards (Phrynosoma cornutum: Phrynosomatidae) Relative to Habitat and Prey
Martin J. Whiting, James R. Dixon and Roy C. Murray
The Southwestern Naturalist
Vol. 38, No. 2 (Jun., 1993), pp. 150-154
Published by: Southwestern Association of Naturalists
Stable URL: http://www.jstor.org/stable/3672068
Page Count: 5
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The spatial distribution of a Texas horned lizard population was quantified with respect to habitat and prey. Horned lizard spatial distribution was clustered in three specific areas, whereas ant mounds belonging to their primary prey, Pogonomyrmex barbatus, were randomly distributed in the study area. An analysis of vegetation cover relative to horned lizard spatial distribution suggests that habitat, not prey, governed the spatial distribution of this population. In particular, horned lizards selected disturbed areas where ground cover was less dense. Horned lizards occurred at a density of one lizard/3,636 m2 or nearly three lizards/ha. Pogonomyrmex barbatus mounds occurred at a density of 15.9 mounds/ha, equivalent to about 196,492 ants/ha. Relative to harvester ants, horned lizards occurred at a ratio of one lizard per six ant mounds or one lizard per 74,148 ants. Compared with a previous study in New Mexico, harvester ant density was considerably greater, however, horned lizard density was less. This may be related to prey availability; although ants are less abundant at the New Mexico site, more individuals may be available for consumption due to habitat differences.
The Southwestern Naturalist © 1993 Southwestern Association of Naturalists