PS 47-123 - Prey distribution influences the search strategy of the lizard Aspidoscelis uniparens

Background/Question/Methods

The desert grassland whiptail lizard (Aspidoscelis uniparens) is an all-female species found in the southwest United States and northern Mexico. They are insectivores who find their prey using saltatory search patterns. The efficiency of saltatory search strategies can be linked to prey distribution.

We examined how prey distribution influenced the search strategy of the lizard Aspidoscelis uniparens. We provided supplemental prey to natural populations of A. uniparens in uniform, aggregated, and random distributions, then analyzed search paths with respect to turn angles, movement duration, path straightness, step length and step displacement. We also compared two-step movement sequences to expectations from random processes.

Results/Conclusions

Lizards from aggregated plots stopped often while foraging; they had more short duration moves than lizards from other treatments. Foragers on uniform plots moved at higher speeds than lizards on other plots; they had more steps involving long distances and large displacements. Lizards on random plots had proportionately more convoluted steps than other treatments. Two-step sequences of turn angles differed from random expectations for all treatments. In addition, movement durations during two-move sequences differed from random expectations for all treatments. Lizards adjust their search pattern based on resource distribution.