IRC Helps Master’s Student Conduct Research for Horned Lizard Project

As summer comes to an end, so does the research phase of an important project conducted on Irvine Ranch Natural Landmarks. Collaborating with the Irvine Ranch Conservancy (IRC), a Master’s student has been collecting data this summer to assess changes in the presence of horned lizards and their habitat quality over time.

This research project begins with Nathan Gregory, Senior Vice President & Chief Programs Officer at IRC, who is also a professor at the Jersey International Centre of Advanced Studies and the University of Exeter. Every year, he partners with a student to conduct their dissertation on the Landmarks with support from IRC. This year, Kevin Donnelly was selected as he is pursuing his master’s degree in Island Biodiversity and Conservation. The Landmarks were chosen as the research site due to their status as a “habitat island,” surrounded by urban land, allowing for isolated populations and ideal conditions for this research.

This project serves as a follow-up to a study conducted in the same area during the 1990s. Kevin was asked by the United States Geological Survey (USGS) to reassess the survey from that period, evaluating the suitability of lizard habitats today. In collaboration with USGS, Kevin adopted the same data collection methodology to ensure comparability.

With the assistance of IRC’s Monitoring and Research team, Kevin led the data collection efforts at 11 sites starting in May, including Weir Canyon, Agua Chinon and Limestone. IRC provided the necessary equipment and support for conducting visual, vegetation and insect surveys. The visual surveys involved Kevin and IRC staff visiting various sites to look for horned lizard sightings or signs such as scat. The team also monitored IRC’s camera traps for lizard activity. Additionally, they recorded other species present to determine the presence of horned lizards. Vegetation surveys played a crucial role in comparing habitat changes between the 1990’s and today, with a focus on chaparral habitats preferred by horned lizards. The final area of survey was insects, as this research aimed to monitor the lizards’ food source of native ant species and assess competition with non-native species.

Now that the data collection phase is complete, Kevin will shift his focus to data analysis. Although still in the early stages, a few key findings have emerged. Initial data suggests the presence of horned lizards at six sites while five sites showed no signs. Furthermore, while the 1990’s survey indicated the presence of invasive Argentine ants competing with the lizards’ native food source, this time there was no indication of Argentine ants. Kevin will now delve deeper into examining population changes and habitat quality over time. 

Working with IRC and USGS, Kevin’s findings will be presented in September as part of his master’s program before a comprehensive report is compiled. IRC is excited to continue to work together and see the findings from this project to better understand the horned lizard population on the Landmarks!