BS in Biological Sciences
Biological Sciences Department
The invasive species, Veldt grass (Ehrharta calycina), has come to dominate coastal dune shrub vegetation along the Central Coast of California. Along with creating many land management obstacles, this grass has become dominant in the open habitat of Lompoc Kangaroo Rats (Dipodomys heermanni arenae). It is hypothesized that, due to a lack of suitable kangaroo rat habitat, during the breeding season months of March and April, there will be significantly fewer reproductively active females in areas of relatively high Veldt grass cover as opposed to relatively low Veldt grass cover. This study used data from a long-term demographic study on Dipodomys heermanni arenae trapped in the Guadalupe-Nipomo Dunes National Wildlife Refuge. Two logistic regression analyses and two chi-square analyses were performed to test for the relationship between number of reproductively active females, Veldt grass cover, and year. After finding significant effects of year on the proportion of reproductive females in each grass level, the correlation between grass level and the proportion of reproductive females was not significant (but was suggestive of a possible trend of a larger proportion of reproductive females as grass level increased from low to high). These results could be indicative of a positive correlation between kangaroo rat habitat quality and Veldt grass presence, though the relationship is confounded with annual variation.