The preserve was set aside as a mitigation bank for non-native grassland and Diegan coastal sage scrub with some credits in the bank still remaining to be purchased. Portions of the site were previously graded for homes. The threatened coastal California gnatcatcher will also be protected by conservation of this site. The site has approximately 125 acres of non-native grassland and 28 acres of Diegan coastal sage scrub. Notable species include 4 pairs of coastal California gnatcatchers, mule deer, grasshopper sparrows and road runners.
Restoration includes prescribed fire to remove non-native grasses.
The Center coordinated fires in 1999 and 2000 with the City of Oceanside fire department. To date, non-native grassland cover has decreased dramatically. Other management activities include avian community surveys, small mammal trapping and vegetation sampling. The Whelan preserve is managed by Markus Spiegelberg, under the supervision of CNLM's Southern California Regional Director, Cameron Barrows.