This cactus serves as food for many mammals at least in the fruiting period in the fall. Usually only the fruit is eaten, but some pads are chewed by rabbits. The fruit or seeds of this plant are eaten by striped skunks, gray foxes, coyotes, pocket mice, kangaroo rats, wood rats, and probably white-footed mice.
The coyote is the dominant carnivore of the coastal sage flats. Many individuals spend the day in the adjacent chaparral-covered foothills and travel down into the flats at night to forage.
Southern Oak Woodland Association
Major Plants
Alnus rhombifolia
Quercus agrifolia
Ribes indecorum
Rhus integrifolia
Rhus ovata
Rhus trilobata
This association is limited to the Pacific slope of the mountain range, occurs in the mouths of canyons and on the floors of canyons, and extends up the larger canyons to 4000 feet elevation or higher. In a few areas on the flats at the coastal base of the range the oaks replace the coastal sage.
The large oaks forming an overhead canopy and the lack of much undergrowth give the oak woodland a shaded parklike appearance. Few brushy or herbaceous plants grow in the mull-laden soil beneath the oaks. Some grasses, however, are present locally.
Two habitats are found in the oak woodland: the pure oak woodland and the riparian. Much of the oak woodland is in canyons and therefore near streams or seepages. The larger streams have bordering growths of alders, willows, and blackberries, inhabited by meadow mice and shrews that are normally absent from the adjacent oak woodland. Neotoma fuscipes macrotis and Peromyscus californicus insignis are commonly found in the riparian habitat, and Peromyscus boylii probably reaches peak abundance in the stream-side thickets and tangles of plant debris.
The rather open floor of the oak woodland is relatively devoid of mammal life. Peromyscus californicus and Peromyscus boylii, the only ground-dwelling rodents commonly found here, usually are taken near the limited areas of brushy growth, or the shelter afforded by logs and fallen branches. The paucity of shelter for small mammals seems to be an important factor limiting rodent populations in the oak woodland.
In the foothills of the San Gabriels the gray squirrel is restricted to the oak woodland, even though this association may be represented by only a narrow strip of canyon bottom oak trees. The presence or absence of "bridges" of oak woodland between mountains which are centers of gray squirrel populations and nearby ranges has probably been a major factor influencing the present geographic distribution of this animal.