Got a couple of questions---are your Rose of Sharon cuttings, or rooted plants? What about roses, specifically mutabilis and Zephrine Drouhin? What about the pomegranates? Confederate jasmine? I have various daylilies, some rooted and un-rooted passifloras, mixed daffodil bulbs, maybe a few crinum bulbs, Euphorbia cyparissias, two or maybe three different bee balms, rooted brugmansia cuttings, and I'm sure some other things as well. (*grin*)

In my opinion, nothing less than a tree will survive under the conditions you described with that population density of chickens. There is no low-growing plant that will survive the scratch and pecking.

I would say Amaranthus sp. They aren't native here so I'll leave the exact id to someone else.

There are so many options..... California natives are a natural choice. The Las Pilitas website has a ton of good information to get you started. Look up Ceonothus, Rhamnus (now called Frangula), Ribes, Rhus as a starting point for shrubs for along the fence line. its always good to mix in some deciduous plants. I really like Holodiscus and Physocarpus which have seasonal changes.. I'm sure others can suggest more. But don't feel the need to be a purist and choose only natives, Many Mediterranean and South African plants are from a similar climate and there are many wonderful choices. Grasses soften everything as they move with the slightest breeze. Again, there are tons of choices. Google can be your best friend in checking out possibilities.