Gardening in Deer Country, Part 2
By Charlotte Torgovitsky
A paradise ruled by Queen Calafia
Two major human caused environmental disasters drastically changed the natural world of a land that was long ago described as a mythical island; a terrestrial paradise ruled by a statuesque and beautiful queen named Calafia.
The first major changes came with the Spanish missionaries who first brought European livestock into California, along with an accompanying host of European annual grasses and forbs. The additional grazing herds were the beginning of tremendous pressure put on our native ruminants, and resulted in permanent changes in the ecology of native grasslands and oak savannahs.
The tanning industry nearly wiped out the tanoaks.
The second disaster occurred with the Gold Rush; when from 1849 to 1855, the largest mass migration in American history caused an explosion in the human population within the state. In that short period of time the population of California increased by nearly twenty-five times, creating environmental havoc, along with an exploitation and degradation of natural resources that dramatically changed the natural environment of the entire state.
Vast herds of Tule Elk; so easily slaughtered while grazing in open areas throughout the great Central Valley, were nearly exterminated; infamously reduced to a mere eight or ten individuals before major efforts were made to save the species. Huge flocks of quail, enormous clouds of seabirds, trout and salmon crowding upstream were also vastly reduced in numbers to support the growing population.
Elk, deer, and antelope were often killed just for their hides, which came to be known as California ‘banknotes’. One firm in San Francisco, in just one year shipped out more than 40, 000 hides. The tanning industry nearly wiped out the tanoaks (Notholithocarpus densiflorus), and all this growth and industry was largely fueled by oak trees felled for firewood.
Deer and California oaks; a special relationship
Oak trees in many cultures around the world symbolize fertility, strength, and symbiosis with the earth; in California the oak woodlands were the refuge that helped save our native deer populations. The Columbian black-tailed deer, because they lived in small family groups rather than large herds, withstood the human onslaught a little better than the elk. But even so, it was decades before their populations recovered, and by then the species had adapted by changing their behavioral patterns, and retreating further into the forests.
The oak woodlands provided protected corridors for travel and migration routes, and the understory shrubs associated with the oaks created protective thickets for young animals, and hiding places from predators. The leafy canopies of the oaks moderate light, temperature, moisture, and wind; providing shelter for the deer during the rainy season, and relief during the heat of summer.
Oaks are the major summer browse for the deer, with leaf and twigs providing up to 40% of their diet. It’s easy to see the ‘browse line’ on older trees, and young oaks often develop a browsed ‘skirt’ before the sapling is able to put on some height. The mistletoe and lichens so often associated with oaks are a source of crude proteins for the deer; but once the acorns drop, usually starting in August; they become the single most important food source for the deer. The size of the mast crop in the fall has been directly linked to the reproductive success of the species in the following year.
It has been estimated that one adult deer will eat about 300 acorns a day, making up more than half their daily food intake. The acorns are a rich food source; with 18% fat, 6% protein, and 68% carbohydrates, plus water and fiber, minerals, amino acids, and vitamins A and C. Acorns are high in tannins, but deer have special enzymes in their saliva that bind to these tannins before the acorns are swallowed, and still more enzymes in their digestive tracts that function to break down the fats and proteins, and allow the animals to accumulate a fatty layer that provides both insulation and energy.
A natural pattern of movement
On my hillside I can observe many of these natural patterns of behavior; the small family groups of deer that spend some of the daylight hours during the dry season foraging in the moister floodplains surrounding Novato Creek, and then travel up through the leafy ravines at dusk to forage on the oaks. I don’t often see the full grown bucks until after the acorns drop; but then these magnificent creatures are right here, next to our house picking up the acorns.
In my garden, situated next to unfenced oak woodlands, there is actually less pressure on the introduced plantings than in many more urban areas with fewer oaks and much more fencing, which restricts and crowds the deer populations. Since much of my garden is as dry as the surrounding woodlands in the summer months, the deer are not terribly interested; and I rarely plant anything new except during the rainy season.
Under the oak canopies I always plant without any intention of providing long term irrigation. I will often sheet mulch the area a year ahead, and sometimes lay down a soaker hose for initial moisture. When I do plant I install DriWater canisters with each shrub. This product is a food-grade gel that is 98% water, and provides a source of moisture for about two months during the dry season. That’s when microbial activity in the soil makes the reservoir of water available directly to the root system. Within two to three summers I remove the canisters, backfill with the native soil, and the plants are now ‘on their own’.
Good shrubs to plant in a dry oak understory are coffee berry (Frangula californica), cream bush (Holodiscus discolor), and golden currant (Ribes aureum). At the edges of the canopy, where the light is a bit brighter I plant coyote brush (Baccharis pilularis var. consanguinea), mountain mahogany (Cercocarpus betuloides) and California buckwheat (Eriogonum fasciculatum). These are all plants that can withstand a bit of deer browsing once they have fully established and increased considerably in size.
Some protective measures
The deer seem aware of changes, and are often just curious, so they notice and sometimes try new plants. Since they have no upper incisors, but an almost prehensile tongue and a ‘pad’ in the upper jaw against which to work the lower incisors; they tear off vegetation. It’s this tearing motion that is most damaging to new plants, especially small ones that can be pulled right out of the ground, and left with the whole root system exposed.
When I do plant something new, especially if it’s a small plant I will protect it until it has had time to establish a good root system. I use dried egg meal, mixed with water and a spoonful of vegetable oil as the surfactant to make a really stinky spray that deters the deer from nibbling on a plant. I have also sprinkled human hair clippings all around a new plant, or applied bloodmeal. These deterrents have to be renewed and inter-changed regularly or the deer become accustomed to them. Hair clippings are sometimes hard to get in large enough quantities, and bloodmeal is too high in nitrogen to be used on native plantings very often.
When I plant out native shrubs that can withstand a bit of deer browsing once they are larger and well established, I put a wire cage around each one. I like to use welded wire fencing with a green plastic coating so that it nearly fades out from view. When the wire is carefully cut all along one edge of welded joins, you have an edge with straight bits of wire that can easily be folded over an opposite welded corner to create a round cage. I’ve found that a three to four foot high cage is sufficient, and in most cases securing the bottoms with five or six earth staples will keep them in place for years. In extreme situations the wire cage can be secured to lengths of rebar hammered into the ground.
Toyon (Heteromeles arbutifolia) is a favorite browse plant on my hillside; the only ones that have survived naturally in the wild spaces have become trees; one specimen has a trunk of about six inches in diameter, and a height of about thirty feet. I tend to leave the cages on my toyon for quite a few years!
Golden currant with its smooth delicate leaves is another shrub that the deer sometimes like to browse; I got a drift of these beautiful shrubs established with the aid of DriWater and cages. In addition I planted lots of hummingbird sage (Salvia spathacea) all around the edges and in between each shrub. By the time I removed the individual cages from each shrub, the salvia had grown in thickly, and spread out quite a lot. These highly aromatic plants, with exceptionally sticky leaves, are despised by the deer; so they now protect the golden currant. I planted ‘Avis Keedy’, a yellow-flowering variety of hummingbird sage, and a drift of a yellow and maroon pacific coast iris in the same area to create a beautiful little scene under a coast live oak (Quercus agrifolia).
Charlotte Torgovitsky is a member of the CNPS Marin Chapter and founder of Home Ground Habitat Nursery, is a naturalist, educator, and garden consultant. You can visit her website and contact her at www.homegroundhabitatnursery.org