If You Love Birds, Plant Scrub Oak

I recently met a woman, I’ll call Margaret for the sake of this article, who doesn’t care about gardening: she doesn’t spend time outside, has no interest in growing her own vegetables–not even tomatoes–she could take or leave flowers.  Her primary concerns in relationship to her landscape are that it not be an embarrassment for the neighbors and that she need put as little energy into landscaping as possible.  We all know have Margarets in our lives.  Some of us may even be Margarets.

I met this woman in front of  the narrow dirt slope that was her front yard after a palm tree and a pine had been removed.  Given the limited space, I had trouble imagining what it must have looked like before, much less how a palm and pine could have looked attractive together.  Talk about an odd couple!  After talking for a few more minutes, in which I desperately searched for any sign of interest in the outdoors, she finally said, “The birds will miss it.”

“The birds will miss what?” I asked

“The pine tree.  The birds were in it all day long.  I would like to re-plant something for the birds.”

I noticed, somewhat surprisingly, that there was a bird bath sitting amidst the dirt of the barren slope.  I had overlooked it before.  Her observations about her lost pine tree were probably correct.  Pine trees, it turns out, support a wide variety of native insects, which in turn support birds, which need the protein insects provide.

Bushtits in Scrub Oak

A little exploration into native ecology reveals that there is a hierarchy among plants in terms of how attractive they are to wildlife in general.  The measure for this  is lepidoptera–that is the butterflies and moths–because these insects have been studied more than any other group.  The more species that like a particular genus of plants, the more essential that genus becomes in supporting animals.   In documenting this, an east coast biologist Douglas Tallamy has come up with a list ranking plants by their ability to support the class Lepidoptera, and thus animals in general.  You can view this link at Wildlife Food-bank (this is my name for it, not theirs).  The pine family, it turns out, are  reported to support slightly over two hundred species of moths and butterflies, which is pretty good.

But topping the list–one can think of it as an All-You-Can-Eat Bird Buffet–are the oak trees.  Oak trees, according to Tallamy’s list, support over five hundred–let me repeat–five hundred species of moths and butterflies.  That is more than double what one can expect from a decent pine tree.  And even though this work was carried out by an east coast biologist, I found out upon doing a little research that the oaks, the great big ones and also their scrubby relations, abound throughout the North American continent.  I found studies talking about their importance in Pennsylvania, in Florida, AND in California.

But this woman had no room on her small plot of land for our large native oaks–the Coast Live Oak, the Interior Live Oak, or the  Canyon Live Oak.  These trees can grow to seventy-five feet tall and have trunks ten feet around.  The only home, in fact, where I have seen a mature Live Oak fit in comfortably in a residential landscape is at the Marston House in Balboa Park.

Scrub Jay in Oak

But this woman had another option, often neglected by homeowners.  She could plant scrub oaks.  These little guys top out at ten or fifteen feet.  Although they probably have deserved their name “scrub” for a reason, they needn’t be in the least bit homely.  With intelligent pruning, these trees can be miniature versions of their grander cousins.  In other words, they can be bon-sai’d.  There are a number to choose from all native to San Diego County:  Quercus, berberidifolia, Quercus dumosa, and wislizenii.  I’ve heard of a fourth, too, Quercus acutidens, but I haven’t been able to verify this one.

If this woman were to plant three scrub oaks on the shallow slope in front of her house, she would create an attractive display of leaf, acorn and bark that would be as appealing to the neighbors as it would be to the birds, that, one would expect, would want to hang out there all day long.  Underneath, I imagine on this dream slope, some of the lovely Pt. Reyes manzanita, which stays low to the ground and gets covered with tiny pink flowers in the Spring.  Small bunches of Douglas  Iris or Snowberry could also help to paint the picture.  And a rock!

Mountain Chickadee on Scrub Oak
Mountain Chickadee on Scrub Oak, common in San Diego