“The only biodiversity we’re going to have left is Coke versus Pepsi. We’re landscaping the whole world one stupid mistake at a time” – Chuck Palahniuk
I have two favorite California native trees and they are both endangered. The Coastal Live Oak (Quercus agrifolia) and the California Sycamore (Platanus racemosa) are both under threat of being killed off by a new pest called Polyphagous Shot Hole Borer.
Unfortunately, this beetle is not only targeting my favorite natives, but are also found infesting many other common Southern California trees (110 by current estimates), including Avocados, London Plane Tree (a relative of the Sycamore), Palo verde, and Liquidambar, to name a few. There seems to be very little we can do except identify, contain, and very carefully destroy infested trees. I included a link to a PDF sheet that talks about current research and problem that the beetle is causing. Basically, the Shot Hole Borer carries two unfriendly fungi that causes a disease called Fusarium Dieback which chokes off the movement of water and nutrients in the tree.
Click here for a guide to symptoms in various tree species.
Although there are plenty of PhD’s at UC Riverside and the Los Angeles County Department of Agriculture working on the problem, there are no solutions. I have direct experience with this devastating disease which is killing off dozens of mature California Sycamore trees at our new park in Burbank. We conceptualized the park three years ago using the existing Sycamore trees as the primary shade tree. However, today as we begin to construct the park these mature trees are gone because of the borer beetle infestation.
Just as the Eucalyptus Longhorn Borer wiped out the Eucalyptus trees during the 1980’s, this new pest is an another potential beetle that is quietly devastating to our natural and ornamental landscapes. Unfortunately, the researchers are telling us designers to stop using the 110 different species that have been identified to be susceptible to the beetle. The questions remain: which trees will be left for us to include in our designs? And more fundamentally, what are we to do as designers and stewards of our landscapes?
According to the Audubon Field Guide the Brown-headed Cowbird is “known to have laid eggs in nests of over 220 species of birds, and over 140 of those are known to have raised young cowbirds.” – Photo: Rob & Ann Simpson/Vireo
While taking a leisurely walk down the San Gabrielino Trail in the Angeles Forest one might come across a variety of native wildlife. There are sunny patches of light pinks and whites from the freshly blooming California Buckwheat and the soothing sound of a watery creek bed with slender green arroyo willow leaves rustling in the wind along this trail.
Photo: Roxana Marashi
A particular bird catches your eye as it briskly flies from one tree branch to another. It has a brown feathered body with a small black beak, and it appears to be nesting on one of the branches of an Arroyo Willow tree. You take a closer look, and you soon realize that nest does not belong to that bird; it actually belongs to a Least Bell’s Vireo, an endangered species who thrives off of riparian habitat in the Los Angeles basin. The imposter is a Brown-headed Cowbird, and it is known as a brood parasite: a bird that lays its eggs in the nest of others.
Photo: Roxana Marashi
Oddly enough, this bird is a protected native species, even though it is hurting other native bird populations. With a state permit, agencies can set up traps to capture and remove cowbirds from certain areas such as the Upper Buck Gully in the Newport Beach area. Biologists and conservancies have been keeping an eye on these native opportunists and how they behave. It turns out that their method of survival is very successful for them since they used to mix with bison herds when they roamed across the Midwest.
Today, the Brown-headed Cowbird is often seen near cows grabbing a bite of tasty insects off of their backs. Since bison herds always migrate, these birds were unable to survive by building a stationary nest to incubate their eggs, then nurse their chicks for weeks on end until they are strong enough to survive on their own. That is why the Cowbird evolved its brood parasitism strategy, because it was the only way to ensure their species survival.