The Dry Garden: Prune those trees and shrubs now, before California birds build their winter nests
Birdsong can be piped into gardens. It’s done at the museum and garden complex known as the Las Vegas Springs Preserve. However, for those who prefer the sound of actual birds, perhaps the single most important step that any gardener can take is to stop pruning during nesting season.
Some of us are familiar with the concept of stilling the saws to allow birds to breed, but we follow an Eastern calendar. Unfortunately, that time frame doesn’t apply in Southern California. Whereas bird-nesting in the East is a spring event, it begins here in winter. Two of our most beloved local hummingbirds, Allen’s and Anna's, started nesting in December and will be nesting throughout spring, says Kimball Garrett, collections manager for the ornithology department of the Natural History Museum of Los Angeles County.
Many of the early nesters, he says, are resident (not migratory) birds. The Breeding Bird Species Accounts from the San Diego Natural History Museum include kites, thrashers, sparrows, flycatchers, woodpeckers, mourning doves, hawks and owls among the birds that begin nesting in February.
If you or your gardeners solemnly swear that they would never interfere with a nest -- that they can prune around them -- be skeptical. Exposing a nest is a prelude to its destruction. Moreover, most trimmers won’t see them. Bird nests are only easy to see in children’s drawings, where they usually resemble crows’ nests. There’s a reason why crows build such big baskets: Those birds are fierce enough to fight off marauding squirrels.
The breeding success of many birds lies in secrecy or situation. Hummingbirds position their tiny cups at the very tip of shrub branches. Dangling bush tits' sock nests are distinguishable from foliage only to those who watch the birds make their elaborately cagey ways home.
So, as we head into growing season, the last pruning of anything other than roses should be done in the next couple of weeks or put off until October. Then if you have trees that need a trim, leave them be unless they are damaged by storm and dangerous. They are best left for cutting when the sap is receding in fall, not rising in early winter. A good arborist will understand the request to come back during pruning season.
This leaves us with the trickier proposition of managing shrubs and hedges. My own approach as bird nesting season begins is to inspect the hedges for early hummingbird nests, then to prune strategically only what must come off now, with a firm stop date for all cutting of Feb. 1.
Once the tools are cleaned, oiled and stored, the next challenge becomes how to contain the size of hedges throughout spring and summer. This is best done by spigot, not saw. If your hedges are irrigated during winter, they probably don’t need water and you are producing foliage that will only benefit trimmers and green-waste haulers. Barring a drought, turn off the irrigation to hedges until April, even May. Only newly planted shrubs should need supplemental water during rainy season.
Then as it heats up in late spring, the art is to water enough to sustain the plant. Seek stasis. One good, slow watering a month with soaker hoses or drip lines should be plenty until rains return late next fall. Watering this way has the added benefit of keeping down the weeds.
Having stilled the cutting and watering until September, you will enjoy two added boons. You will have saved enough water to keep a bird bath full. Moreover, birdsong will not have to compete with whining saws.
Recommended reading: Los Angeles Audubon Society Guide to Bird-Friendly Tree and Shrub Trimming and Removal; San Diego Natural History Museum's breeding bird species account.
-- Emily Green
Green's column on sustainable gardening appears here weekly. She also blogs on water issues at www.chanceofrain.com.
Photo credits, from top: Bush tit photograph by Los Angeles Times; Anna's hummingbird photographed by Francine Orr / Los Angeles Times; hummingbird on Susan Gottlieb's yucca plant photographed by Francine Orr / Los Angeles Times.