by Noriko L. Smallwood, Eric M. Wood

As an ecologist, the mega sprawl of cities such as Los Angeles has always made me wonder what happened to wildlife native to the land before development. In the 20th and 21st centuries, humans in Southern California have converted vast natural ecosystems into buildings, houses, roads, agriculture, and other infrastructure and land uses. How did these drastic changes to the environment affect wildlife? How can we mitigate the negative effects of urbanization on wildlife? One opportunity to bring back habitat for wildlife within the cityscape is residential yards, which cover a large percentage of the suburban land cover throughout Greater Los Angeles. However, residential yards throughout the California southland are typically landscaped with exotic trees and shrubs with manicured lawns (hereafter: conventional yard). Conventional yards typically have lower vegetation complexity, a similarity of plant species composition, and increased levels of impervious surfaces. Most wildlife species native to the region are not adapted to the exotic plants and altered conditions in conventional yards. Therefore, one opportunity to potentially mitigate the effects of urbanization and increase the abundance and richness of birds and other wildlife species is to return the yard to a more natural ecosystem by planting native plants (hereafter: native yard) (Photo 1).

Studies in the eastern United States and across the world have begun to show the positive benefits of landscaping with native plants to local fauna, especially during the breeding period. Native yards that provide more complex habitat elements can provide refuge and more effectively interconnect patches of habitat throughout the cityscape. However, few have studied the relationships between native yards and wildlife, including birds, in Southern California, which was a gap that we intended to fill with our research.

Beginning in August 2019, I embarked on a study of how native yards influence urban avifauna. I worked under the guidance of Dr. Eric Wood at California State University Los Angeles. We sought to understand how birds were responding to native yards compared to conventional yards, and what particular features of native yards were driving patterns of avifaunal abundance, richness, and feeding behavior. An important aspect of our work was that we focused our surveys during the winter non-breeding period, which is a time of the year when birds are busy feeding and getting ready for the eventual spring and summer breeding season. Winter is also a time of the year when Southern California supports millions of migratory birds. Therefore, our work was designed to understand whether native yards provided valuable habitat and feeding opportunities to the overwintering bird community, which is critical in ensuring our region is doing its part in supporting bird populations. I surveyed birds and their habitat in native yards and conventional yards from the late fall to early spring of 2020/21. In addition to bird counts and vegetation surveys, I observed and recorded bird foraging behavior on various species of native plants.

We were not surprised but encouraged to find that bird species richness and bird abundance were greater in native than conventional yards (Figure 1A). Further, larger yards with a higher cover of native plants, and natural habitat features, such as bare ground and leaf litter, supported greater numbers of feeding birds, with individuals focusing their foraging behaviors on distinct native trees and shrubs (Figure 1B). One neat finding was that some bird species that are typically associated with natural ecosystems (as opposed to urban environments) were more abundant and only detected in native yards. These included, for example, the California Thrasher (Toxostoma redivivum), the Spotted Towhee (Pipilo maculatus), the Oak Titmouse (Baeolophus inornatus), the Western Bluebird (Sialia mexicana), and the Red-naped Sapsucker (Sphyrapicus nuchalis) — with the latter being an uncommon species to Southern California, but one that happened to occur in a native yard of our study.

While completing my surveys, it was always interesting to find that birds utilized native yards in a way that resembled the surrounding chaparral, oak woodland, and other natural vegetation complexes of the region. Native yards indeed felt like miniature natural ecosystems. Observing birds in native yards felt as though I were watching them while on a hike in nearby natural areas. I detected ground-foraging birds such as California (Melozone crissalis) and Spotted Towhees, Dark-eyed Juncos (Junco hyemalis), Hermit Thrushes (Catharus guttatus), and White-crowned Sparrows (Zonotrichia leucophrys) scratching at mulch and leaf litter to find hidden insects or seeds or fruits to munch on (Photo 2). I noticed birds perched atop native shrubs quickly retreat into understory foliage, a maneuver that would likely not be possible with most conventional yards dominated by lawns (Photo 3). I observed House Finches (Haemorhous mexicanus) and Lesser Goldfinches (Spinus psaltria) swing from flower head to flower head to eat the dried seed of sage plants (Salvia spp.), California Scrub-Jays (Aphelocoma californica) cache Engelmann oak acorns (Quercus engelmannii), and Anna’s (Calypte anna) and Allen’s Hummingbirds (Selasphorus sasin) (Photo 4) feed on nectar from bladderpods (Peritoma arborea), sages (Salvia spp), and fuchsias (Epilobium spp.). Within minutes flocks of bushtits (Psaltriparus minimus) would quickly move and forage through shrubs in yards, while Cedar Waxwings (Bombycilla cedrorum) gobbled fruit from Toyon (Heteromeles arbutifolia) (Photo 5). I noticed the benefits of native yards not only to birds but to other wildlife as well. I observed many Western Fence Lizards (Sceloporus occidentalis) sunbathing and foraging on large rocks and logs in native yards. Bees (Apidea), butterflies (Lepidoptera), and other pollinators appreciated the abundant floral resources and refugia. My observations and our study supported the notion that, in addition to providing habitat and refuge for wildlife within the cityscape, native-landscaped yards in the Los Angeles area were important in structuring a robust and diverse food web, benefiting birds.

Results from our study in Los Angeles alongside other studies on native yards around the world indicate that increasing the amount of native landscaping in urban areas will positively benefit wildlife by providing food resources, cover, and habitat, both during the breeding and non-breeding period. Additionally, as indicated, the vast majority of residential neighborhoods in Greater Los Angeles are conventional, or with homes that use alternative forms of landscaping e.g., xeric-scaping, rocks, etc. Our work strongly suggests that increasing the number of native yards, and likely the number of native plantings throughout Southern California would have a hugely positive effect in allowing bird species and other wildlife requiring native vegetation to expand (or re-take) their range inward towards cities. Also, considering the drought that we are currently in, native plants aid in water conservation as many are adapted to the dry conditions of Southern California. Therefore, there is a money and water savings approach to converting a yard from conventional to native, including taking advantage of rebate programs such as bewaterwise (www.bewaterwise.com)

If you would like to convert your yard into native landscaping, or if you already have a native yard and want to add additional beneficial elements, here are some recommendations for elements to consider including. The list below is based on our research and is also a portion of the necessary elements to have a yard certified as Wildlife Habitat by the National Wildlife Federation (https://www.nwf.org/garden-for-wildlife/certify).

1. Food resources: Plant a variety of native plants that provide different food resources for birds. For example, choose plants with berries [toyon (Photo 5), coffeeberry (Frangula californica), currants and gooseberry (Ribes spp.), elderberry (Sambucus), etc.), and plants with seeds (salvia, buckwheat (Eriogonum spp.), etc.]. Plant a variety of plants that flower at different times of the year for pollinating insects and hummingbirds, some examples include: Fall: fuchsia (Epilobium spp.), Winter: manzanita (Arctostaphylos spp.), lemonade berry (Rhus integrifolia), sugar bush (Rhus ovata), Spring: salvia, lilac (Ceanothus), monkey flower (Diplacus spp.), desert globemallow (Sphaeralcea ambigua), brittlebush (Encelia farinosa), Summer: buckwheat, penstemon (Penstemon spp.), narrow-leaf milkweed, (Asclepias fascicularis), California goldenrod (Solidago californica).

2. Cover/refugia/places to feed:

a. Tree and shrub cover: Trees and shrubs can provide cover and nesting habitat for birds. Trees are a critical component of several natural ecosystems in coastal Southern California. Therefore, we recommend planting a variety of native trees if desired. In particular, we found a high preference of birds towards oaks (Quercus spp.)as feeding substrates. Oaks are one of the most vital trees to wildlife wherever they occur primarily because of the numerous resources they provide e.g., acorns, habitat for insects, cavities for nesting, etc. Our work supports that planting an oak — such as a Coast Live Oak (Quercus agrifolia) in the Los Angeles area, or other Quercus species that may be native to where you reside — will benefit birds and other wildlife. High shrub cover in yards was also beneficial for birds. Shrubs provide cover from predators, protection from the elements, and foraging locations for invertebrate prey, seeds, and other resources.

b. Natural elements: Adding additional natural elements such as logs and boulders not only adds aesthetic appeal but also provides cover and potential nesting habitat. Further, an important finding from our work was that yards with patches of bare ground supported high numbers of ground-feeding birds possibly searching for seeds from nearby plants. Therefore, having a variety of habitat conditions would likely support the higher diversity of birds.

c. Leave the leaves: Leaf litter is an important component of terrestrial ecosystems for nutrient recycling and retention and provides a habitat for ground-dwelling invertebrates or hibernacula for insects in various stages of development during the winter months. Our work pointed toward leaf litter being an important feeding substrate for birds. Thus, we recommend leaving the leaf blower at home and allowing the leaves from your native plants to accumulate in your yard where possible.

We highly recommend the following resources for more information regarding native yards and wildlife habitat: California Native Plant Society (CNPS) (https://www.cnps.org/) and CalFlora (https://www.calflora.org) for endless information on native plants, Theodore Payne Foundation (native plant nursery in Sun Valley (https://theodorepayne.org/), California Botanic Garden (botanic garden and native plant nursery in Claremont (https://www.calbg.org/), Tree of Life Nursery (native plant nursery in San Juan Capistrano (https://californianativeplants.com/), books by Douglas Tallamy (“Nature’s Best Hope,” “Bringing Nature Home”), bewaterwise for rebates on converting your yard (https://www.bewaterwise.com/), National Wildlife Federation for certifying your yard as wildlife habitat (https://www.nwf.org/garden-for-wildlife/certify), Homegrown National Park to add your native yard to the map (https://homegrownnationalpark.org/).

For more on our work, please view our paper at the following link:

https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.4360

Smallwood, Noriko L., and Eric M. Wood. 2023.“The Ecological Role of Native-Plant Landscaping in Residential Yards toBirds during the Nonbreeding Period.”Ecosphere14(1): e4360.https://doi.org/10.1002/ecs2.4360ECOSPHERE21 of 21