DOI: 10.5061/dryad.b2rbnzsk8
title: The ecological role of native-plant landscaping in residential yards to birds during the nonbreeding period

description: Residential yards are a form of urban land use that cover a considerable
 amount of area in cities worldwide and provide important habitat for
 wildlife, especially when landscaped with native plants. Nevertheless,
 most native-plant landscaping and wildlife research in the northern
 temperate regions of the world has been conducted during the spring and
 summer breeding periods, leaving a gap in our understanding of the
 importance of residential yards and native plants as habitats for animals
 during the nonbreeding period. To fill this gap, we quantified the
 ecological role of native-landscaped yards to avifauna throughout Greater
 Los Angeles, California (L.A.) during the winter nonbreeding period, which
 is a time of year when the region hosts a high abundance and diversity of
 migratory and resident birds. We surveyed birds and habitat features from
 October-March of 2020 and 2021 at 22 pairs of native and
 nonnative-landscaped yards plus ten additional native-landscaped yards. We
 had three objectives for our study. First, we compared avifaunal
 communities, including feeding and nonfeeding behaviors, and habitat
 features between native and non-native-landscaped yards. Second, we
 quantified relationships between habitat features and bird richness,
 abundance, and feeding and nonfeeding behaviors — focusing on species
 affiliated with urban or natural terrestrial ecosystems of the region.
 Third, we documented feeding and nonfeeding behaviors by birds with native
 and non-native plants. Native-landscaped yards had a greater cover of
 native trees, shrubs, and herbaceous plants, and a higher cover of natural
 habitat elements, including leaf litter and bare-ground cover. Bird
 richness and abundance — especially bird species affiliated with tree and
 shrub-dominated ecosystems — were greater in native than
 nonnative-landscaped yards. Further, yards with a higher cover of native
 plants supported greater numbers of feeding birds, with individuals
 focusing their foraging behaviors on distinct native trees and shrubs,
 including Quercus spp. (oak), Heteromeles spp. (toyon), Arctostaphylos
 spp. (manzanita), and Salvia spp. (sage). Our results suggested that
 residential yards landscaped with native plants provide important habitats
 for birds during the nonbreeding period and are a viable approach for
 residents and cities if improving conditions for birds throughout the
 annual cycle is a goal.
description: <em><strong>Bird surveys
 and feeding and nonfeeding behavioral
 observations</strong></em>: We conducted three 20-min
 area-search bird surveys from October 2020 through March 2021 where we
 recorded the species and number of individuals using each yard (Watson
 2003). We completed surveys between 06:30 - 11:00 hrs. and visited both
 yards of each pair on the same day to minimize weather and seasonal
 biases.  Additionally, for each bird detected, we
 opportunistically recorded whether the individual was exhibiting feeding
 or nonfeeding behavior. Because most yards were small (Fig. 1), after a
 bird was detected, we observed the individual, while continuing to count
 additional species. We then documented whether a bird exhibited feeding or
 nonfeeding behaviors while in the yard during surveys. Feeding behaviors
 included gleaning for prey items on the surfaces of plants, foraging on
 the ground, feeding on seeds or fruit, obtaining nectar from flowering
 plants, and aerial maneuvers (e.g., sallying) (Wood et al.
 2012). <em><strong>Habitat
 features</strong></em>: We conducted vegetation and habitat
 surveys in each yard during the third round of surveys from January to
 March 2021. We used relevé methods to visually estimate the percent cover
 of vegetation at the ground, shrub, and tree canopy levels (Minnesota
 Department of Natural Resources 2007, Wood et al. 2010). 
 Additionally, we used spatial analysis tools in ArcGIS to
 quantify habitat variables at the landscape scale in two ways (ESRI 2016).
 First, we used the 'measure' tool in ArcGIS to quantify the
 Euclidean distance from the centroid of each yard to the boundary of the
 nearest protected area (e.g., San Gabriel Mountains, Griffith Park, Bolsa
 Chica Ecological Reserve, Ballona Wetlands) and to the nearest urban
 greenspace (e.g., community gardens, urban parks, golf
 courses).  Second, to quantify habitat features at the
 extent of the surrounding neighborhood, we used a light detection and
 ranging (LiDAR) derived data product that provided urban-form data for
 every parcel in Los Angeles County (Galvin et al. 2016). Using a spatial
 join to merge with our sample locations, we included seven variables from
 the parcel-level data: the average land value and the average percent
 cover of trees, grasses, bare soil, buildings, paved, and impervious
 surfaces. 
description: We used R for all data analyses. We have attached R Markdown
 files, with code, adjoining the datasets used for analyses related to our
 objectives. R Core Team. 2017. R: A language and
 environment for statistical computing. R Foundation for Statistical
 Computing, Vienna, Austria. URL https://www.R-project.org/.