Hummingbirds (Family Trochilidae) are key pollinators in several biodiversity hotspots, including the California Floristic Province in North America. Relatively little is known about how hummingbird diets change throughout the year, especially with regard to how migratory hummingbirds affect resident hummingbirds at stopover sites. In this study, we examine how hummingbird species, migratory status, sex, geographic region and local plant diversity influence floral resource use before, during, and after an influx of migratory hummingbirds (primarily Rufous hummingbirds, Selasphorus rufus) across California. We expected distinct floral resource use based upon species’ migratory status (resident vs. migrant), sex, sampling period, and geographic region. We employed DNA metabarcoding to detect plant DNA in hummingbird fecal samples to analyze diet diversity, composition, overlap, and interaction networks. We found significant effects of sex, sampling period, and migratory status on the alpha and beta diversity of plant taxa present in fecal samples. Analyses of Anna's hummingbirds (Calypte anna) alone revealed that female fecal samples contained higher plant species richness. In addition to hummingbird-pollinated plants, fecal samples also contained non-ornithophilous plants and species of agricultural importance. Diet overlap and plant-pollinator network analyses revealed high overlap in plant taxa used between hummingbird species, and networks were more connected, less nested, and less specialized than null models. DNA metabarcoding is minimally invasive and provides a detailed view of hummingbird diet, permitting large-scale studies. Insights into hummingbird diets are especially valuable given the logistical difficulties of directly observing floral visitation and foraging across broad temporal and spatial scales.

蜂鸟（棘足动物科）是生物多样性热点地区的主要授粉媒介，包括北美的加州植物区系。关于蜂鸟饮食全年变化的信息知之甚少，特别是关于候鸟如何影响中途停留地的居民蜂鸟。在这项研究中，我们研究了蜂鸟的种类，迁徙状况，性别，地理区域和当地植物多样性如何在迁徙蜂鸟（主要是红褐色的蜂鸟，Selasphorus rufus）涌入之前，期间和之后影响花卉资源的使用。）在整个加利福尼亚州。我们根据物种的迁徙状况（居住或迁徙），性别，采样时间和地理区域，预计会有不同的花卉资源使用。我们采用DNA元条形码技术检测蜂鸟粪便样品中的植物DNA，以分析饮食的多样性，组成，重叠和相互作用网络。我们发现性别，采样时间和迁徙状况对粪便样品中存在的植物分类单元的α和β多样性具有重大影响。安娜的蜂鸟（Calypte anna）分析单独发现女性粪便样品含有较高的植物物种丰富度。除蜂鸟授粉的植物外，粪便样品还包含非嗜嗜性植物和具有农业重要性的物种。饮食重叠和植物传粉媒介网络分析显示，蜂鸟物种之间使用的植物分类群有高度重叠，并且网络比零模型更紧密，嵌套更少，更专业。DNA metabarcoding具有微创性，可提供蜂鸟饮食的详细视图，可进行大规模研究。鉴于直接观察花卉访问和在广泛的时空尺度上觅食的后勤困难，对蜂鸟饮食的见解特别有价值。