Garden Pollinators

In the summers of 2017-2019, we sampled Portland area gardens for pollinators. Bees collected in 2017 have been identified by Sarah Kornbluth. Bees collected in 2018 have been identified by Gabe Foote with assistance from Linc Best.

  • Butterflies
    • Cabbage white
    • Woodland Skipper
    • Grey Hairstreak
    • Western Tiger Swallowtail
    • California Tortoiseshell

You can learn more about our work, here.

  • Garden Selection:  Our goal was to sample 20-30 Portland area home and community gardens over three years.  We advertised our project at the Fall 2016 Metro Master Gardener re-certification, which was attended by ~250 Master Gardener volunteers.  At that event, 123 folks registered their interest in participating.  After circulating a follow-up survey, with more details about the study, 56 folks noted that they remained interested in participating in the study.  From these 56 potential study sites, I chose three transects with 31 potential study sites:
    • the Urban Core:  gardens located within Portland, in highly populated neighborhoods
    • the Forest Edge: gardens located within Portland, located adjacent to Forest Park
    • the Portland Suburbs:  gardens located outside of Portland, in a peri-urban landscape

We contacted these 31 potential study sites, and heard back from 25 people.  In April 2017, we visited each of these 25 potential study sites, to ensure that they are suitable sites for this study.  We ultimately settled on 24 study sites for our 2017 sample. In 2018, we scaled back to 22 sites, to make the study easier to manage.

  • Bee Sampling Methods:  we use a modification of the standardized method for monitoring bee populations, developed by LeBuhn, Griswold, McKinley, Droege, Roulston, Cane, Parker, Buchmann, Tepedino, Williams, Kremen and Messenger. Specifically, we use colored bowl traps to passively sample bees from home gardens. Following Fetridge et al. (2008), we focus our collections in flowerbeds, rather than lawns.  We place six water pan traps into each garden (two blue, two yellow and two white), and allow the traps to passively sample bees, for 24 hours.  We also hand collect bees, allocating 10 minutes of collection time within each garden. Across all gardens, and across the three years of this study, we will have allocated nearly 2,000 hours of hand-collecting time, and will have set 1,188 pan traps.