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Oregon Bee Atlas: native bee findings from 2018

Lincoln Best1*, Cody Feuerborn1, Jennifer Holt1, Sarah Kincaid1, Christopher J. Marshall2,  
Andony Melathopoulos1 , Samuel V.J. Robinson3 

* Corresponding author: Lincoln.Best@oregonstate.edu 
1 Department of Horticulture, Oregon State University, 4017 Agricultural and Life Science Building
     Corvallis, Oregon, USA 97331-7304
2 Department of Integrative Biology, Oregon State University 3029 Cordley Hall, Corvallis, Oregon, USA 97331-7304
3 Postdoctoral Associate, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada

Cite this work as: 

Best, L., C. Feuerborn, J. Holt, S. Kincaid, C.J. Marshall, A. Melathopolous and S.V.J. Robinson. 2021. Oregon Bee Atlas: 
native bee findings from 2018. Catalog of the Oregon State Arthropod Collection. 5 (1) 1— 12. 

  DOI: https://doi.org/10.5399/osu/cat_osac.5.1.4647.

Abstract

The Oregon Bee Atlas is a new volunteer-led effort to characterize the bee fauna of the state of Oregon 
by collecting, preparing, and databasing native bee species and capturing plant host records. In 2018, 
volunteers collected 11,044 bee specimens across 33 Oregon counties, representing 179 unique bee 
species, and 32 unique bee genera. Specimens were collected from a total of 310 unique flowering 
plant genera, resulting in one of the largest state-level databases of bee-host plant interactions. 
Volunteers produced valuable occurrence records for species poorly known for the State, and species 
of conservation concern. The 2018 efforts constitute a proof-of-concept of a specimen-focused 
volunteer native bee survey.

Introduction

The Oregon Bee Atlas (OBA) is a volunteer-focused initiative to survey the bee fauna of Oregon.  The 
mission of the OBA is to train and equip citizen scientists to: (a) create and maintain a comprehensive, 
high quality and publicly accessible inventory of the state’s native bees and their plant-host 
preferences, (b) to educate Oregonians on the state’s bee biodiversity, and (c) to conduct an on-going 
survey of native bee populations in order to assess their health. Started in 2018 by Oregon State 
University (OSU), Oregon Department of Agriculture (ODA), and Oregon Department of Forestry 
(ODF), the OBA was established as a response to the general lack of knowledge about the status of 
Oregon’s native bees. 

The state of Oregon, located in the Pacific Northwest (PNW) of the United States, presents unique 
challenges for detecting changes in native bee populations. These challenges stem from the fact 
that the State contains 12 distinct ecoregions (Level III, Environmental Protection Agency) that are 
dissected by two broad mountain ranges, resulting in distinct pollinator communities.  Although a 
number of outstanding hymenopterists and pollination biologists have worked on PNW bees, their 
efforts were primarily based on particular groups of interest and/or specific crops.  A general interest 
in native pollinators and their role in agriculture and ecology in more recent years has kindled an 
interest and need to examine the regional bee fauna as a whole. Early faunistic work on Western 
North American bees centered more heavily on California and other Southwestern states (see: 
Michener 1979, p. 238). While Moldenke (1976) compared the bee fauna of Pacific North America 



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to that of Chile, that work lacks a comprehensive list of species and any means to identify them.  
Since the 1980’s Oregon has lagged behind other parts of the US in terms of sampling efforts, with 
only limited and restricted studies having taken place, many of which were focused primarily on 
managed lands and/or specific crops (Stephen et al. 2009; Broussard et al. 2011; Kimoto et al. 2012; 
Gonzalez et al. 2013; McIver and Erickson 2012; Mciver et al. 2009; Roof et al. 2018; Tubbesing et al. 
2014). Publicly available records on the Global Biodiversity Information Facility show 34% more bee 
species occurrence records generated east of the 100th Meridian than west of it since 1980. (GBIF.org 
2020). With a few exceptions (e.g., bumblebees), the PNW, and Oregon in particular, lack synoptic 
identification tools or even a solid authoritative checklist for its regional bees. As a result, it can be 
difficult, if not impossible, to reliably identify even some common taxa. 

The OBA came about as a direct response to this problem, providing a unique, cost effective pathway 
to generate museum-quality bee specimens from areas that have historically been poorly sampled. 
Unlike similar programs in the United States, the OBA uses a largely volunteer workforce to collect 
and prepare specimens, and to provide entry level taxonomic support. Through the framework 
of the OBA, volunteers receive the necessary training to complete these tasks, and are partnered 
with taxonomists and database managers to ensure quality records are created and maintained. All 
observational records generated by the OBA are based on identified specimens. Exemplar specimens 
are deposited in the Oregon State Arthropod Collection (OSAC) to facilitate identification into the 
future, and so they can be used as comparative reference material.  All records are made publicly 
available.

In addition to generating quality specimens and vouchered observational records, the OBA places a 
strong emphasis on community engagement and education. On an annual basis, each OBA member is 
required to attend at least one regional outreach event per year, with many attending multiple events. 
This allows OBA members to share project findings and provide information on Oregon bees and the 
problems they face with the general public. 

Here, we present the findings from the first year of the Oregon Bee Atlas (2018), reviewing the spatial 
distribution of sampling, the species detected, and notable native bee discoveries.  

Methods

Volunteers 

Volunteer recruitment for the OBA has largely drawn from pre-existing groups, such as OSU Master 
Gardeners, Master Naturalists, and local beekeepers. Efforts were made to advertise training events 
to these audiences and the general public through Extension partnerships, outreach events, social 
media, and newspaper articles.  Volunteer applicants were placed in teams based on proximity to 
training locations. Six Oregon events, which trained a total of 153 students, were held in the cities of 
Klamath Falls, Pheonix, Grants Pass, Canby, Corvallis, Bend, and Hood River. Trainings took place 
between June 2017 and February 2018, and in most instances training events lasted one full day. Top-
ics covered included:  project background, bee biology, insect collection, specimen preparation, and 
data entry. Two additional five-day courses were held on July 9-13 and 16-20, 2018 that covered ge-
nus-level identification of native bees in Oregon, and species-level identification of bumble bees.   



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Sampling methods and effort  

Two types of sampling were utilized by volunteers: (1) undirected, free sampling, and (2) directed 
sampling. For undirected sampling, volunteers were encouraged to collect bees often and wherever 
they chose, either independently or as a team.  In directed sampling, volunteer teams were asked to 
target two types of sites, one with a high level of native flowering plant species, and a second site 
that was highly managed or disturbed, such as an intensive agricultural or highly urbanized location. 
Teams were encouraged to visit each site roughly every two weeks to observe seasonal variability 
within bee communities.  Bees were primarily collected using a variable transect aerial netting, with a 
small subset collected using blue vane traps (see Westphal et al. 2008 for description of each method). 
Volunteers employing aerial netting were encouraged to collect bees from the same host plants into 
separate killing jars, in order to associate the bees with the host plant. In all cases, however, all sam-
pling conducted within a 1 ha radius of where sampling started was pooled together into a common 
sample (e.g., aerial netting from a given plant host species growing within a 1 ha area were pooled). 
All bees caught from a collector within this 1 ha unit, at a given date and time, and where applicable, 
from a given plant, were provided with a unique identifying number (Sample ID).  

Observational data entry, specimen preparation, and labeling 

Volunteers recorded the following core data: (a) full name of collector, (b) a Sample ID identifier, (c) 
the date and time when sampling was initiated, (d) the name of the closest geographic or civic land-
mark to the sampling area, (e) latitude and longitude coordinates in degree decimal format, and (f) 
the number of bees collected. For volunteers installing passive traps, the date and time that traps 
were removed was also included. When netting was conducted from a specific host plant, the family, 
genus, and species of the host plant was recorded.   

Volunteer data were recorded using two methods based on volunteer preference. A small number 
of volunteers used a hand-written field notebook. The majority of OBA volunteers, however, used 
a mobile phone in conjunction with the software package iNaturalist (www.iNaturalist.org). These 
volunteers were instructed to photograph and geotag an example of each plant host species that they 
sampled from, within a given collection area. The image was associated with the iNaturalist Project 
(Oregon Bee Project Regional Teams), allowing additional core data fields to be filled out by volun-
teers. Volunteers then returned home and pinned their specimens, ensuring that each specimen had 
a temporary label with the sample identification number (Sample ID). Specimen information was 
either: (a) extracted from the iNaturalist Project and reconfigured to a spreasheet using a Python com-
puter script, (b) input by volunteers or, in a limited number of cases, (c) manually input by Oregon 
Bee Atlas staff. All data were compiled in a single spreadsheet by Oregon Bee Atlas staff at Oregon 
State University, who also checked each data line for errors, and contacted volunteers for clarification 
when incorrect or ambiguous data were discovered. Records that lacked core data fields (collector 
name, time and date of collection, location information) were deleted from the final dataset.  
To ensure standardized and archival labels were placed on all specimens, the final labels were gener-
ated at Oregon State University on acid free cardstock paper, and then sent to volunteers to place on 
specimens. Label information was pulled from the verified and corrected database using a Microsoft 
Word Mail Merge template and then fed into templates that printed labels on 8.5” x 11” cardstock.  
These labels were then sent back to volunteers, who were able to place them on the appropriate spec-
imens via their unique field notebook number ([collector name] 18.[SampleID number].[specimen-
number]; e.g., LincolnBest18.21.3), which was included on the label itself.   



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Once specimens were labelled, volunteers worked to provisionally identify and sort their material. 
They were encouraged to bring material to the Oregon Bee Atlas for monthly open microscope ses-
sions (September-December, 2018) at Oregon State University for assistance with genus-level identifi-
cation.  Volunteers were instructed to turn their collections into Oregon State University by December 
21, 2018 for authoritative specimen identification and voucher selection. 

Specimen determinations were made by one of the authors (Lincoln Best), an experienced taxonomist 
with the western North American bee fauna.  Individual volunteer collections were graded by Best, 
based on accuracy of the identification (where applicable), organization, and the skill of specimen 
preparation. Every volunteer who submitted a collection received an individual evaluation grading 
sheet.  Voucher material that covered both the taxonomic and geographic breadth of the sampling 
was accessioned into the Oregon State Arthropod Collection, and excess material was then used to 
populate species-level reference collections of regional relevance for the volunteer teams. 

Data and metadata 

Once the annual data were collated into a single table, the data and metadata were checked for typo-
graphical errors and formatted to conform, wherever possible, to basic darwinCore biodiversity data 
standards (https://dwc.tdwg.org/).  The dataset will be made publically available via the OSAC IPT 
server (https://osac.oregonstate.edu/IPT) as well as provided as a .csv text file available as a down-
load (Supplement 1).

The final dataset contains 35 fields: 

occurenceID: this represents a unique identification number for observational records. OccurrenceID 
is cast differently when specimens are retained.  For occurrence records based on specimens housed 
in the collection, the occurrenceID is given the prefix: http://osac.oregonstate.edu/ followed by ‘SP/
OSAC_’ followed by the 10 digit museum-issued catalog number for the voucher specimens. For 
example: http://osac.oregonstate.edu/SP/OSAC_1234567890. These URL’s serve as a hyperlink to 
access the museum specimen record.  Observations for which the basisofRecord are not retained, 
are issued a URL with the same prefix, however, the “SP/OSAC_XXXXXXXXXXX” is replaced with 
“OBS/ OBA_”+ [collectorname]+ “:” + [OBAfieldnumber].  These URLs will also retrieve the obser-
vation record, but are not tied into the museum’s specimen-based inventory. An example includes: 
http://osac.oregonstate.edu/OBS/OBA_Stephanie_Hazen:18.035.057. 

catalogNumber: a unique catalog number given to a vouchered specimen for an observation depos-
ited into the OSAC, which is presented on a printed label in both arabic human readable digits and a 
datamatrix barcode.  As with the occurrenceID, the catalogNumber is represented in the datamatrix 
as the URL http://osac.oregonstate.edu/SP/OSAC_XXXXXXXXXX, where the X’s correspond to a 
unique 10-digit number.   

disposition: Whereas all observational records were based on physical specimens examined by a tax-
onomist (Lincoln Best), not all specimens were retained.  Observations for which a voucher specimen 
was not retained (e.g., accessioned into the museum) the catalogNumber is necessarily left blank and 
the disposition field indicates ‘not-retained’ as apposed to ‘confirmedPresent’. 

datasetName: The dataset name “OBA_OSAC_2018” is recorded in each record, in the event that 
these records are combined with other observational datasets. 



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basisOfRecord: all observational records in the OBA dataset are based on actual pinned specimens, 
although as noted, not all specimens were archived. 

fieldNumber: This number string corresponds to the Oregon Bee Atlas information recorded during 
the initial collecting and specimen submission process.  It is important to record in case a record’s 
history needs to be examined to verify and/or modify a record. 

bibliographicCitation: Each record in the dataset is provisioned with the full bibliographic citation for 
the dataset, enabling downstream users to cite the record explicitly.  Doing so provides an easy means 
to access the source of the data record and attribute proper credit to the creators of those records. 

license: these data are released under a creative commons license that makes them useable for 
non-commercial purposes with proper and appropriate attribution (eg., cited using bilbiographic-
Citation above. Details on the license can be found at: http://creativecommons.org/licenses/by-nc-
sa/3.0/ 

institutionCode: OSAC 

ownerInstitutionCode: OSAC 

rightsHolder: Oregon State University 

Collecting Date: The collecting date is stored in two forms and three separate parsed fields: day (1-
31), month (1-12), year (2018); and an eventDate text string, is included if possible for ease of using a 
date format where that is desirable. 

 locality data: locality data is stored in 6 fields: country, state, county, location, decimalLatitude, and 
decimalLongitude.  Georeferencing was provided by the collector and was either recorded in the field 
during the collecting event or determined subsequently based on maps and field notes. In all cases, 
they are recorded in decimal degrees with an accuracy of 3 decimal places (approximately +/- 100m). 

samplingProtocol: the collecting method is typically aerial net, where other means were used: eg., 
sweep net or pan trap, these were indicated. 

associated plant information: any bees collected in direct association with known plants has this 
information recorded in one of two ways.  If a bee, or bees, were collected directly from a plant while 
foraging, this is placed into the “associatedTaxa” field, using standard language recommended by 
DarwinCore, in which the type of relationship is stated followed by a colon and then the plant taxon, 
eg., “foraging on” : “Ericameria nauseosa”.  In cases where a sweep net or pan trap or bees were netted 
in the vicinity of known plants (e.g., bees were not directly observed visiting floral resources on these 
plants), this is placed in fieldNotes. 

recordedBy: provides the collector’s name 

phylum, class, order, family, subfamily, tribe, genus, species, and scientificName; all names were 
crosschecked against GBIF’s species name tool prior to being uploaded.  The full binomial with au-
thority and date of publication is provided in scientificName.   



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rank: lowest taxonomic rank the record is identified to. Sex and caste are recorded if known. 
repository: The repository is considered OSAC if voucher material was deposited in the museum.  
For observations for which the voucher was not retained, this field is left blank. 

identifiedBy and dateIdentified: determination information is provided in the identifiedBy and 
dateIdentified fields. In all but a few cases, the final 2018 dataset records were determined by Lincoln 
R. Best. 

Results

Volunteers

A total of 52 volunteers submitted collections of bees. Of the 52 volunteers, approximately 60% sub-
mitted collections over 50 bees, 11% submitted collections of more than 500 bees, and two volunteers 
submitted collections containing over 1,200 bees (Figure 1). Volunteers were largely based in counties 
directly west or east of the Cascade Mountains, with no collectors based in counties in Eastern Ore-
gon (Figure 2). 

Figure 1. The number of bee specimens submitted per volunteer collector in 2018. Reference lines 
indicate 50 and 500 bee specimen levels.



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Spatial distribution of sampling

Native bee specimens were collected from 34 of the 36 Oregon counties (Figure 3). Although 
specimen collection was spatially uneven across the State, 98.94% of specimens were collected outside 
of the Portland Metro area where most of our collectors live. Moreover, 36% of specimens were 
collected east of the Cascade Mountain range. 

Description of the native bee data

Volunteers collected 11,044 bees across 33 counties from March 15, 2017 to August 19, 2019. Bees were 
predominantly collected from three bee families, Apidae, Halictidae, and Megachilidae (Figure 4).  In 
total, volunteers collected bees from 43 genera, with the most commonly encountered genera baased 
on specimens being Halictus Latreille (1,906 specimens), Bombus Latreille (1,477 specimens), Osmia 
Panzer (1,092 specimens), Andrena Fabricius (991 specimens), and Ceratina Latreille (957 specimens). 
There are 179 species listed in the dataset although many specimens from a number of species-rich 
genera (e.g., Andrena Fabricius, Melissodes Latreille and Lasioglossum Curtis) were only determined to 
the generic level at the time of publication. We estimate that, once these are identified, the 2018 sur-
veys may ultimately yield examples of over 400 species.

Figure 2. Distribution of where volunteers who submitted collections of more than 50 bee specimens 
were based in 2018. The color of each county indicates the number of volunteers based in the county.



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Notable native bee discoveries

This state-wide survey effort produced valuable occurrence records for species poorly known for the 
region and for  species of conservation concern. Among the Halictidae, Agapostemon melliventris Cres-
son was recorded from the Alvord Desert, and Halictus virgatellus Cockerell from the alpine in the 
Wallowa Mountains. Among the Megachilidae, Ashmeadiella (Arogochila) foxiella Michener, Ashmeadiel-
la (Arogochila) timberlakei Michener, and Ashmeadiella (Ashmeadiella) foveata Michener were recorded 
from the high desert, with A. foveata being a novel state species record. The sand dune specialist 
Anthidium palliventre Cresson, was recorded from Newport, Oregon, and the rare Hoplitis (Proteriades) 
plagiostoma Michener was collected on Steens Mountain. In the alpine lava fields of McKenzie Pass, 
topotype specimens of Atoposmia oregona (Michener) were collected from its floral host Penstemon 
davidsonii Greene for the first time in Oregon in more than 50 years. Similarly, new occurrence records 
for Trachusa timberlakei (Schwarz) from the Cascade Range represent the second detection in more 
than 80 years in Oregon. Two infrequently detected species, Megachile mellitarsis Cresson, and Hoplitis 
louisae (Cockerell) were recorded from several localities east of the Cascades. The apid genus Pepona-
pis (Say) now relegated to subgeneric status in Eucera Scopoli, was documented for the first time in 
Oregon in 2018 (Best et al. 2019). Twenty-one species of bumble bees (Apidae: Bombus Latreille) were 
recorded including the species of conservation concern Bombus caliginosus (Frison), Bombus fervidus 

Figure 3. Heat map of 2018 volunteer sampling effort. Each dot represents a distinct sample event, 
which is a distinct collection within a specific bounded 1 ha area on a given date and time. The 
coloring of the county indicates the total number of specimens collected in the county.



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Figure 4. Number of specimens collected in 2018 by species, genus and family. 

Megachilidae

Halictidae
Colletidae

Apidae

Andrenidae

Anthidium atripes
Anthidium formosum
Anthidium palliventre

Anthidium placitum
Ashmeadiella cactorum

Ashmeadiella foveata
Ashmeadiella foxiella
Chelostoma minutum

Coelioxys alternata
Coelioxys edita

Dianthidium plenum
Dianthidium pudicum
Hoplitis plagiostoma

Megachile gentilis
Megachile inermis

Megachile mendica
Megachile subnigra

Megachile texana
Osmia juxta

Osmia marginipennis
Osmia rostrata
Osmia tanneri
Osmia tarsata

Anthidium tenuiflorae
Ashmeadiella timberlakei

Atoposmia abjecta
Atoposmia oregona
Dianthidium parvum

Megachile frigida
Osmia cara

Osmia longula
Osmia phaceliae
Osmia vandykei

Trachusa timerlakei
Anthidium emarginatum

Anthidium illustre
Ashmeadiella californica
Atoposmia copelandica

Dianthidium dubium
Hoplitis grinnelli
Hoplitis louisae

Megachile lippiae
Osmia gabrielis
Osmia inurbana

Osmia malina
Stelis montana

Chelostoma phaceliae
Hoplitis sambuci

Megachile coquilletti
Osmia visenda

Megachile mellitarsis
Megachile onobrychidis

Osmia exigua
Osmia regulina

Anthidium atrifons
Ashmeadiella cubiceps

Ashmeadiella difugita
Megachile melanophaea

Osmia enixa
Megachile addenda

Megachile montivaga
Osmia aglaia

Anthidium banningense
Anthidium mormonum

Heriades cressoni
Osmia integra
Osmia pusilla

Ashmeadiella bucconis
Megachile parallela

Megachile relativa
Osmia melanopleura

Megachile brevis
Osmia ribifloris

Anthidiellum notatum
Megachile wheeleri

Megachile centuncularis
Osmia cyanella
Stelis laticincta

Osmia nigrifrons
Hoplitis hypocrita
Megachile fidelis

Megachile apicalis
Osmia bruneri

Osmia atrocyanea
Anthidium utahense

Hoplitis producta
Osmia coloradensis
Megachile pugnata

Dianthidium subparvum
Hoplitis albifrons

Osmia californica
Osmia sericea

Dianthidium ulkei
Osmia calla

Osmia kincaidii
Osmia montana

Osmia brevis
Osmia lignaria
Hoplitis fulgida

Osmia densa
Megachile nevadensis
Megachile angelarum
Anthidium manicatum

Megachile perihirta
Protosmia rubifloris

Megachile rotundata
Osmia nemoris

Dufourea trochantera
Halictus virgatellus

Agapostemon melliventris
Lasioglossum zonulum
Lasioglossum sisymbrii

Agapostemon femoratus
Halictus confusus

Lasioglossum titusi
Agapostemon texanus

Halictus rubicundus
Agapostemon virescens

Halictus farinosus
Halictus ligatus

Halictus tripartitus
Colletes coloradensis

Anthophora californica
Bombus vagans

Ceratina neomexicana
Eucera acerba

Melecta pacifica
Xylocopa californica
Zacosmia maculata

Anthophora edwardsii
Bombus sitkensis
Bombus sylvicola
Melecta separata

Neopasites fulviventris
Anthophora ursina

Bombus occidentalis
Eucera lunata

Melecta thoracica
Anthophora pacifica

Diadasia diminuta
Eucera actuosa

Anthophora bomboides
Anthophora porterae

Bombus insularis
Ceratina sequoiae

Ceratina pacifica
Bombus flavidus

Ceratina tejonensis
Diadasia nigrifrons

Xylocopa tabaniformis
Bombus appositus

Anthophora terminalis
Bombus rufocinctus

Eucera cordleyi
Bombus nevadensis

Xeromelecta californica
Bombus morrisoni
Eucera edwardsii

Ceratina nanula
Bombus vandykei

Bombus griseocollis
Bombus huntii

Ceratina micheneri
Bombus melanopygus

Bombus flavifrons
Bombus caliginosus

Bombus centralis
Bombus fervidus

Apis mellifera
Bombus bifarius
Bombus mixtus

Anthophora urbana
Bombus vosnesenskii

Ceratina acantha
Andrena cyanella

Andrena rubicundus
Andrena transnigra
Calliopsis anthidia

Calliopsis edwardsii
Andrena prunorum

0 200 400 600 800
Number of specimens

Species

Megachilidae

Halictidae
Colletidae

Apidae

Andrenidae

Dioxys
Trachusa

Atoposmia
Chelostoma
Anthidiellum

Stelis
Coelioxys

Ashmeadiella
Dianthidium

Protosmia
Heriades

Hoplitis
Anthidium
Megachile

Osmia
Dufourea

Sphecodes
Agapostemon
Lasioglossum

Halictus
Hylaeus
Colletes

Zacosmia
Epeolus

Neopasites
Melecta

Xylocopa
Habropoda

Diadasia
Xeromelecta

Triepeolus
Eucera

Apis
Nomada

Anthophora
Melissodes

Ceratina
Bombus

Calliopsis
Perdita

Panurginus
Andrena

0 500 1000 1500 2000
Number of specimens

Genera

Megachilidae

Halictidae

Colletidae

Apidae

Andrenidae

0 1000 2000 3000
Number of specimens

Families



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(Fabricius), Bombus morrisoni Cresson, Bombus occidentalis Greene, Bombus sylvicola Kirby, and Bombus 
vandykei (Frison). Bombus vagans Smith, a species uncommonly detected in Oregon was found with-
in its known range in Wallowa County. Additional notable species records within the family Apidae 
were produced for Ceratina micheneri Daly, Ceratina neomexicana Cockerell, Ceratina sequoiae Michener, 
Ceratina tejonensis Cresson, Neopasites fulviventris (Cresson), and Zacosmia maculata (Cresson).

Description of host plant data

A total of 8,812 bee specimens were associated with a plant host (Supplement 2). The highest number 
of specimens were collected from Ericameria spp. (5% of plant records), followed by Rubus spp. (3% of 
plant records) and Phacelia spp. (2% of plant records). Survey across plant genera varied considerably 
among counties (Figure 5). The plant genera from which the most bee species were collected were 
Phacelia, Rubus, and Penstemon, hosting 50, 47, and 43 unique bee species respectively.

Discussion

The first year of the Oregon Bee Atlas has demonstrated the potential of trained volunteers to provide 
high quality bee biodiversity data. Unlike many other volunteer-based biodiversity surveys (van der 
Wal et al. 2015; Dickinson et al. 2010), Atlas volunteers surveyed far beyond urban areas, sampling 
extensively in the sparsely populated area east of the Cascade Mountains, and locating rare species of 
native bees. Also, unlike most other volunteer native bee surveys where volunteers collect bee pho-
to-vouchers (MacPhail, Gibson, Hatfield, et al. 2020; MacPhail, Gibson and Colla 2020; Falk et al. 2019; 

JosephineCurry Jackson

Coos

Klamath

Lake

Douglas
Harney

Lane Deschutes

Malheur

Crook

Benton
Linn

Jefferson
Grant

Lincoln
Wheeler

Polk
Baker

Marion

Yamhill Clackamas Wasco

Hood
RiverMultnomah Sherman

Washington

Tillamook Gilliam
Union

Morrow
WallowaUmatilla

ColumbiaClatsop

Plant Genera
≤3
≤15
≤37
≤73
≤105

Figure 5. The number of plant genera associated with bees records in 2018, by county.  



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Richardson et al. 2019), the OBA has demonstrated the feasibility of volunteers to do more technical-
ly demanding tasks, such as collecting, preparing, and databasing specimens. Moreover, volunteers 
have largely collected the specimens using active survey techniques, avoiding many of the processing 
costs and survey biases associated with programs that rely on passive trapping of bees (Portman et 
al. 2020). Finally, using an innovative workflow connected to iNaturalist plant photo-vouchers, the 
OBA has started to build the most comprehensive bee-host plant databases of any State in the United 
States. 
The initial results, which are biased in taxonomic identification effort towards the genus Bombus and 
the family Megachilidae, have provided new spatio-temporal data for many of the known species 
of the state fauna and have detected new state records. There are estimated more than 225 species 
among specimens not determined beyond the generic level, and this suggests that more than 400 
species were collected throughout the state by Oregon Bee Atlas Participants in 2018. By refining 
floral targets and habitats, we predict that future surveys are likely to detect more than 600 species in 
55 genera, including new state species, new generic records, and new data for species of conservation 
concern. 

The Oregon Bee Atlas will continue to develop and refine its training programs to prepare volunteers 
to conduct more targeted surveys associated with unique plant communities in Oregon, and plans 
to use historical records to guide volunteers. The Atlas’s short-term goal will be to develop a com-
prehensive checklist of Oregon native bees, including range maps. We anticipate that as our knowl-
edge of the occurrence and distribution of native bee species increases in step with a trained cadre of 
volunteers, Oregon will be well positioned to join national efforts to track the long-term population 
trends of US bee communities.

Acknowledgement 

The Oregon Bee Atlas would not be possible without the hard work and dedication of its volunteers 
(see Supplement 3 for a listing of volunteers who contributed to this dataset). We are particularly 
grateful the Oregon Bee Atlas Advisory Committee in 2018; Tom and Julie Biddle, Judi Maxwell, 
Michael O’Loughlin, Jerry Paul, Pete and Gretchen Peterson, Nicole Sanchez and Bonnie Shoffner. We 
are grateful to the Foundation for Food and Agriculture Research Pollinator Health Fund and Oregon 
Department of Agriculture for supporting the Oregon Bee Atlas. 

 
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