DOI: 10.5061/dryad.w9ghx3g08
title: Data from: Bee-mediated pollen transport across five urban landscape features: Buildings are important barriers

description: Urbanization alters insect pollinator diversity and foraging distances,
 while also providing novel pollinator habitats. Common landscape features
 that are characteristic of urban sprawl, such as roads and buildings, may
 alter the ability of insect pollinators to move and forage throughout the
 urban landscape. Given increased interest in urban pollinator
 conservation, more empirical information is needed about the spatial
 effects of cities on movement of pollinators and pollen. In this study, we
 aimed to quantify the effects of common urban landscape features on insect
 pollinator movement. We focused on roads, buildings, forest fragments,
 lawns, and community gardens. We studied 5 community garden sites, and the
 landscape features surrounding them, in Raleigh, North Carolina, USA. To
 measure pollinator movement across each feature, we placed clusters of
 potted cucumber plants on either side of a feature and added fluorescent
 dye powder to the stamens of the flowers. After 7 hours, we collected and
 counted the number of fluorescent dye powder grains transferred to each
 cucumber stigma. We conducted 10-minute visitation observations at each
 cluster to assess the pollinator community and to assess whether low
 visitation was linked to low dye transfer.  Buildings had the
 lowest estimated dye transfer, roads and gardens were intermediate, and
 lawns and forest fragments had the highest estimated dye transfer.
 Although plants associated with buildings also had low visitation rates,
 visitation overall was a poor predictor of dye transfer.  The
 most common visitors observed were Apis mellifera, Bombus spp., and
 Xylocopa virginica, indicating our results are likely primarily
 representative of these large, generalist bee species.  Our study
 highlights the heterogeneity of urban spaces to pollinators. We
 demonstrate which features facilitate and inhibit movements of
 pollinators, and thereby provide an empirical basis to map and assess
 functional landscape connectivity. This information can help cities
 identify and create connected networks of habitat for essential
 pollinators using geospatial methods, and can inform research about
 resource accessibility and foraging energetics for urban pollinators.
description: # Data from: Bee-mediated pollen transport across five urban landscape
 features: Buildings are important barriers Dataset DOI:
 [10.5061/dryad.w9ghx3g08](10.5061/dryad.w9ghx3g08) ## Description of the
 data and file structure In this study, we aimed to quantify the effects of
 common urban landscape features on insect pollinator movement. We focused
 on roads, buildings, forest fragments, lawns, and community gardens. We
 studied 5 community garden sites, and the landscape features surrounding
 them, in Raleigh, North Carolina, USA. To measure pollinator movement
 across each feature, we placed clusters of potted cucumber plants on
 either side of a feature and added fluorescent dye powder to the stamens
 of the flowers. After 7 hours, we collected and counted the number of
 fluorescent dye powder grains transferred to each cucumber stigma. We
 conducted 10-minute visitation observations at each cluster to assess the
 pollinator community and to assess whether low visitation was linked to
 low dye transfer. ### Files and variables #### File: dye\_counts.csv
 **Description:**  ##### Variables * Column 1: Number designation for each
 row that was created in R after data cleaning and download * Site: Name of
 site (sites 1 through 5). * Date: Date of sampling per site (YYYYMMDD). *
 barrier_crossed: Descriptor of what urban landscape feature an insect
 would have crossed to transfer dye onto a set of cucumber flowers.
 Categories are building, road, garden (community garden with culinary and
 ornamental plants), lawn (mowed turf, sometimes including small forbs),
 and forest (urban forest fragment). * color_rcvd: The dye color
 transferred onto each cucumber stigma by insects. Color categories are
 blue, green, orange, pink, salmon1, salmon3, white, yellow. * cluster:
 Categorical number designation according to each color added to cucumber
 flowers per site and date. All plants in a 'cluster' were placed
 together and were labeled by the researchers with the same color of dye.
 Cluster designations are nested within site and date. * group: Categorical
 number designation according to which landscape feature separated cucumber
 clusters per site and date. A group could include two or three clusters
 (see Fig. 1 in the main paper). Group designations are nested within site
 and date. * tube ID: Categorical ID number used to label and identify
 tubes of collected cucumber stigmas from 0 up. Each tube ID refers to a
 single stigma. Stigmas that received dye from more than one other cucumber
 group have multiple rows to represent the multiple colors of dye.   *
 grains dye: The number of grains of dye powder counted from each tube ID.
 #### File: dye\_probability\_vs\_insect\_visitation\_rate.csv
 **Description:** Data sheet that combines the estimated marginal means
 (emmeans) results from dye transfer (probability of dye transfer across a
 landscape feature and standard error) and insect visitation observations
 (rate of insect visitation to landscape feature-associated cucumbers and
 standard error). ##### Variables * feature: Urban landscape feature that
 was crossed by insects. Categories are building, road, garden (community
 garden with culinary and ornamental plants), lawn (mowed turf, sometimes
 including small forbs), and forest (urban forest fragment). * rate: Insect
 visitation rate to landscape feature-associated cucumbers (visits per 10
 min). * rate_se: SE (standard error) of insect visitation rates per
 feature. * prob: Fluorescent dye powder transfer probability per feature.
 * prob_se: SE (standard error) of dye powder transfer probability per
 feature. #### File: insect\_visitation.csv **Description:** Insect
 visitation observation counts per cucumber group, site, and date. Insects
 were identified on the wing to the taxonomic groups in columns 9:24
 (Bombus:Toxomerus). A visit was tallied each time an individual landed on
 a cucumber flower. ##### Variables * Site: Name of site (sites 1 through
 5). * Date: Date of sampling per site (YYYYMMDD). * round: Month of
 sampling- either June or July. * start time: Time at beginning of
 observation period (HH:MM); observations were 10 minutes each so each time
 period should be equal. * end time: Time at the end of observation period
 (HH:MM) * cluster: Number designation according to each color added to
 cucumber flowers per site and date. All plants in a 'cluster'
 were placed together and were labeled by the researchers with the same
 color of dye. Cluster designations are nested within site and date. * M
 flwr: The number of male flowers the observer could see from their
 observation spot. * F flwr: The number of female flowers the observer
 could see from their observation spot. * Bombus: Number of Bombus spp.
 visits that were not identified to species level. * B impatiens: Number of
 Bombus impatiens tallied. * B gris: Number of Bombus griseocollis tallied.
 * Apis: Number of Apis mellifera tallied. * Megachile: Number of Megachile
 tallied (not identified to species level). * Xylo. virginica: Number of
 Xylocopa virginica tallied. * Lasioglossum: Number of Lasioglossum tallied
 (not idenitified to species level). * Ceratina: Number of Ceratina tallied
 (not identified to species level). * Halictus: Number of Halictus tallied
 (not identified to species level). * Augo: Number of Augochlora/
 Augochlorella tallied (not identified to species level). * Skipper: Number
 of skippers (Hesperiidae) tallied (not identified to genus/species level).
 * fly: Number of flies (Diptera) tallied (not identifies to family level).
 * Polistes wasp: Number of Polistes wasps tallied (not identified to
 species level). * June bug: Number of green June bugs (Cotinis nitida)
 tallied. * yellow jacket: Number of yellow jackets (Vespula maculifrons)
 tallied. * Toxomerus: Number of hoverflies (Toxomerus spp.) tallied. ####
 File: insect\_visitation\_estimate.csv **Description:** This dataset is a
 subset of insect visitation observation counts, where each group is
 represented by the cluster with the smallest number of visits. This
 dataset was used to determine the conservative estimate of rate of insect
 visitation that would have limited dye transfer across associated urban
 landscape features, and was derived from the insect_visitation.csv
 dataset. As in that dataset, insects were identified on the wing to the
 taxonomic groups in columns 12:27 (Bombus:Toxomerus). A visit was tallied
 each time an individual landed on a cucumber flower. One row has NA values
 since the cucumber pots were stolen before we could do insect visitation
 observations. ##### Variables * Column 1: Number designation for each row
 that was created in R after data cleaning and download. * Site.x: Name of
 site (sites 1 through 5). * Date.x: Date of sampling per site (YYYYMMDD).
 * SiteDateBarrier: Housekeeping variable that creates a unique ID for each
 combination of site, date, and barrier crossed. * barrier: Where the
 cucumbers were located in relation to other cucumbers (i.e. if
 'barrier' lists two feature types, then this cluster of
 cucumbers was located in the middle of setup design B shown in Fig. 1 of
 the main paper; otherwise a single feature is listed). Barrier categories
 are building, road, garden (community garden with culinary and ornamental
 plants), lawn (mowed turf, sometimes including small forbs), and forest
 (urban forest fragment). * barrier_crossed: Descriptor of what urban
 landscape feature an insect would have crossed over to transfer dye of the
 specified 'color rcvd' onto a stigma. Categories are building,
 road, garden (community garden with culinary and ornamental plants), lawn
 (mowed turf, sometimes including small forbs), and forest (urban forest
 fragment). * color_rcvd: The dye color expected to be received from the
 cucumbers on the other side of the 'barrier crossed'. * type:
 Refers to role of a cucumber cluster in the study: donor = cucumbers are
 expected to transfer dye to cucumbers on other side of feature, recipient
 = cucumbers are expected to receive transferred dye from cucumbers on
 other side of feature, recipient/donor = cucumbers are expected to
 transfer and receive dye. * cluster: Categorical number designation
 according to each color added to cucumber flowers per site and date. All
 plants in a 'cluster' were placed together and were labeled by
 the researchers with the same color of dye. Cluster designations are
 nested within site and date. * group: Categorical number designation
 according to which landscape feature separated cucumber clusters per site
 and date. A group could include two or three clusters (see Fig. 1 in the
 main paper). Group designations are nested within site and date. *
 tot_flwr: Total of male and female flowers an observer could see from
 their observation spot. * Bombus: Number of Bombus spp. visits that were
 not identified to species level. * B impatiens: Number of Bombus impatiens
 tallied. * B gris: Number of Bombus griseocollis tallied. * Apis: Number
 of Apis melliferia tallied. * Megachile: Number of Megachile tallied (not
 identified to species level). * Xylo. virginica: Number of Xylocopa
 virginica tallied. * Lasioglossum: Number of Lasioglossum tallied (not
 identified to species level). * Ceratina: Number of Ceratina tallied (not
 identified to species level). * Halictus: Number of Halictus tallied (not
 identified to species level). * Augo: Number of Augochlora tallied (not
 identified to species level). * Skipper: Number of skippers (Hesperiidae)
 tallied (not identified to genus/species level). * fly: Number of flies
 (Diptera) tallied (not identifies to family level). * Polistes
 wasp: Number of Polistes wasps tallied (not identified to species level).
 * June bug: Number of June bugs (Cotinis nitida) tallied. * yellow
 jacket: Number of yellow jackets (Vespula maculifrons) tallied. *
 Toxomerus: Number of hoverflies (Toxomerus spp.) tallied. * total: Total
 insect observations.