These data were collected by Carla J. Essenberg, who can be contacted with questions. Until July 2012, she will be at the University of California-Riverside. For three years thereafter, she will be at the University of Arizona. ##################################################################### FILE: Visitation.csv OVERVIEW: Per-flowerhead visitation rates to Holocarpha virgata ssp. virgata (Asteraceae) in 2.25 x 2.25 m plots that were thinned to different flowerhead densities DATA CONTAINED IN EACH COLUMN: Week: 1: 10-14 Aug. 2009; 2: 17-21 Aug. 2009; 3: 24-28 Aug. 2009; 4: 31 Aug. – 4 Sept. 2009 Date: yyyymmdd Plot: Each plot receives a unique designation; some plots were used multiple times on different days (usually for different flowerhead density treatments) N: number of ten-minute observations from which these average visitation rates were obtained Density: H. virgata flowerhead density after thinning, in flowerheads/m^2 Quality: Estimated average number of open disk florets per flowerhead HalVis: Per-flowerhead visitation to H. virgata by large sweat bees (Hymenoptera: Halictidae: Halictus ligatus, Lasioglossum titusi), in visits per flowerhead per hour TotVis: Per-flowerhead visitation to H. virgata by all taxa combined, in visits per flowerhead per hour ##################################################################### FILE: FlowerHandlingTimes.csv OVERVIEW: Flowerhead handling times of large sweat bees (H. ligatus and L. titusi) observed visiting H. virgata during the visitation observations recorded in Visitation.csv DATA CONTAINED IN EACH COLUMN: Week: same as in Visitation.csv Date: Same as in Visitation.csv Plot: Same as in Visitation.csv Density: Same as in Visitation.csv Bee: A unique number for each bee (some numbers are skipped) HT: Flowerhead handling time (each value is the duration of a single flowerhead visit), in seconds ##################################################################### FILE: FlightDurations.csv OVERVIEW: Durations of flights between H. virgata flowerheads by large sweat bees (H. ligatus and L. titusi) observed during the visitation observations recorded in Visitation.csv DATA CONTAINED IN EACH COLUMN: Week: same as in Visitation.csv Date: Same as in Visitation.csv Plot: Same as in Visitation.csv Density: Same as in Visitation.csv Bee: A unique number for each bee, which corresponds to the number for that bee in FlowerHandlingTimes.csv FT: Between-flowerhead flight duration (each value is the duration of a single flight), in seconds ##################################################################### FILE: TransectDensities.csv OVERVIEW: Weekly average densities of the flowerheads of H. virgata and flower visitors to H. virgata in six 1m x 30m transects located within the approximately 0.7-ha H. virgata patch containing the experimental plots referenced above. All flowerheads in each transect were counted once weekly. Insect densities were recorded during slow walks along the side of each transect three times per morning of the experiment, for a total of 15 times per week. These transect walks were randomly interspersed with the insect visitation observations described in Visitation.csv. DATA CONTAINED IN EACH COLUMN: Week: Same as in Visitation.csv Transect: The six transects are numbered “T3” through “T8” FlDen: Average density of H. virgata flowerheads, in flowerheads/m^2 HalDen: Average density of large sweat bees (H. ligatus and L. titusi), in bees/m^2 TotDen: Average density of all flower visitors combined, in insects/m^2 #####################################################################