Male bumblebees sustain mate-seeking by adjusting foraging to environmental conditions

GENERAL INFORMATION 1. Paper Citation Rossi, Natacha; Doussot, Charlotte; Woodgate, Joseph L.; Lihoreau, Mathieu; Chittka, Lars. Male bumblebees sustain mate-seeking by adjusting foraging to environmental conditions. Behavioral Ecology (in press) 2. Brief abstract Male bees navigate complex trade-offs between energy acquisition and reproductive signaling, yet their movement strategies remain understudied. Unlike workers that optimize foraging to support the colony, male bumblebees (Bombus terrestris) forage independently to collect nectar and deposit sex pheromones on selected plants. Using high-resolution 3D tracking in an indoor flight cage, we investigated how the spatial arrangement of nectar and scent-marking sites, along with nectar availability, influence male movement patterns. We manipulated the distribution of feeders (artificial flowers) and scent-marking locations (branches), and varied nectar delivery rates, to assess effects on foraging, scent-marking, and patrolling. Males responded strongly to spatial structure: in clumped arrays with evenly spaced resources, movements between consecutive visits were shorter and more localized, while in dispersed arrays with irregular spacing, transitions were longer and more variable. The combination of dispersed spacing and low nectar availability imposed the highest foraging demands, resulting in fewer feeding events and reduced total feeding time. Despite these increased costs, males maintained consistent investment in reproductive behaviors, suggesting a prioritization of mate-seeking over energy gain. Rather than reducing signaling, males adjusted their foraging strategy—favoring fewer but prolonged feeding bouts when nectar availability allowed. These findings reveal a unidirectional behavioral adjustment, in which foraging is modulated to sustain reproductive effort, and show how spatial resource structure and nectar availability together shape movement decisions in male pollinators. 3. Originators Rossi, Natacha 4. Contact information Rossi, NatachaEcology and Evolution, School of Life Sciences, University of Sussex, Brighton, [e-mail]; [e-mail] 5. Date of data collection June 2021 - July 2022 6. Geographic location(s) of data collection Queen Mary University of LondonMile End RoadLondon E1 4NS 7. Information about funding sources that supported the collection and curation of thedata This work was supported by a postdoctoral fellowship from the Fyssen Foundation 2020-2022 and EPSRC Program Grant (Brains on Board: Neuromorphic Control of Flying Robots, grant number: EP/P006094/1). CD and ML received support from the European Commission (ERC Bee-Move, grant number: 101002644). ACCESS INFORMATION 1. Licenses/restrictions placed on the data Creative Commons Attribution 4.0 International 2. Data derived from other sources DATA FILES AND VARIABLES 1. TrackData csv files These files contain raw 3D and 2D tracking data for male bumblebees. Each row represents a single time point (frame) in the tracking sequence. Three-dimensional coordinates and derived movement variables are expressed in calibrated real-world units (millimetres), while two-dimensional camera-based measurements are expressed in pixels. IDENTIFIERS AND METADATA - All3DInd: Row index for the combined 3D tracking dataset.- Camera1DataInd: Row index corresponding to Camera 1 tracking data.- Camera2DataInd: Row index corresponding to Camera 2 tracking data.- Index_TrackFileData: Index of the processed tracking file.- TrackFilePath_Processed: Original local path of the processed tracking file.- MaleID: Identifier assigned to the tracked male bumblebee.- ID_No: Numeric identifier for the tracked individual.- Log_Array_Name: Full description of the feeder/branch array configuration.- Array_Name: Short name of the array configuration.- Array_Code: Numeric code for the array configuration.- Pump_Configuration_Name: Description of the pump configuration.- Pump_Configuration_Code: Numeric code for the pump configuration.- MaleColony: Colony identity of the male (if available).- Size_mm: Body size of the male bumblebee, in millimetres (if available). TEMPORAL AND EXPERIMENTAL INFORMATION - Year: Year of recording.- Month: Month of recording.- Day: Day of recording.- Trial_3D: Trial number for the 3D tracking dataset.- Trial_C1: Trial number for Camera 1.- Trial_C2: Trial number for Camera 2.- Start_time_C1: Start date and time of Camera 1 recording.- Start_time_C2: Start date and time of Camera 2 recording.- Real_time_C1: Absolute clock time for Camera 1 observations.- Real_time_C2: Absolute clock time for Camera 2 observations.- Trial_time_C1: Elapsed trial time for Camera 1, in seconds.- Trial_time_C2: Elapsed trial time for Camera 2, in seconds.- Recording_time_C1: Elapsed recording time for Camera 1, in seconds.- Recording_time_C2: Elapsed recording time for Camera 2, in seconds.- Video_time_C1: Elapsed video time for Camera 1, in seconds.- Video_time_C2: Elapsed video time for Camera 2, in seconds.- time: Elapsed time from the start of the trial, in seconds. VIDEO AND FILE REFERENCES - Video_file_Camera1: Filename/path of Camera 1 video.- Video_file_Camera2: Filename/path of Camera 2 video.- TrackFilePath_3D: Path to the original 3D tracking file.- TrackFilePath_Camera1: Path to Camera 1 tracking file.- TrackFilePath_Camera2: Path to Camera 2 tracking file. TIME CODE VARIABLES - HMSN_C1_1–HMSN_C1_4: Hour, minute, second, and sub-second/frame index for Camera 1.- HMSN_C2_1–HMSN_C2_4: Hour, minute, second, and sub-second/frame index for Camera 2.- HMSN: Combined time code variable. POSITION AND TRACKING (3D) - x: 3D x-coordinate of the bee position, in millimetres (mm).- y: 3D y-coordinate of the bee position, in millimetres (mm).- z: 3D z-coordinate of the bee position, in millimetres (mm).- inters_err_: 3D reconstruction (intersection) error, in millimetres. TRACK STRUCTURE - block_: Tracking block identifier.- line_: Frame/line identifier within the tracking sequence.- plumeCode: Code indicating odour plume condition.- interp_code: Code indicating interpolation status of the tracking data point. PATH AND MOVEMENT METRICS - path3d: Cumulative 3D path length, in millimetres.- pathXy: Path length in the XY plane, in millimetres.- pathXz: Path length in the XZ plane, in millimetres.- tort_3d: Tortuosity of the 3D path.- tort_Xy: Tortuosity in the XY plane.- tort_Xz: Tortuosity in the XZ plane. VELOCITY AND SPEED - velocityX: Velocity along the x-axis, in mm/s.- velocityY: Velocity along the y-axis, in mm/s.- velocityZ: Velocity along the z-axis, in mm/s.- speed: 3D movement speed, in mm/s.- speedXy: Movement speed in the XY plane, in mm/s. DIRECTION AND ANGULAR VARIABLES - trackXv, trackXy, trackXz: Track/heading angles in different projection planes, in degrees.- courseXv, courseXy, courseXz: Course direction angles, in degrees.- driftXv, driftXy, driftXz: Drift angles relative to movement direction, in degrees.- ang_ch_Xv, ang_ch_Xy, ang_ch_Xz, ang_ch_3d: Angular change between successive steps, in degrees.- angVel_Xv, angVel_Xy, angVel_Xz, angVel_3d: Angular velocity, in degrees per second. SPATIAL ZONES - zoneXInd_: Zone index along the x-axis.- zoneYInd_: Zone index along the y-axis.- zoneZInd_: Zone index along the z-axis.- zoneCyl_: Cylindrical zone index. 2D CAMERA-BASED TRACKING VARIABLES (Camera-based measurements are in pixels) - X_center_C1, Y_center_C1: Centroid coordinates in Camera 1 (pixels).- Area_C1: Detected object area in Camera 1 (pixels²).- Areachange_C1: Change in detected area between frames (Camera 1).- Elongation_C1: Shape elongation metric (Camera 1).- Distance_moved_C1: Distance moved between frames (pixels).- Velocity_C1: Velocity in Camera 1 (pixels/s).- X_center_C2, Y_center_C2: Centroid coordinates in Camera 2 (pixels).- Area_C2: Detected object area in Camera 2 (pixels²).- Areachange_C2: Change in detected area between frames (Camera 2).- Elongation_C2: Shape elongation metric (Camera 2).- Distance_moved_C2: Distance moved between frames (pixels).- Velocity_C2: Velocity in Camera 2 (pixels/s). DISTANCE TO STRUCTURES - Dist_to_Closest_Location_XY: Distance to nearest mapped location in XY plane, in mm.- Dist_to_Closest_Location_3D: 3D distance to nearest mapped location, in mm.- Dist_to_Closest_Location_Z: Vertical distance to nearest mapped location, in mm. LOCATION INFORMATION - Closest_Location_Name_Full: Full name of nearest mapped location.- Closest_Location_Name: Short name of nearest mapped location.- Closest_Location_Code: Numeric code of location.- Closest_Location_Type: Type/category of location. BEHAVIOURAL VARIABLES - Movement_Name: Assigned movement category (e.g., flying).- Movement_Code: Numeric code for movement category.- Behaviour_Name: Behavioural classification.- Behaviour_Code: Numeric code for behaviour. TRACK SEGMENTATION - Segment_No: Segment number within the track.- Visit_No: Visit number to a mapped location.- Patrol_No: Patrol sequence number.- LandingVisit: Indicator of landing event (0 = no, 1 = yes). SOFTWARE AND ANALYSIS ENVIRONMENT All statistical analyses were conducted in R version 4.4.2 (R Core Team, 2024). The primary R packages used for analyses included: lme4 (Bates et al. 2015) emmeans (Lenth 2024) performance (Lüdecke et al. 2021) car (Fox and Weisberg 2019) glmmTMB (Brooks et al. 2017) Movement transition analyses, route simulations, and determinism calculations were conducted in Python version 3.11.7 using custom scripts. 3D tracking data were generated using EthoVision XT 16.0.1538 and Track3D (Noldus Information Technology, Wageningen, The Netherlands). 2. Video files The repository also contains representative raw video files used for tracking. These files correspond to the original recordings from which the tracking data were derived.