Saha, K., & Balakrishnan, R. (in press). Ecological and behavioural determinants of sex-biased predation of katydid prey by a bat predator, Behavioral Ecology.

Dataset DOI: 10.5061/dryad.866t1g24s

Authors

Kasturi Saha^1*, Rohini Balakrishnan¹

^1. Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, Karnataka, India 560012

* Corresponding author

Kasturi Saha: kasturisahaks@gmail.com, http://orcid.org/0000-0002-7149-9035

Rohini Balakrishnan: brohini@iisc.ac.in, http://orcid.org/0000-0003-0935-3884

Date and Location where the data was collected

December 2018 – March 2020; Mala village, Udupi district, Karnataka, India (13°13’31’’, 75°05’25”)

Description of the data and file structure

This repository contains the data and the code supporting the analysis used in the investigation of ecological and behavioral factors driving sex-biased predation of the katydid prey genus Mecopoda by a bat predator Megaderma spasma. Mecopoda spp. males are consumed more than females in the breeding season, but females are consumed more in the non-breeding season. We compared this with the availability of the males and females across seasons in the wild, which indicated male-biased predation. Next, we compared the predation risk associated with their mate-finding behaviors in enclosure experiments and examined the prevalence of their risky behaviors using field observations. The results show that males perform high-risk behaviors, such as calling and flight, with a high prevalence. Although flight is equally risky for both sexes, females rarely fly.

Note: NA = data not available

Files and variables

File: prey_sex_ratio_(availability)_raw_data.csv

Description: sex ratio of prey katydids representing the availability of the male and female katydids in the wild, measured as the number of adult males and females recorded during field sampling.

Variables

• month: month in which prey katydid availability was sampled.
• week: week number of prey katydid availability sampling.
• date: date of prey katydid availability sampling in dd-mm-yyyy format.
• place: name of the locality or area where sampling was conducted.
• site: site ID.
• UTM_coordinate_east: easting value (in meters) indicating the site’s position in the longitude direction, measured east of the central meridian of the UTM zone 43N.
• UTM_coordinate_north: northing value (in meters) indicating the site’s position in the latitude direction, measured north of the equator in UTM Zone 43N.
• site_selection: whether the site selection was done manually or by random.
• male: number of katydid males found in that site.
• female: number of katydid females found in that site.

File: culled_prey_remain_(predation)_raw_data.csv

Description: culled prey remains collected from bat roosts indicating predation, measured by number of forewing remains of male and female katydids.

Variables

• month: month in which katydid culled remains were collected from bat roosts.
• week: week number corresponding to the collection of katydid culled remains.
• date: date of katydid culled remains collection in dd-mm-yy format.
• roost_name: bat roost ID.
• male_forewing: number of male culled remains i.e., forewings of male katydids found in the bat roost.
• female_forewing: number of female culled remains i.e., forewings of female katydids found in the bat roost.

File: prey_availability_and_predation_weekly_data.csv

Description: prey availability and predation data aggregated and organized on a weekly basis.

Variables

• season: season for the week; either breeding or non-breeding season of the katydid.
• week: week number within the season, breeding season comprised 16 weeks (with availability data missing on week 1), and nonbreeding season comprised 8 weeks.
• sites_availability: number of sites sampled for prey availability during that week.
• male_availability: total number of male katydids recorded across all sampled sites that week.
• female_availability : total number of female katydids recorded across all sampled sites that week.
• bat_roosts: number of bat roosts inspected for culled katydid wing remains (predation) during that week.
• male_predation: total number of male wing remains found in the bat roosts that week.
• female_predation: total number of female wing remains found in the bat roosts that week.

File: prey_availability_and_predation_monthly_data.csv

Description: prey availability and predation data aggregated and organized on a monthly basis.

Variables

• season: season for the month; either breeding or non-breeding season of the katydid.
• month: month of sampling.
• number_of_sites: number of sites sampled for prey availability during that month.
• male_availability: total number of male katydids recorded across all sampled sites that month.
• female_availability: total number of female katydids recorded across all sampled sites that month.
• total_availability: total number of katydids recorded across all sampled sites that month.
• number_of_roosts: number of bat roosts inspected for culled katydid wing remains (predation) during that month.
• male_predation: total number of male wing remains found in the bat roosts that month.
• female_predation: total number of female wing remains found in the bat roosts that month.
• total_predation: total number of katydid wing remains found in the bat roosts that month.

File: behavioral_experiment_data.csv

Description: dataset from a controlled bat-katydid enclosure experiment examining bat responses to katydid males and females engaged in mate-finding behavior (calling, walking, and flying).

Variables

• date: date of experiment in dd-mm-yyyy format.
• day: day number of experiment, with day 1 indicating the day after capturing the bat.
• time: time of experiment.
• bat_id: ID of the captured bat.
• prey_sex: sex of the prey katydid.
• treatment_category: the behavioral state of the katydid which were divided into three categories for ease of analysis i.e., (1) signalling, (2) searching by walk, and (3) searching by flight. 
• treatment: the sex-associated treatment applied within the three treatment categories mentioned above. signalling was a male-specific treatment, whereas searching by walk and searching by flight applied to both males and females, as well as female phonotaxis i.e., female walk/flight while the male call was being played from a speaker.
• bat_approach: bat response to the treatment in binary format, whether the bat flew towards the prey katydid.
• capture: bat response to the treatment in binary format, whether or not the bat successfully caught and fed on the prey.
• flight_duration_in_seconds: duration of prey katydid flight in seconds.
• inducing_prey_behaviour: indicates whether the prey behavior was self-induced or induced by the human observer by tapping with a stick of blowing wind through a pipe.

File: prevalance_of_risky_behavior_data.csv

Description: focal observation data of katydid individuals examining the prevalence of risky behaviors (call, flight) in the wild.

Variables

• date: date of focal behavioral sampling of prey katydids in dd-mm-yy format.
• sex: sex of the katydid.
• duration_of_observation_in_minutes: duration of focal observation of katydid behavior.
• flight: number of times the katydid took flight.
• call: number of times the (male) katydid called for more than 3 minutes.

File: katydid_analysis_script.R

Description: R script to reproduce the statistical analysis and figures.

Code/software

All analyses were carried out in the R Statistical Software (version 4.5.1; R Core Team 2025) using the packages lme4 (version 1.1.37), sjPlot (version 2.9.0), and ggplot2 (version 3.5.2). File "katydid_analysis_script.R" can be used to reproduce the statistical analysis and figures.