Data for "Hierarchical drivers operating across spatial and temporal scales shape activity in a threatened passerine bird"

Abstract This data set has been collected to test the effects of livestock grazing legacies and contemporary kangaroo grazing on the threatened Thick-billed Grasswren (TBGW) Amytornis modestus on an arid conservation reserve. Livestock grazing legacy effects were assessed by measuring proportional chenopod shrub cover, proportional understory vegetation cover, and TBGW activity using song meters along a distance from decommissioned artificial water points (AWP) gradient in four seperate paddocks in Spring 2024. Monitoring sites began at 100m from the AWPs and then occured at 1km intervals. Sites extened to 4km in one paddock and 5km in the remaining three paddocks. All sites with vegetation measurements were included in analysis of chenopod shrub and understory response to distance from AWP. Because TBGW activity was analysed in response to chenopod and understory cover, all sites were included in the TBGW model expect for 3000m in Leapyear paddock and 5000m in Cadnawatina where sd cards were corrupted. Contemporary kangaroo grazing impacts were investigated using three experimental 16 hectare kangaroo exclusion plots and three associated control plots. Proportional chenopod shrub and understory cover were measured in each plot in March, June, and November 2025. TBGW activity was monitored using camera traps. Data was analysed by modelling the respective responses of chenopod shrubs, understory vegetation, and TBGWs to kangaroo exlcusion. To determine whether grazing may reduced TBGW food activity, DNA metabarcording was conducted on TBGW scats that were collected within the kanagroo exclusion and control plots in June and November 2025. Plant genera and invertebrate families were identified by DNA that was detected within 67 TBGW scats. The total number of scats that each family/genera was detected in was calculted and presented as a histogram. Methods We conducted this study at Witchelina Nature Reserve (-30.02, 138.04). Landscape scale - We measured vegetation cover and TBGW activity in four independent paddocks at Witchelina in the Spring (September – November) of 2024. Vegetation cover was measured at each monitoring site using four 100m long step-point transects that intersected the middle point of each monitoring site, giving a total of roughly 400 intercepts per site. Vegetation present at each intercept was classified as chenopod shrub, understory vegetation (perennial grasses or ephemeral grasses, forbs, and non-woody subshrubs), or other. Approximately 400 step-points were recorded at each monitoring site. The proportional chenopod shrub cover and proportional understory vegetation cover was calculated by diving the number of intercepts either vegetation type was recorded by the total number of intercepts at each site. We deployed a Song Meter Micro at each monitoring site with the manufacturers (Wildlife Acoustics) default settings to record bird song daily for 1-hour before and after sunrise and sunset. Each song meter operated for between 54 to 59 days except for the unit at 3000m from AWP within “Leapyear” and 5000m in “Cadnawatina” (Figure 3) where SD cards were corrupted. Recordings were analysed using a custom classifier we developed using BirdNet v2.4’s adaptive modelling capabilities that can idenitify TBGW calls and assign confidence scores between 0 (low confidence) – 1 (high confidence. We manually validated 200 rndom TBGW calls by scoring a 0 for false positives and a 1 for true positives. Binomial regression where validation ~ confidence score was performed to calculate the confidence score above which there was 0.95 probability any identified call was correctly classified as a TBGW, with calls assigned a confidence score equal to or above this confidence score included in our analysis. Patch scale drivers of Thick-billed Grasswrens To assess the impact of kangaroo grazing on TBGW activity we measured Chenopod shrub cover, understory vegetation cover, and TBGW activity inside three 400 m x 400 m kangaroo grazing exclusion and associated control plots in the Autumn, Winter, and Spring of 2025. In each season, chenopod cover and understory vegetation cover were randomly sampled within each plot using the same step-point method as our landscape scale experiment, with five 600m transects and a total of approximate 600 step-points being completed within each replicate during each sample period. Proportional chenopod cover and proportional understory vegetation cover were calculated by dividing number of intercepts that each vegetation type was recorded by the total number of intercepts per sample. We monitored TBGW activity from the 1st of March 2025 to the 11th of November 2025 using four downward facing camera traps placed approximately 50 meters apart in comparable chenopod habitat in each treatment and control plot. All images were manually processed to identify TBGW within the software Timelapse. TBGW activity was indexed by using presence rates which were calculated by taking the number of days per season each camera had at least one TBGW image and dividing this by the cumulative number of days all four cameras were operational for each season. We conducted targeted collections of TBGW scat by focusing our collection efforts around and under chenopod shrubs over three days in March and July 2025. We collected dry bird scats that were deposited by unknown birds for later identification using DNA metabarcoding. File: patch_scale_data.csv Description: Data for patch scale analysis Variables Treatment: Identifies Kangaroo grazing (control) and kangaroo exclusion (treatment) plots. Pair.num: Identifies unique plots within each treatment. season: Seperates different sampling periods in 2025) n.days.present: Summed number of days TBGWs were photographed on all unique cameras within each pot n.camera.days: Summed number of days all cameras were operating for within each plot. Chenopods.prop: Proportional chenopod shrub cover (Chenopod shrub count/total intercepts) Understory.prop: Proportional understory cover (Understory count/total intercepts) File: landscape_data.csv Description: Data for landscape scale analysis Variables Paddock: Unique paddock name Distance.from.AWP.m: Monitoring sites distance from closest artifical water point. n.days.TBGW.present: number of days that TBGW were identified to have been recorded at each site n.days.recording: The number of days son meters were recording for at each site. Prop.Chenopod.shrub.cover: Proportional chenopod shrub cover (Chenopod shrub count/total intercepts) Prop.understory.cover: Proportional Understory cover (Understory count/total intercepts) File: TBGW_plant_diet_dray.csv Description: Number of TBGW scats where plant DNA was idenfied Variables Plant.Genus: Genus of plant identified in TBGW scat n.scats.present.(total=67): number of scatsd genus was identified in. life.form: Broad description of plant genus growth form. File: TBGW_invertebrate_prey.csv Description: Number of TBGW scats where invertbrate DAn was identified Variables Invert.Family: Family of Invertebrates that were identified in TBGW scat n.scats.present.(total=67): Number of scats family was identified in. Prey.Diet: General diet of invertebrate family identified in scat.