Influence of Woody Vegetation Patterns on Overwinter Spatial Ecology and Demographics of Scaled Quail
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Scaled quail are a small gallinaceous upland game bird that has exhibited population declines throughout their geographic range over the past four decades. The Texas Rolling Plains scaled quail populations decline 79% between1978 to 1980 based on Texas Parks and Wildlife August roadside counts. Many factors have been attributed to Scaled quail declines such as habitat loss and fragmentation, increased predation, and disease however, consideration of environmental stressors and changes in landscape patterns and their influence on scaled quail population demographics have been minimally explored. Semi-arid landscapes such as the Texas rolling plains have experienced shifts in vegetation structure over the past century resulting in dense woody vegetation and fragmented landscapes. Limited research has addressed changes in landscape pattern effects on scaled quail populations integrated with comparisons of habitat resource selection and microclimate. The goal for this study was to quantify the relationship among woody vegetation and scaled quail winter parameters. My objectives were to 1) analyze landscape vegetation metrics and woody vegetation patterns using aerial drone images paired with ground vegetation surveys, 2) assess spatial ecology to estimate home range and core area sizes and assess habitat selection characteristics at multiple spatial scales and, 3) Assess and compare scaled quail winter survival within the context of landscape parameters quantified in objective 1. I monitored scaled quail (n=187) via GPS and VHF on 4 ranches throughout the Texas Rolling Plains. The ranches were divided into 2 stable and 2 intermittent population sites. I defined ranches that are composed of large grassland tracts roughly 45% of total area with relatively low woody cover percentage (approximately 25−30%) and have relatively abundant SCQU populations as determined from annual surveys from Quail Tech as stable population ranches. The majority of the ranches I sampled limited or no scaled quail so I only completed the project objectives on 1 intermittent site (Dickens County) and one stable site (Potter County). I defined ranches with small, fragmented tracts of suitable cover, grassland tracts <45% and woody vegetation densities >25-30%, as intermittent population ranches. I utilized the Sensefly EBee fixed wing mapping drone to gather real-time high-resolution images to assess ranch level and higher spatial scale habitat selection and paired the images with ground vegetation surveys and microclimate data for land use land cover classification to assess multiple spatial scale habitat selection and over winter survival. I quantified scaled quail home ranges and core areas using Brownian Bridge movement model in program R at 50% and 90% isopleths respectively GPS tagged Scaled quail (n=27) and assessed habitat selection at the 2nd, 3rd and, 4th order spatial scales. I used the Nest Survival Model in Program Mark to assess overwinter survival between transmitter types, between and among ranches and, and between various vegetation and microclimate measurements obtained from my field methods (Exposure Period = 172 days: SE=0.52, UCL = 0.24, 95 % 95% LCL = 0.67). A combination of the results from each chapter of this study suggest reducing bare ground on the landscape to ~10% and maintaining woody vegetation to 25-30% (based on FRAGSTATS results) within 300 ha patches maximizes overwinter survival for SCQU on the Texas Rolling Plains.