Estimating the proportion of wild northern bobwhite (C. virginianus) receiving anthelmintic treatment in the rolling plains of Texas

Northern bobwhite quail (Colinus virginianus) are a highly sought-after species of upland game bird in North America whose population has been declining over the last half-century. The Rolling Plains Ecoregion of Texas has long been seen as one of the last strongholds for huntable populations of the species. This is the major reason the hunting community was so concerned when the quail population suffered a major crash in 2010 despite predictions of substantial population growth that year. A multi-institute research initiative conducted in response to the crash identified numerous causes for the sharp decline in the C. virginianus population including two parasites, the eyeworm Oxyspirura petrowi and the cecal worm Aulonocephalus pennula. The Wildlife Toxicology Lab at Texas Tech University developed and began delivering a medicated feed to treat wild quail infected with these parasites. Since then, the demonstration sites using the medicated feed have seen dramatic increases in the C. virginianus populations on their properties. The medicated feed uses the anthelmintic drug Fenbendazole and was recently registered for treating wild quail with the United States Food and Drug Administration (FDA). Currently, several FDA-approved demonstration sites are providing medicated feed using feeding systems designed for use by C. virginianus and other quail species. The current practice for these sites is to provide medicated feed for three weeks in the spring and three weeks in the fall. Ongoing research with the medicated feed has been centered around determining best management practices, including best timing of delivery, frequency of delivery, and the proportion of C. virginianus receiving treatment. Early work with the medicated feed estimated that treating 30% of the C. virginianus population would result in achieving the management goal of sustaining huntable populations year after year. The goal of this research was to put that estimate to the test and determine what percentage of a wild population of C. virginianus was probably accessing the medicated feed during the 3-week fall treatment period. To accomplish this, the lab first had to find a way to monitor supplemental feeder usage by C. virginianus. Passive integrated transponder (PIT) tags were chosen as the ideal tool for this purpose but, as they had never been used in C. virginianus in the wild, a proof-of-concept project was required to show that they would be reliable tools for this project. Then, we needed to trap and tag enough quail in the immediate weeks before the treatment period to be representative of the local C. virginianus population and monitor their feeder usage while the medicated feed was made available to them. To do this we designed and installed radio frequency identification (RFID) reader stations around select quail feeders in the field. Then 24 wild C. virginianus were trapped and tagged in the spring of 2024, and the following summer was spent monitoring their feeder usage and adjusting the RFID reader’s antenna to ensure the best possible results. After the proof-of-concept project was completed, and the RFID readers had all been made efficient, we were ready to begin the primary work of this project, estimating the proportion of a wild C. virginianus population receiving anthelmintic treatment during the current FDA-recommended 3-week fall treatment period. One month prior to treatment, 48 additional quail were trapped and tagged along the 18-kilometer route traversing the West Texas ranch this research was conducted on. These 48 were the only quail monitored over the 3-week fall treatment period. After the treatment period ended, the data was collected from the site for analysis and fall covey counts were conducted as part of the WTL’s long-term work monitoring C. virginianus population growth in the area. Of the 48 C. virginianus tagged exactly half were logged by an RFID reader during the treatment period. Ten of these birds were trapped within 2 meters of the feeder they were later logged visiting but the other 14 traveled distances ranging from around 50m to just under 1 km from where they were trapped to access a supplemental feeder. On average a bird visited a feeder for 10 days out of the 21-day treatment period. These visits lasted an average of 3 minutes and 49 seconds. These data not only answered the primary question concerning the proportion of C. virginianus probably accessing the medicated feed during the fall treatment period but also provided us with a better understanding of how wild populations of C. virginianus are using the supplemental feeder systems. This work will not only help develop best management practices for using supplemental feeders to deliver the medicated feed but will have also provided our lab with valuable data for future projects aimed at calculating the amount of drug each quail is being exposed to during treatment. Overall, this work has helped further the collective knowledge of how wild C. virginianus populations are utilizing supplemental feeders and will help inform both landowners and conservationists interested in using them, and the medicated feed, to increase wild C. virginianus populations.