Assessing Radio Transmitter Weight Effect and Evaluation of Northern Bobwhite Chick Survival in Coastal North Carolina

Abstract Studies on the earliest life stages are essential to our ecological understanding of avian demography; however, monitoring technologies that allow tracking of small birds are still limited in a variety of ways. One critical limitation, until recently, has been the development of methods for attaching transmitters to young birds with precocial development (e.g., Galliformes, Charadriiformes, etc.). The modified suture technique offers a means to attach transmitters to precocial chicks while accommodating rapid growth characterized by birds with precocial young. Although the sutured transmitter method was developed for northern bobwhite (Colinus virginianus) chicks, there remain key unknowns regarding best practices for use in the field. One key consideration with transmitters attached to birds is understanding the impacts of tag weight on individual demography. Herein, we quantified daily survival rates (DSR) for 263 11‐to‐13 day‐old northern bobwhite chicks monitored from 2022 to 2024 in Brunswick County, NC, USA, and assessed the effect of transmitter weight (1.2 g vs 0.8 g) on DSR. We observed mortality of 167 (62%) radio‐tagged chicks during our study. Estimated DSR from mixed effects linear regression analysis was 0.957 (95% CI = 0.946–0.966). Daily survival rate also varied with ordinal date (β = −0.02), but transmitter weight did not explain variation in DSR. Our results suggested that researchers may be better served by a 1.2‐g transmitter as it yields greater detectability and longevity with no survival consequence. Our results provide insights into the factors driving natural variation in survival for bobwhite chicks (i.e., ordinal date) while also providing guidance on transmitter size to inform future work on early life stages in a declining species.