Relocation and recapture in Michigan
We erected 11 automated telemetry towers in Michigan which allowed us to detect tagged individuals as they arrived at the majority of breeding sites. Birds arrived between May 9 and June 3. We downloaded tower data daily and used handheld telemetry to search the few areas not well covered by towers at least every three days. We used these data to determine arrival dates in Michigan. Following initial detection, we used handheld telemetry to locate each individual’s territory and target them for recapture. Birds were captured an average of 7.7 (SD ±8.1). days after their first detection in Michigan. We also attempted to recapture birds towards the end of the breeding season in early July. In May of 2018, we also captured and sampled non-tagged Kirtland’s Warblers to compare microbial variation in individuals known to be from Cat Island with birds that may have wintered on other islands. Regardless of timing, we used identical capture and sampling protocols as those used in The Bahamas (see above).