DISCUSSION
Gut microbiota of Kirtland’s Warblers change as individuals and
populations migrate from the wintering grounds in The Bahamas to
breeding territories in Michigan. Repeated sampling at multiple points
across the annual cycle was only possible because we were able to
capture, sample, and radio-tag individuals on the wintering grounds and
then use automated telemetry to relocate the same individuals thousands
of kilometers away on the breeding grounds (Cooper and Marra 2020).
Through the resampling of individuals we remove potential biases
associated with sampling multiple populations. Therefore, the effects
observed can be attributed to true changes within individuals and our
study population. We found that period within the annual cycle exerts a
notable effect on the overall diversity of the microbiome and birds on
their wintering grounds have a significantly different and more diverse
community of gut microbiota than those on their breeding grounds. We
also identified a common, core microbial profile of Kirtland’s Warbler
that persisted throughout multiple portions of the annual cycle.