Summary

In this episode, Ivan Phillipsen explores the fascinating world of subspecies—the diversity that exists within bird species. Learn how these populations arise, why ornithologists sometimes struggle to define them, and what makes the concept so important for both science and conservation.

From the record-breaking Island Thrush, once thought to have more subspecies than any other bird, to chickadees, sparrows, and hawks closer to home, Ivan shares examples that highlight just how complex and surprising intraspecific variation can be. Along the way, he touches on genetics, evolution, and the challenges of naming and classifying birds in a way that truly reflects reality.

Whether you’re a birder, a naturalist, or just curious about how new species begin, this episode offers a clear and engaging look at the “gray zone” between populations and species—and why it matters for birding, science, and conservation.

Research Citations

• Population genomics of the island thrush elucidates one of earth’s great archipelagic radiations
• Extensive phenotypic diversification coexists with little genetic divergence and a lack of population structure in the White Wagtail subspecies complex (Motacilla alba)

Photos