Dr. David Aborn, Associate Professor of Biology, Geology and Environmental Science at The University of Tennessee at Chattanooga, gave an amazing presentation at our monthly Sierra Club meeting on February 25.

Dr. Aborn gave us interesting facts on bird migration. He distinguished that migration is the periodic movement between 2 consistent locations, with a leave and return pattern. On the other hand, dispersal is movement without return. There are various types of migration. Complete migration has no overlap in breeding and non-breeding areas, and all individuals migrate. North American Warblers, Thrushes and Flycatchers are birds that follow a complete migration pattern. Partial migration is where some individuals leave the breeding area, but not all. Typically the individuals in the northernmost regions of the breeding area are the ones who leave. This type is the most common kind of migration. Sparrows, Wrens and Red-tailed Hawks all partially migrate.

When in migration, various birds fly at different speeds and altitudes. Air currents cause birds to adjust their altitude to find the calmest air or best tailwinds. Seabirds, on the other hand, fly low- typically less than 50 ft- over the water in order to catch updrafts off the waves.

• Songbirds fly at 10-30 mph

• Shorebirds fly at 25-40 mph

• Waterfowl, loons fly at 30-50 mph

• Hawks fly around 50 mph

Dr. Aborn also highlighted the importance of one of his favorite subjects: stopover sites. During the migration journey, birds will stop periodically in order to rest, seek shelter, refuel and replenish fat.

Overall, there was a lot of great discussion and interesting facts shared by Dr. Aborn. Birds are such an important part of our global ecosystem, and populations are unfortunately in decline. Ramping up conservation efforts, preserving habitats, and expanding protections for aviators are critical to birds’ survival.