Wildlife researchers have long tried to understand why birds fly in flocks and how different types of flocks work. A new study from the University of North Carolina at Chapel Hill explores the mechanics and benefits of the underlying flock structure used by four types of shorebirds. Understanding more about how these birds flock moves researchers a step closer to understanding why they flock.
The study, led by Aaron Corcoran, a postdoctoral researcher studying bat and bird flight and ecology, and biology Professor Tyson Hedrick of UNC-Chapel Hill, appears in the June 4 issue of eLife. The National Science Foundation funded the work.
In the study, the researchers focused on four types of shorebirds that vary in size: dunlin, short-billed dowitcher, American avocet and marbled godwit. Corcoran and Hedrick filmed and analyzed almost 100 hours of video footage to better understand the mechanics of shorebird flocks. They found that the birds fly in a newly defined shape the team named a compound V-formation, which they believe provides an aerodynamic advantage and predator protection.
This compound formation is a blend of two of the most common flock formations. One is a cluster formation, common with pigeons, where a large number of birds fly in a moving three-dimensional cloud with no formal structure. This structure is useful for avoiding predators. The second is a simple V-formation, commonly used by Canada Geese, where a smaller number of birds will line up in a well-defined two-dimensional V-shape.