Migration alert: Cave Swallow time in the East?

Andrew Farnsworth The Cornell Lab Oct 16, 2020

With the passage of a significant frontal boundary on Friday through the northeastern US comes the first solid opportunities for out of “typical” range Cave Swallows to occur. Birders in coastal and lakeshore locations throughout the eastern US should keep a keen eye on all swallows with the passage of this weather system and during passing weather systems in the 2-3 weeks that follow.

A cold front, the blue line with blue triangles, will push off the Atlantic Coast of North America on Friday evening. The passage of this weather system marks a beginning to a period when birders should be watching for Cave Swallows, a rare but regular occurrence in eastern North America during autumn often associated with such systems’ passages.

What is the recipe for Cave Swallows in the eastern US? Well, a recipe (we do not necessarily profess to know all of the ingredients!) follows: large numbers of an aerial species prone to entrainment in and displacement by well organized low pressure systems tracking through or just north of the Great Lakes and associated distinct frontal boundaries that bring strong southwesterly winds with their approach.