Peak Fall Migration Windows for 1000 U.S. Cities

One of many frequent questions posed to the BirdCast team about bird migration is when is peak bird migration in my area? Good question! And a question that we can answer for most cities in the contiguous United States.

Broadly, fall migration runs from approximately 1 August to 30 November (though some species migrate earlier and later than this window) in the contiguous U.S. We try to capture particularly intense periods of migratory movements by defining what we call peak periods: seasonal windows during which 50% of total nocturnal bird migration traffic historically passes through each city (n.b. with values taken from the radar nearest to the city). This peak period date range is determined be examining radar measurements from the last two and a half decades. More detailed discussion and methods are available in this publication.

Knowing when the peak period of an area is can help inform birding excursions, public interest and engagement, and conservation action: for example, it can help with making plans for visiting a particular area to try to maximize the chances of seeing large numbers of birds there, and it can also inform people what days it is most critically important to participate in turning out lights to reduce the collision risk and other hazards created by light pollution for migratory birds.

What we present in the sortable table below is information about the peak periods of fall bird migration by city and state for the 998 largest cities in the contiguous US (two, additional large cities rounding out the list of 1,000 are outside the contiguous U.S.). Each city’s interval of peak period dates is shown in the last two columns in green and red.

Click on the link below to expand the table and explore!

Peak Fall Bird Migration Periods for US cities