After three decades of consistently and meticulously tallying the daily fall raptor migration at the Golden Gate, we have a lot of great data, and we have an amazing ability to see a kind of baseline raptor migration story for the 19 species that are seen here annually.

For example, what’s the earliest date that you might see a Merlin, a small bird-hungry falcon that doesn’t nest in California? What is the greatest number of Red-tailed Hawks that have been seen in a day? And what’s the latest Broad-winged Hawk to be seen at the Golden Gate before this little buteo finishes its migration in South America?

Records like these are fun for asking casual questions, (Did I just see a record number of Osprey in one day? Well, you did if it was over 36 sightings.) but they are also key markers for scientific questions about raptor migration. For example, an unusually high count on a peak day can tell us something about population trends for that species. An early start date or peak date for a long-distance migrant like the Osprey may be a clue to a climate-related phenological shift. 

Of course, you can also use these charts for planning your trip to Hawk Hill this fall, so you can figure out which day will maximize your chances of seeing a Golden Eagle. See you on October 6th!