Berardi is the treasurer of the Hawk Migration Association of North America, an organization that monitors raptor populations across North America through migration population counts.
The most intense raptor rapture, however, lies outside the United States. Veracruz, Mexico, draws four to eight million raptors in the end of September and beginning of October. "You're watching tens of thousands of hawks milling around in the sky," said Fish, of the Golden Gate Raptor Observatory. "It hits you right in your gut, in your heart."
But many hawk hot spots across the U.S. offer birders a chance to view raptor migrations. "Anywhere on the continent, you're not too far away," said Goodrich, the Hawk Mountain Sanctuary biologist.
The Hawk Migration Association of North America provides a list of hawk-count sites around the country, with sites in 41 states.
Prime viewing spots include coastlines and mountain ranges, which provide the birds updrafts for easy soaring. (Hawks appear to avoid crossing large bodies of water, preferring, for example, to avoid the Great Lakes by flying through small passageways around the lakes.)
In the San Francisco Bay area, hawks may hew to the coast more out of an urge to conserve energy using the wind, rather than a fear of the open bay, Fish said.
Some hawks travel thousands of miles on their southward journey. The peregrine falcon can fly all the way from the Alaska tundra to the prairies of central Argentina.
Other hawks make shorter treks. Red-tailed hawks spotted near San Francisco's Golden Gate Bridge, for example, may have flown from British Columbia, Fish said. Or they could be local hawks moving within the area to search for a sport with better prey or fewer competitors.
"The trouble is that you can't look up at a red-tail and see its travel visa," Fish said.
How to Hawk-Count
Hooking up with an experienced hawk-watcher is often the best advice for fledgling birders who want to learn identify the raptors.
Berardi recalled his first hawk-counting experience a decade ago in Duluth, Minnesota, another hawk hot spot. The first day out, he saw about 50 birds. The hawk-counter next to him spotted 500. "The next day, I started watching him instead of the sky," Berardi said.
Many hawk-count sites offer lectures, how-to talks, and docents who answer raptor questions during the fall migration. Such sites also rely on volunteers to assist during seasonal hawk counts.
Hawk Mountain, Pennsylvania, for example, has been recording hawk numbers since 1934. It is one of the longest-running count programs in the world.
The data can be used to gauge everything from a species' well-being to learning about range and change within a population.
Hawk counts can also be used to conserve damaged species. In her classic environmental book Silent Spring, naturalist Rachel Carson used counts of bald eagles from Hawk Mountain to show the affect of DDT on eagle populations.
More recently, hawk counts have shown population changes in sharp-shinned hawks over the last few decades.
Today, Hawk Mountain is working with the Hawk Migration Association of North American and HawkWatch International, a Salt Lake City, Utah-based conservation group, to pool data from hawk watch sites across the continent.
"If we can pull together three or four sites from the same flyway, we'll have a better idea of what's happening with these species," Goodrich said.
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