Every autumn since 1983, an annual ritual on what birders call "Hawk Hill", in the Marin Headlands, takes place.
They point binoculars and scopes to take a census of nineteen species, roughly 40,000 birds a year.
The birds have flown this route long before the Army was here, or people.
In fact, their patterns trace back to the last ice age.
Now, as the climate changes again, Allen Fish of the Golden Gate Raptor Observatory wonders how it affects these creatures at the top of the food chain.
This year, they'll look closely at the rough legged hawk, which travels all the way from the arctic.
The numbers show that in the past twenty-five years.
The rough legged hawk has arrived five days later, which may not sound like much.
"It might be a statistical blip or a trend with serious implications because nature is interconnected.
"We're talking about is a potential to desynchronize a huge range of biological events," said Allen Fish, Golden Gate Raptor Observatory. Read More...
Tags: Birds, Climate Change, Global Warming