Turkey Vulture photographed 01/12/2023 at the San Jacinto Wildlife Area, SoCal, USA.
I don't know how many people are aware that many (most?) turkey vultures migrate vast distances (thousands of miles, in some cases) every fall and spring from North America to as far south as Patagonia and back again. I know I wasn't aware of it.
They are one of the three big stars in one of the largest visible migrations on planet earth, popularly known as the Veracruz River of Raptors. In the months from September-November every fall, 1-2 million turkey vultures pass over a narrow plain in Veracruz, Mexico, flying south from spots all over North America. Even more Swainson's Hawks and Broad-Winged Hawks do the same. In total, as many as 4-6 million raptors pass through each fall. (And hundreds of thousands of white pelicans, wood storks, and other birds.)
On many days during the fall migration, it's possible to see 200,000-400,000 birds fly by in a 6-hour period (they typically fly from around 10am to 4pm because that's when the thermals provide lift).
I spent about 8 days watching it this last October. Truly astounding on a big day. The sky fills with birds in, well, a river streaming south. In your field of view, you can easily see thousands of hawks and vultures at once, all mixed together, in streams and in the spirals (called "vortexes" or "kettles") that they use to periodically gain altitude for their next soaring leg.
Short description:
https://fieldguides.com/bird-tours/mexico-veracruz/
Quick video that gives a taste:
In Veracruz, there is also a native vulture, called the Lesser Yellow-Headed Vulture, which is visually very striking. We saw quite a few of these out in the fields, and could photograph them quite closely. I wasn't photographing on this trip, but here's a shot from Wikipedia:
