<p>
There are five subspecies of Black-necked Stilts (<i>Himantopus himantopus</i>).
The American Ornithologists' Union calls the American version
<i>Himantopus mexicanus</i> and internationally it
is called <i>Himantopus himantopus mexicanus</i>.
</p>
<p>
Black-necked Stilts are found in North and South America.
They are fairly common in the San Francisco Bay Area
where they breed.
</p>
<p>
Sexes are similar but 
females are recognizable because their backs are brownish instead of
black.
Black-necked Stilts will flock together except when roosting.
Then they spread out.
They work together to discourage predators.
</p>