San Francisco Bay to the tip of Baja 
California. All three subspecies are be- 
set by problems, mostly due to loss of 
habitat, but thus far only the California 
least tern has been listed as endangered. 
The California least tern has tradi- 
tionally nested on beaches and salt flats 
adjacent to estuaries, feeding on small 
fish taken from a wide range of habi- 
tats — estuaries, open ocean, rivers, and 
lakes. The terns usually arrive in Cali- 
fornia in mid- or late April, and for 
several weeks engage in aerial courtship. 
One frequently observed aerial display 
is the fish flight, initiated by a male 
carrying a small fish and calling as he 
flies. He is joined by one and sometimes 
two other least terns (presumably fe- 
males) for some fast and vocal high 
flying. Another spectacular display is 
the aerial glide — formation flying by a 
pair that rise high in a weaving pattern 
and then soar downward in unison in a 
beautiful glide. At night the terns con- 
gregate at roosting sites on beaches, 
using the same locations year after year. 
The ground phase follows aerial court- 
ship and is characterized by acts that 
help cement the pair bond, with court- 
ship feeding of females by their mates 
one of the most important rituals. Copu- 
lation is frequent at this stage. The male 
Undaunted by the proximity of 
sunbathers, California least terns loaf 
on the beach in Venice, California. 
Developed extensively in recent 
decades, this coastal community was a 
tern nesting site until human 
disturbance finally drove the birds off 
the beach in the early 1960s. When 35 
pairs reestablished a colony in 1977, 
however, protective fencing was 
quickly erected around the nesting 
area. About 1 50 pairs nested on the 
beach in 1980, making the colony the 
largest in the state. 
