often holds a fish in his bill throughout 
the precopulatory sequence, and the fe- 
male reaches up and takes it from him 
at the moment of cloacal contact. 
As the time for egg laying ap- 
proaches, the pair begin to look for the 
particular spot where the nest will be 
scraped in the sand. They engage in 
elaborate scrape making, moving from 
place to place until the female finally 
selects a site to her liking and scrapes 
out a simple hollow for the eggs. From 
one to three eggs (usually two) are laid 
on consecutive days, after which both 
adults take turns at incubation duties. 
The relative serenity of the incubation 
period is the lull before the storm. After 
about three weeks, the eggs hatch and 
the tempo quickens. The precocial 
chicks begin wandering away from the 
nest scrape a day or two after hatching. 
As this least tern emerged from 
the egg, the first moments 
of its life were captured by the 
photographer. The chick’s cryptic 
coloration provides a 
defense against predators. 
Their diet consists solely of small fish 
brought to them by both parents. Par- 
ents only feed their own chicks, and the 
chicks learn to respond only to the calls 
of their parents as they fly in with fish. 
Since the chicks are extremely mobile, 
and a colony of a hundred pairs of 
California least terns can have 200 
chicks running around simultaneously, 
the communication system must be 
firmly established on the first posthatch- 
ing day. The chicks are on the ground 
for about twenty days after hatching, 
eating voraciously and growing rapidly 
until they are mature enough to fly. 
During both the incubation and post- 
hatching periods, the colony is ex- 
tremely vulnerable, and eggs and chicks 
are regularly lost to ground and aerial 
predators. Disturbance by people can 
also have serious consequences during 
this time as the presence of intruders on 
the nesting grounds keeps adults off 
their eggs or away from their chicks. 
Once the chicks are airborne, the haz- 
ards diminish. 
After fledging, the juveniles begin to 
fish for their own food, practicing in 
local ponds and still-water bays. It takes 
a lot of practice before they acquire the 
skills necessary to feed themselves, so 
parents continue to feed their young 
long after they have fledged. At dusk, 
adults and juveniles congregate at roost- 
ing sites on the beaches where they 
spend the night. These roosting areas 
and postbreeding fishing sites play an 
important role in the life history of the 
least tern, and must be protected along 
with the more obvious nest sites and 
adult fishing grounds. By August the 
nesting season is usually over and migra- 
tion to wintering areas has begun. Fam- 
ily groups are maintained during migra- 
tion, and adults can be seen feeding 
juveniles at fishing and loafing areas en 
route. 
The least terns’ predilection for nest- 
ing on beaches and foraging in estuaries 
was the major cause of their drastic 
decline in numbers. The tremendous 
growth of the human population in Cali- 
fornia after World War II, particularly 
along the southern coast, put pressures 
on the birds that they could not with- 
stand. In terms of breeding habitat, un- 
disturbed beaches became scarce and 
most of California’s estuaries were 
dredged and converted into marinas. 
Colonies that once numbered hundreds 
of pairs were reduced to remnants or 
vanished altogether. But the terns 
showed remarkable adaptability and in- 
genuity in finding substitute nest sites; 
65 
