For the purpose of describing the birds' feeding
. zone, the number of seconds each observed bird
spent in each of 16 zones was recorded. (In the
summer of 1956 the seconds were counted by
saying "thousand and one, thousand and two, ... "
all subsequent timing was done by stop watch.
When the stop watch became available, an attempt
was made to calibrate the counted seconds. It
was found that each counted second was approximately 1.25 true seconds.) The zones varied with height and position on branch as shown in Figure
2. The height zones were ten foot units measured
from the top of the tree. Each branch could be
divided into three zones, one of bare or Iichencovered base (B), a middle zone of old needles (M), and a terminal zone of new (less than 1.5
years old) needles or buds (T). Thus a measurement in zone 1'3 was an observation between 20 and 30 feet from the top of the tree and in the
terminal part of the branch. Since most of the
trees were 50 to 60 feet tall, a rough idea of the
height above the ground can also be obtained from
the measurements