Determination of incubation behavior
The ODBA of female Reeves’s Pheasants was low and stable during
incubation but changed rapidly when incubation was interrupted. Thus,
the beginning of incubation was determined from a sharp decline in ODBA,
the interruption of incubation was determined from a sharp increase in
ODBA, and constant ODBA was interpreted as continuous incubation
(Figure 2). Based on the changes
in ODBA, we determined whether the females started to incubate, then
searched for their nests according to the location information, and
recorded clutch size and related nest site information.
The first day of incubation was determined based on changes in ODBA, and
the first egg-laying date was determined by clutch size and the number
of periodic visits by females to the nest before incubation started. Due
to this remote monitoring system, there was no need to visit targeted
nests frequently during the incubation period, which minimized human
disturbance and the possible risk of nest predation.
Definition of incubation parameters
Observations and records for this study were made over a 24-hour period
starting at 0:00 and ending at 24:00 every day. Since the first and last
incubation days were not complete (0:00-24:00) monitoring days, they
were not included in the analysis. For each complete monitoring day of
each nest, we calculated: (1) recess frequency, estimated as the number
of times a female left the nest per day; (2) recess duration, estimated
as the total recess length (in minutes) per day; (3) nest attendance,
estimated as the proportion of 24 hours a female devoted to incubation
per day.