The clutch size, incubation rhythm of Reeves’s Pheasant (Syrmaticus
reevesii) and their responses to ambient temperature and precipitation
Abstract
Clutch size and incubation rhythm are critical components of avian life
history. Incubating birds must balance the trade-offs between their
energy requirements and the thermal needs of the developing embryos.
Reeves’s Pheasant (Syrmaticus reevesii) is a uniparental bird endemic to
China that lives in mountain forests, and female Reeves’s Pheasants may
adjust their incubation behavior to cope with cold environments and
energy stress. Using satellite tracking, we tracked 21 wild female
Reeves’s Pheasants in northern Hubei Province, China from 2020 to 2022,
and explored the birds’ clutch size, incubation rhythm and their
responses to ambient temperature and precipitation. The average clutch
size of Reeves’s Pheasant was 7.72 ± 1.51, showing strong seasonal
declines, and was markedly affected by the average temperature during
the spawning period. During the incubation period, the females took 0.74
± 0.46 recesses per day with an average recess duration of 99.23 ± 72.93
mins and an average nest attendance of 93.11 ± 5.06%. There was a peak
of nest departures at around 13:00, and the recess duration was
significantly negatively correlated with both daily mean temperature and
daily precipitation. Our findings demonstrated that female Reeves’s
Pheasants adjusted their behavior in response to the changing ambient
temperature and precipitation, and the unimodal pattern of recess timing
may not be driven primarily by the physiological needs of incubating
females, but by the thermal needs of their developing embryos.