3.3 The effect of male ornamental traits and temperature on
parental investment during incubation.
We
observed a high degree of consistency in both female and male incubation
behavior across days (female: R = 0.621, confidence interval [CI]:
0.463, 0.741; male: R = 0.468, CI: 0.274, 0.626; Figure S5). This
finding suggests that individual birds have a consistent incubation
investment strategy.
Our results showed that the combined total incubation investment from
both parents decreased with increasing ambient temperature (Estimate
(95% CI) = -0.327 (-0.620, -0.047), z = -2.967, p = 0.003). This
finding suggests that temperature is an important environmental factor
that increases the overall
incubation
investment of plovers.
We observed that larger females invested more time in incubation
compared to smaller females, as shown by a positive correlation between
female incubation investment and individual tarsus length (Table 3). On
the other hand, male ornamentation was found to play a role in their
incubation strategy, as indicated by a significant interaction between
male ornamentation and ambient temperature (Table 3, Figures 2a).
Specifically, we found that more ornamented males decreased their
incubation investment at warmer temperatures but increased it in colder
temperatures
(Table
3, Figures 2a, d, S6), suggesting that the effect of ornamentation on
male incubation investment varies depending on the ambient temperature.