Singing rate in relation to breeding stage
Discrete song rate varied significantly among the six breeding stages
(Analysis of Deviance: χ2 = 19.65, df = 5, P =
0.0015; Figure 4). Post-hoc linear contrasts showed that discrete song
rate did not differ between the breeding and non-breeding seasons
(estimate ± SE (log scale): -0.39 ± 1.21; Z = -0.32, P = 0.7489).
Within the breeding season, however, discrete song rate was higher for
males with no nesting duties than for males with nesting duties (mean of
nest building, egg stage, nestling care, and fledgling care; estimate ±
SE (log scale): 2.78 ± 0.81; Z = 3.46, P = 0.0005). Discrete song
rate also was lower during nestling care than during other nesting
stages (mean of nest building, incubation, and fledgling care; estimate
± SE (log scale): -2.87 ± 0.99; Z = 2.89, P = 0.0039).