From Martin et al. Longer retention of HL fruit results in assimilation of ca. See Johnson et al. If handled, nestlings give faint calls on day 7 and rapid distress cheeps on late day 10. No data from deafened birds to test if birds need to hear themselves practice nor on limits of critical learning period.
Dependent fledglings give a flat chip or tsip at intervals.
Drawing by J. Zickefoose. In forest fragments, in some parts of range, e.g., Midwest, cowbird parasitism reduces the number of Wood Thrush fledged. Second-level calls are about five notes, louder and higher in frequency than first level, expressed as pit, pip, or whit. May escalate to even higher frequency and faster delivery. Early males sing briefly near dawn and dusk within few days after arrival on breeding grounds.