how long do mocking birds stay in the nest
11 to 13 days
Northern mockingbird
 Variation in begging and more compact movements such as perching, fear crouching, and stretching appeared by the ninth day. Wing-flashing, bathing, flight, and leaving the nest happened within seventeen days (nest leaving occurred within 11 to 13 days).
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Northern mockingbird [SEP] Ontogeny
A laboratory observation of 38 mockingbird nestlings and fledglings (thirty-five and three, respectively) recorded the behavioral development of young mockingbirds. Notable milestones included the eyes opening, soft vocalizations, begging, and preening began within the first six days of life. Variation in begging and more compact movements such as perching, fear crouching, and stretching appeared by the ninth day. Wing-flashing, bathing, flight, and leaving the nest happened within seventeen days (nest leaving occurred within 11 to 13 days). Improvements of flight, walking and self-feeding took place within forty days. Agonistic behavior increased during the juvenile stages, to the extent that one of two siblings living in the same area was likely killed by the other.