 The egg size is independent of the clutch size and the nest site , but may vary between different females . The female incubates for 17 – 18 days before the altricial downy chicks are hatched , and is fed at the nest by the male . The female broods the newly hatched chicks for around ten days , and then both parents share feeding and nest sanitation duties . The chicks fledge 31 – 41 days after hatching . 
