 A nestling begins to give the ' chip ' call soon after it emerges from the egg , and it calls frequently for the first two thirds of the nestling period and constantly for the last third . The call does not vary in the presence of an adult at the nest , so it seems likely that the call is not directed at the adult bird . The nestling becomes silent when an adult gives an alarm call , and makes a squealing sound when the adult delivers food . The begging call of a fledgling is similar to the call of the nestling , but significantly louder and covering a greater frequency range ( which may make it more directional ) . The rate of calling , on average , is 85 to 100 calls in a minute , and in open scrub the call can be heard up to a kilometre away . Subsong , a juvenile vocalization comprising elements of various calls , begins to be uttered when the fledgling is around thirty days old . 
 A nestling <a href='uninflect' title='1'><mark>begins</mark></a> to give the ' chip ' call soon after it <a href='uninflect' title='2'><mark>emerges</mark></a> from the egg , and it <a href='uninflect' title='3'><mark>calls</mark></a> frequently for the first two thirds of the nestling period and constantly for the last third . The call <a href='uninflect' title='4'><mark>does</mark></a> not vary in <a href='None' title='5'><mark>the</mark></a><a href='negative_concord' title='6'><mark>presence</mark></a> of an adult at <a href='None' title='7'><mark>the</mark></a><a href='negative_concord' title='8'><mark>nest</mark></a> , so it <a href='uninflect' title='9'><mark>seems</mark></a> likely that the call is not directed at <a href='None' title='10'><mark>the</mark></a>adult <a href='negative_concord' title='11'><mark>bird</mark></a> . The nestling <a href='uninflect' title='12'><mark>becomes</mark></a> silent when an adult <a href='uninflect' title='13'><mark>gives</mark></a> an alarm call , and <a href='uninflect' title='14'><mark>makes</mark></a> a squealing sound when the adult <a href='uninflect' title='15'><mark>delivers</mark></a> food . The begging call of a fledgling <a href='drop_aux' title='16'><mark>is</mark></a>similar to the call of the nestling , but significantly louder and covering a greater frequency range ( which may make it more directional ) . The rate of calling , on average , <a href='drop_aux' title='17'><mark>is</mark></a>85 to 100 calls in a minute , and in open scrub the call can be heard up to a kilometre away . Subsong , a juvenile vocalization comprising elements of various calls , <a href='uninflect' title='18'><mark>begins</mark></a> to be uttered when the fledgling <a href='drop_aux' title='19'><mark>is</mark></a>around thirty days old . 
A nestling begin to give the ' chip ' call soon after it emerge from the egg , and it call frequently fa da first two thirds of the nestling period and constantly for the last third . The call do not vary in no presence of an adult at no nest , so it seem likely dat tdacall ain't directed at adult no bird . The nestling become silent when an adult give an alarm call , and make a squealing sound when the adult deliver food . The begging call of a fledgling similar to thdaall of the nestling , but significantly louder and covering a greater frequency range ( which may make it more directional ) . The rate of calling , on average , 85 to 100 calls in a minute , and in open scrub thedall can be heard up to a kilometre away . Subsong , a juvenile vocalization comprising elements of various calls , begin to be uttered when the fledgling around thirty days old .