ins . ▁▁ ▁The ▁n ests ▁can ▁be ▁more ▁than ▁ 2   m ▁( 6   ft ) ▁in ▁diameter ▁and ▁nearly ▁ 1   m ▁( 3   ft ) ▁high . ▁P airs ▁show ▁high ▁f idel ity ▁to ▁the ▁nest ▁site , ▁often ▁ref urb ishing ▁and ▁re using ▁a ▁nest ▁for ▁as ▁many ▁as ▁five ▁bre eding ▁seasons . ▁The ▁cl utch ▁is ▁one ▁or ▁two ▁eggs ▁( rare ly ▁three ▁or ▁four ) ▁which ▁are ▁inc ub ated ▁by ▁both ▁sex es ▁for ▁about ▁ 3 1 ▁days ▁( range ▁ 2 6 – 3 5 ▁days ). ▁E gg s ▁are ▁ch alk y ▁white ▁and ▁we igh ▁about ▁ 2 4 0   gram s . ▁When ▁dist urbed ▁from ▁the ▁nest , ▁parents ▁may ▁sometimes ▁attempt ▁to ▁conce al ▁the ▁eggs ▁by ▁attempting ▁to ▁cover ▁them ▁with ▁material ▁from ▁the ▁edge ▁of ▁the ▁nest . ▁The ▁egg sh ells ▁are ▁removed ▁by ▁the ▁parents ▁after ▁the ▁ch icks ▁h atch ▁either ▁by ▁carrying ▁away ▁the ▁fragments ▁or ▁by ▁sw allow ing ▁them . ▁About ▁ 3 0 % ▁of ▁all ▁bre eding ▁pairs ▁succeed ▁in ▁raising ▁ch icks ▁in ▁any ▁year , ▁and ▁most ▁of ▁the ▁successful ▁pairs ▁raise ▁one ▁or ▁two ▁ch icks ▁each , ▁with ▁bro od ▁sizes ▁of ▁three ▁being ▁rare . ▁One ▁survey ▁in ▁Australia ▁found ▁ 6 0 % ▁of ▁bre eding ▁pairs ▁to ▁have ▁successfully ▁fled ged ▁ch icks . ▁This ▁high ▁success ▁rate ▁is ▁attributed ▁to ▁above