▁cl utch ▁of ▁four ▁eggs . ▁The ▁diameter ▁and ▁length ▁of ▁an ▁egg ▁is ▁typically ▁around ▁ 3 . 5 ▁cent im eters ▁and ▁ 2 . 6 ▁cent im eters ▁respectively . ▁The ▁eggs ▁generally ▁we igh ▁around ▁ 1 0 - 1 3 ▁gr ams . ▁The ▁eggs ▁are ▁p ear - sh aped , ▁and ▁they ▁are ▁gray ish ▁brown ▁or ▁bl u ish ▁gray ▁in ▁color ▁with ▁tiny ▁brown ▁sp ots . ▁Both ▁male ▁and ▁female ▁take ▁part ▁in ▁nest ▁maintenance . ▁They ▁line ▁their ▁nest ▁with ▁small ▁p eb bles , ▁tw igs , ▁small ▁pieces ▁of ▁b ark , ▁and ▁other ▁dry ▁plant ▁parts . ▁Both ▁male ▁and ▁female ▁also ▁carry ▁out ▁inc ub ation ▁of ▁eggs . ▁E gg s ▁normally ▁h atch ▁ 2 9 ▁days ▁after ▁the ▁start ▁of ▁inc ub ation . ▁Inc ub ation ▁period ▁can ▁vary ▁because ▁of ▁human ▁disturb ance . ▁Long - bil led ▁p lo vers ▁show ▁a ▁decent ▁amount ▁of ▁parent al ▁care . ▁If ▁a ▁pred ator ▁approaches ▁a ▁nest , ▁the ▁parents ▁try ▁to ▁int im id ate ▁the ▁enemy ▁and ▁ch ase ▁it ▁away ▁by ▁making ▁loud ▁dist ress ▁calls . ▁Furthermore , ▁on ▁very ▁hot ▁summer ▁days , ▁the ▁parents ▁protect ▁the ▁eggs ▁from ▁over he ating ▁by ▁standing ▁over ▁them ▁and ▁sh ading ▁them ▁from ▁the ▁sun . ▁Long - bil led ▁p lo vers ▁give ▁birth ▁to ▁pre co cial ▁off spring , ▁meaning ▁that ▁the ▁h atch lings ▁can ▁move