. ▁This ▁can ▁be ▁another ▁mechanism ▁to ▁how ▁the ▁Cass ia ▁cross b ill ▁diver ged ▁from ▁the ▁red ▁cross b ill . ▁ ▁Re production ▁The ▁Cass ia ▁cross b ill ▁and ▁the ▁other ▁red ▁cross b ill ▁call ▁types ▁will ▁strongly ▁associate ▁with ▁their ▁own ▁call ▁types . ▁Between ▁ 2 0 0 1 ▁and ▁ 2 0 0 6 , ▁less ▁than ▁ 1 % ▁of ▁Cass ia ▁cross b ills ▁pa ired ▁with ▁other ▁call ▁types . ▁Comp ared ▁to ▁the ▁red ▁cross b ill ▁call ▁types , ▁which ▁are ▁opportun istic ▁bre ed ers ▁throughout ▁most ▁of ▁the ▁year , ▁the ▁Cass ia ▁cross b ill ▁will ▁consist ently ▁bre ed ▁from ▁March ▁through ▁July . ▁They ▁tend ▁to ▁build ▁their ▁cup - sh aped ▁n ests ▁in ▁April , ▁using ▁tw igs , ▁grass es ▁and ▁need les . ▁Court ship ▁of ▁the ▁cross b ills ▁involves ▁the ▁male ▁attract ing ▁the ▁female ▁by ▁singing , ▁flying ▁and ▁feed ing ▁them ▁with ▁p ine ▁se eds . ▁M ales ▁will ▁ag gress ively ▁defend ▁the ▁female ▁from ▁other ▁bre eding ▁males ▁after ▁cop ulation ▁successfully ▁occurs . ▁Fem ales ▁will ▁lay ▁ 2 – 6 ▁eggs ▁and ▁they ▁will ▁inc ub ate ▁the ▁egg ▁for ▁ 1 2 – 1 6 ▁days . ▁ ▁Conserv ation ▁and ▁status ▁The ▁current ▁total ▁population ▁estimation ▁is ▁ ≈ 5 , 8 0 0 ▁individuals . ▁Since ▁the ▁Cass ia ▁cross b ill ▁is ▁a ▁new ▁species , ▁the ▁conservation