s ines ci ur is ” ▁means ▁“ without ▁squ ir rel ”. ▁Initial ly , ▁it ▁was ▁considered ▁one ▁of ▁the ▁Red ▁Cross b ills ’ ▁ 1 0 ▁call ▁types , ▁which ▁had ▁different ▁vocal izations , ▁bill ▁size ▁and ▁were ▁for aging ▁for ▁different ▁con ifer ▁species . ▁The ▁idea ▁of ▁re product ive ▁isol ation ▁between ▁call ▁types ▁was ▁suggested , ▁but ▁direct ▁evidence ▁was ▁lack ing . ▁In ▁ 2 0 0 7 , ▁some ▁anal ys es ▁found ▁that ▁different ▁call ▁types ▁were ▁gen et ically ▁different ▁including ▁the ▁South ▁Hills ▁cross b ill ▁( call ▁type ▁ 9 ). ▁Furthermore , ▁evidence ▁suggested ▁that ▁the ▁South ▁Hills ▁cross b ill ▁was ▁in ▁a ▁co e volution ary ▁arms ▁race ▁with ▁the ▁l odge pole ▁p ine , ▁further ▁leading ▁to ▁habitat ▁isol ation . ▁In ▁ 2 0 1 6 , ▁it ▁was ▁identified ▁as ▁ph y log en et ically ▁distinct ▁from ▁the ▁other ▁call ▁types . ▁This ▁is ▁an ▁example ▁of ▁sym pat ric ▁spe ci ation . ▁In ▁ 2 0 1 7 , ▁the ▁A OU ▁reached ▁a ▁cons ensus ▁and ▁split ▁the ▁South ▁Hills ▁cross b ill ▁from ▁the ▁red ▁cross b ill ▁and ▁rename ▁it ▁the ▁Cass ia ▁cross b ill , ▁because ▁its ▁habitat ▁res ided ▁in ▁Cass ia ▁County , ▁Id aho . ▁ ▁Be hav iour ▁ ▁Diet ▁The ▁Cass ia ▁cross b ill ▁will ▁exclus ively ▁for age ▁for ▁l odge pole ▁p ine ▁con es