, ▁except ▁for ▁air ▁movement ▁generated ▁by ▁their ▁rapid ▁wing - be at , ▁possibly ▁a iding ▁con ve ct ive ▁heat ▁loss ▁from ▁the ▁extended ▁feet . ▁ ▁Status ▁ ▁Many ▁species ▁of ▁pol lin ators , ▁including ▁the ▁cal li ope ▁hum ming bird , ▁have ▁shown ▁decre ases ▁in ▁certain ▁populations . ▁Little ▁information ▁is ▁available ▁on ▁the ▁overall ▁issues ▁that ▁are ▁causing ▁these ▁decl ines ▁but ▁possible ▁thre ats ▁include ▁habitat ▁loss , ▁increased ▁use ▁of ▁p estic ides , ▁and ▁replacement ▁of ▁native ▁plants ▁by ▁non - native ▁plants ▁( although , ▁on ▁the ▁other ▁hand , ▁many ▁hum ming bird s ▁benefit ▁from ▁non - native ▁plants ▁in ▁gard ens ▁that ▁provide ▁additional ▁food ). ▁The ▁restricted ▁winter ing ▁range ▁of ▁cal li ope ▁hum ming bird s ▁makes ▁the ▁species ▁more ▁sus cept ible ▁to ▁natural ▁dis aster s , ▁dise ases , ▁or ▁land ▁use ▁changes ▁that ▁could ▁w ipe ▁out ▁significant ▁port ions ▁of ▁the ▁population . ▁The ▁cal li ope ▁hum ming bird ▁has ▁not ▁been ▁well ▁studied , ▁leaving ▁much ▁of ▁its ▁life ▁history ▁unknown . ▁ ▁References ▁ ▁External ▁links ▁ ▁Cal li ope ▁Hum ming bird ▁– ▁St ell ula ▁cal li ope ▁US GS ▁Pat ux ent ▁Bird ▁Ident ification ▁Info Center ▁Cal li ope ▁Hum ming bird ▁Species ▁Account ▁– ▁Corn ell ▁Lab ▁of ▁Or n ith ology ▁Cal li ope ▁Hum ming bird ▁( S el as ph orus ▁cal li ope ) ▁videos ▁at ▁the ▁Internet