8 4 1 ▁from ▁a ▁spec imen ▁collected ▁on ▁Santiago ▁Island ▁in ▁the ▁Gal á pag os . ▁The ▁species ▁is ▁sometimes ▁placed ▁in ▁the ▁genus ▁Lar us . ▁It ▁is ▁possibly ▁closely ▁related ▁to ▁the ▁la ughing ▁g ull . ▁ ▁Description ▁The ▁la va ▁g ull ▁is ▁a ▁distinct ive ▁g ull , ▁▁ ▁and ▁we igh s ▁. ▁The ▁adult ▁pl um age ▁consists ▁of ▁a ▁so oty ▁brown ▁to ▁black ▁head , ▁which ▁unlike ▁other ▁dark ▁h ood ed ▁g ull s ▁doesn ' t ▁vary ▁by ▁season . ▁The ▁wings ▁are ▁dark ▁gray ▁with ▁a ▁contrast ing ▁white ▁line ▁on ▁the ▁leading ▁edge , ▁thought ▁to ▁play ▁a ▁function ▁in ▁displays ▁and ▁cam ou fl age . ▁Its ▁dark ▁gray ▁body ▁contrast s ▁with ▁a ▁pal er ▁gray ▁bel ly . ▁The ▁upp ert ail ▁is ▁white ▁and ▁grey ▁lower ▁down . ▁The ▁bill ▁and ▁legs ▁are ▁black , ▁and ▁the ▁inside ▁of ▁the ▁mouth ▁is ▁scar let . ▁ ▁It ▁has ▁white ▁upper ▁and ▁lower ▁e y eb rows , ▁with ▁red ▁l ids . ▁Im m ature ▁g ull s ▁are ▁generally ▁dark ▁brown . ▁ ▁Distribution ▁The ▁entire ▁population ▁lives ▁on ▁the ▁Gal ap ag os ▁Islands ▁where ▁it ▁is ▁found ▁pre domin antly ▁on ▁the ▁islands ▁of ▁Santa ▁Cruz , ▁Isabel a , ▁San ▁Crist ob al ▁and ▁Gen ov esa . ▁Pre viously ▁its ▁population ▁was ▁estimated ▁at ▁ 3 0 0 – 4 0 0 ▁pairs ; ▁this ▁estimate ▁was ▁re vised