▁Life ▁cycle ▁ ▁Life ▁history ▁aspects ▁of ▁this ▁species , ▁including ▁its ▁re product ive ▁behavior , ▁are ▁unknown . ▁ ▁Conserv ation ▁ ▁The ▁number ▁of ▁c aves n ails ▁has ▁significantly ▁decre ased ▁over ▁the ▁past ▁few ▁dec ades , ▁from ▁an ▁estimated ▁ 1 5 , 1 1 8 ▁in ▁ 1 9 7 3 , ▁to ▁the ▁point ▁where ▁only ▁one ▁individual ▁was ▁found ▁within ▁the ▁survey ▁areas ▁during ▁January ▁ 1 1 , ▁ 2 0 0 1 ▁and ▁April ▁ 2 2 , ▁ 2 0 0 3 . ▁A ▁small ▁population ▁containing ▁approximately ▁ 4 0 ▁individuals ▁does ▁exist ▁however ▁in ▁a ▁small ▁area ▁up stream ▁from ▁the ▁part ▁of ▁the ▁cre ek ▁that ▁is ▁regularly ▁survey ed . ▁Based ▁on ▁the ▁decl ine ▁of ▁the ▁T umb ling ▁Creek ▁c aves n ail , ▁it ▁is ▁listed ▁as ▁end anger ed ▁at ▁United ▁States ▁Fish ▁and ▁Wild life ▁Service ▁list ▁of ▁end anger ed ▁species ▁since ▁August ▁ 1 4 , ▁ 2 0 0 2 . ▁ ▁Although ▁the ▁primary ▁limit ing ▁factor ▁of ▁the ▁population ▁appears ▁to ▁be ▁decre ased ▁water ▁quality , ▁due ▁to ▁increased ▁er os ion ▁and ▁water ▁poll ution ▁in ▁the ▁cave ’ s ▁re charge ▁area , ▁scientific ▁research ▁is ▁needed ▁to ▁confirm ▁this ▁hypothesis . ▁ ▁See ▁also ▁ ▁Ant rob ia ▁bre wer i ▁is ▁a ▁syn onym ▁( orth . ▁error ▁at ▁ 2 0 1 0 ▁IU CN ▁Red ▁List ) ▁of ▁An tr