( But ( ( in ( areas ( where ( ( few humans ) live ) ) ) ) ( , ( ( their numbers ) ( ( have ( grown ( due ( to ( ( an increase ) ( in ( humans ( hunting ( their predators ) ) ) ) ) ) ) ) ) . ) ) ) ) )
(ROOT (S (CC But) (PP (IN in) (NP (NP (NNS areas)) (SBAR (WHADVP (WRB where)) (S (NP (JJ few) (NNS humans)) (VP (VBP live)))))) (, ,) (NP (PRP$ their) (NNS numbers)) (VP (VBP have) (VP (VBN grown) (PP (JJ due) (TO to) (NP (NP (DT an) (NN increase)) (PP (IN in) (NP (NP (NNS humans)) (VP (VBG hunting) (NP (PRP$ their) (NNS predators))))))))) (. .)))
But in areas where few humans live, their numbers have grown due to an increase in humans hunting their predators.
(ROOT (S (NP (DT A) (JJR fewer) (NNS predators)) (VP (VBZ is) (ADJP (RBS most) (JJ likely) (S (VP (TO to) (VP (VB cause) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NNS rabbits)) (VP (VBG living) (PP (IN in) (NP (DT an) (NN area))) (S (VP (TO to) (VP (VB increase))))))))))))) (. .)))
A fewer predators is most likely to cause the number of rabbits living in an area to increase.