( We ( ( ( ( ( know , ) ( for example ) ) , ) ( that ( ( one-forth ( of ( ( the ( bird species ) ) ( on ( the planet ) ) ) ) ) ( have ( ( gone ( ( ( extinct , ) due ) primarily ) ) ( to ( ( human actions ) ( -LRB- ( ( hunting ( and ( habitat destruction ) ) ) -RRB- ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP We)) (VP (VBP know) (, ,) (PP (IN for) (NP (NN example))) (, ,) (SBAR (IN that) (S (NP (NP (NN one-forth)) (PP (IN of) (NP (NP (DT the) (NN bird) (NN species)) (PP (IN on) (NP (DT the) (NN planet)))))) (VP (VBP have) (VP (VBN gone) (ADJP (ADJP (JJ extinct)) (, ,) (ADJP (JJ due)) (ADVP (RB primarily))) (PP (TO to) (NP (NP (JJ human) (NNS actions)) (PRN (-LRB- -LRB-) (NP (NN hunting) (CC and) (NN habitat) (NN destruction)) (-RRB- -RRB-))))))))) (. .)))
We know, for example, that one-forth of the bird species on the planet have gone extinct , due primarily to human actions (hunting and habitat destruction).
(ROOT (S (NP (NNP Human) (NNS actions)) (VP (VBZ is) (ADJP (JJ responsible) (PP (IN for) (NP (NP (DT the) (NN extinction)) (PP (IN of) (NP (NP (NNS hundreds)) (PP (IN of) (NP (NP (NNS species)) (PP (IN of) (NP (NNS birds))))))))))) (. .)))