( ( ( ( Living off ) ( the fish ) ) ( , ( and ( ( concentrated ( in ( great numbers ) ) ) ( by ( ( the ( small areas ) ) ( of ( available ( nesting sites ) ) ) ) ) ) ) ) ) ( , ( ( ( ( ( ( literally millions ) ( of seabirds ) ) , ) ( ( each excreting ) ( about ( ( 20 grams ) ( of ( dung ( a day ) ) ) ) ) ) ) , ) ( ( can ( generate ( ( massive amounts ) ( of guano ) ) ) ) . ) ) ) )
(ROOT (S (UCP (VP (VBG Living) (PRT (RP off)) (NP (DT the) (NN fish))) (, ,) (CC and) (ADJP (JJ concentrated) (PP (IN in) (NP (JJ great) (NNS numbers))) (PP (IN by) (NP (NP (DT the) (JJ small) (NNS areas)) (PP (IN of) (NP (JJ available) (JJ nesting) (NNS sites))))))) (, ,) (NP (NP (NP (RB literally) (NNS millions)) (PP (IN of) (NP (NNS seabirds)))) (, ,) (NP (NP (DT each) (NN excreting)) (PP (IN about) (NP (NP (CD 20) (NNS grams)) (PP (IN of) (NP (NP (NN dung)) (NP (DT a) (NN day))))))) (, ,)) (VP (MD can) (VP (VB generate) (NP (NP (JJ massive) (NNS amounts)) (PP (IN of) (NP (NN guano)))))) (. .)))
Living off the fish, and concentrated in great numbers by the small areas of available nesting sites, literally millions of seabirds, each excreting about 20 grams of dung a day, can generate massive amounts of guano.
(ROOT (S (NP (NP (DT The) (NN amount)) (PP (IN of) (NP (NP (NN food)) (ADJP (JJ available) (PP (IN in) (NP (DT the) (NN area))))))) (ADVP (RB best)) (VP (VBZ determines) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NNS wolves)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (VP (VB live) (PP (IN in) (NP (DT an) (NN area))))))))))) (. .)))