( ( Some birds ) ( ( ( ( are polygamous ) and ) ( take ( ( ( more ( than one ) ) mate ) ( in ( a season ) ) ) ) ) . ) )
(ROOT (S (NP (DT Some) (NNS birds)) (VP (VP (VBP are) (ADJP (JJ polygamous))) (CC and) (VP (VBP take) (NP (NP (QP (JJR more) (IN than) (CD one)) (NN mate)) (PP (IN in) (NP (DT a) (NN season)))))) (. .)))
Some birds are polygamous and take more than one mate in a season.
(ROOT (S (NP (NNP Birds)) (VP (VB pair) (PRT (RP up)) (PP (IN with) (NP (NP (DT the) (JJ same) (NN bird)) (PP (IN in) (NP (NN mating) (NN season)))))) (. .)))
Birds pair up with the same bird in mating season.