( So ( ( if ( ( the pair ) ( ( does n't ) mate ) ) ) ( I ( ( could ( use ( my ( male bird ) ) ) ) . ) ) ) )
(ROOT (S (CC So) (SBAR (IN if) (S (NP (DT the) (NN pair)) (VP (VBZ does) (RB n't) (VP (VB mate))))) (NP (PRP I)) (VP (MD could) (VP (VB use) (NP (PRP$ my) (JJ male) (NN bird)))) (. .)))
So if the pair doesn't mate I could use my male bird.
(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.