sentence2_structure: Birds<>pair up<>with the same bird in mating season
sentence1: During the breeding season, mourning doves are monogamous, remaining with the same partner; the Wild Birds Unlimited website states that evidence has been found suggesting that mourning doves also pair up with the same mates for future breeding seasons.
sentence2: Birds pair up with the same bird in mating season.
question: What do birds do in mating season?