Although they don’t perform ceremonies and have receptions, scientists equate “marrying” with an animal being monogamous, or having only one mate. It is estimated that 90 percent of bird species are monogamous—that is, one male mates with one female to produce offspring. Some of these pair bonds may extend beyond a single mating season, so this could be considered a form of “marriage.” The type of pair bonds a species will form is dependent on their ecological niche and is heavily influenced by the needs of their offspring. Altricial offspring require large amounts of parental care for survival (like humans) and demand the efforts of two parents; therefore, they are more likely to be found in monogamous species.