Question: What is the purpose of the male Magnificent Frigatebird's large red pouch?
Answer: Only male frigatebirds have gular pouches that turn bright red in the breeding season. At that time, the males inflate these balloon like appendages using them to display to attract a mate.
As far as biologists know this is the only use for the unique structure. Interestingly, at the Marco colony, the frigatebird population is 97% male and in the winter sometimes (especially at sundown) good numbers of frigatebirds can be seen roosting.
This is the start of the breeding season and although they do not nest in south Florida, many of the males will collect around a lone female and display to her. From a distance, the mangrove islands look as though they are all in bloom.