Nocturnal behavior of American Alligator (Alligator mississippiensis) in the wild during the mating season
Abstract. For full text please see Herpetological Bulletin (2010) 111: 4-11.
In the course of 380 hours of nighttime observations of American alligators in the wild in 2006-2009, two previously undescribed forms of social behavior were observed.
The first behavior, provisionally called "courtship gatherings", involves groups of up to 100 adult alligators in Florida, but less than 10 at various locations in the northern part of the species' range. Alligators gather in those groups on most (but not all) nights during the mating season, at locations slightly changing from night to night. They spend 4-8 hours (but not all night) swimming in pairs, courting, chasing each other, and occasionally fighting. Individual animals were observed to attend such gatherings for many nights, arriving and leaving by themselves or in pairs, and sometimes swimming to the sites of gatherings from 2 miles away. Copulations were observed near the gathering sites or after the gatherings, but never directly within. Bellowing choruses were twice as likely to occur on the mornings following nights with gatherings as on the mornings following nights without gatherings.
The second type of behavior is cooperative feeding - or, more precisely, gathering for fishing. Unlike courtship gatherings, cooperative feeding can occur at any time of the day, involves constant feeding activity, and usually has subadults and juveniles present; repertoire and frequencies of observed behaviors differ markedly between these two types of gatherings.
Cooperative feeding has been reported for many species of crocodilians, although never before described in detail. Courtship gatherings are present in both alligator species, at least some caimans, and possibly in the Indian gharial, but not in crocodiles, probably because crocodile males are more territorial during the mating season. The reason this common and conspicuous behavior has never been described in literature is most likely that no studies of nighttime alligator behavior in the wild during the mating season have ever been conducted before.