Nesting Ecology of Alligators in Louisiana

According to McIlhenny (1935) the alligator, Alligator m'!8Stsstppiensis, with the exception of the crocodile, Crocodylus acutus, of southern Florida, is by far the largest reptile inhabiting the United States. This species is found throughout Louisiana, with the bulk of the population located in the coastal marshes of the state. During the late 1950's concern for the survival of this species arose due primarily to excessive hide hunting. So numerous were these reptiles that old hunters speak of having seen their eyes in the glare of the headlights shining on the bayou waters as thickly as stars overhead. In the spring the bellow of the male was one of the most characteristic sounds of the marshes. In the middle of the 1920's the coastal marshes were beginning to open up primarily for trapping of fur bearing animals. Canals were dug through the remote areas, trapping camps built as strategic intervals, and systematic exploration of the natural resources begun. Fur was trapped in the winter and alligators were hunted during the remained of the year. During the extremely dry years, such as 1925 and 1926, many gators were forced to leave their dens and make new ones wherever they could find water. At this time the marshes were burned and many thousands of alligators were killed by hide hunters. McIlhenny (1935) estimated that from 3 to 3% million were harvested in Louisiana between 1880 and 1933. Today, probably the only remaining sizable population of alligators are located throughout the refuges which are both state and federally owned. Also, large tracts of land which are privately owned support good populations of alligators. Large swamps and marshes that are inpenetrable to man also possess good populations of alligators. Very little is known about the life history of this ancient reptile and in the past management of the alligator was limited to regulating the harvest. In 1963, the season was closed statewide and concentrated efforts were made by the Louisiana Wild Life and Fisheries Commission to re-establish this population. Rockefeller Refuge serves as one of the last strongholds of the alligator in the state and with this in mind the project under report was begun to better enable the Commission to more efficiently re-establish this valuable species. The refuges comprises approximately 85,000 acres of coastal marshland of which 25,000 acres are under the impoundment system of management. These marshes provide excellent nesting habitat for alligators although certain marsh types are preferred over others. However, information was needed on the factors associated with reproduction such as nesting success, nest predation, and habitat preferences before definite plans could be formulated for the management of these reptiles. During the summer of 1964 a study was initiated on the nesting ecology of alligators on Rockefeller Refuge. The objectives of the study were: (1) to determine activities of the female associated with nesting, especially during the incubation period, (2) to determine the nesting temperatures inside and outside the nest, (3) to determine the preferred nesting habitat, nest dimensions, number of eggs present in each nest, and reproductive success, (4) to determine the kind and amount of nest losses on alligator eggs due to predation and other causes.