V-D-2 



Joanen, T. 1969. Nesting ecology of alligators in Louisiana. Proceedings 



of the Twenty-Third Annual Conference of the Southeastern Association 



of Game and Fish Commissioners, pp. 141-151. 



Rockefeller Refuge served as one of the last strongholds of the 

 alligator in Louisiana, and with this in mind the project under report 

 was begun to enable the Commission to re-establish this valuable species 

 in a more efficient manner. The refuges comprise 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, and (4) to determine the kind and amount of nest 

 losses on alligator eggs due to predation and other causes. During 

 this study, nests were equipped with Stephens Model F Recorders, 

 Taylor Temperature Recorders, and Short and Manson Hair Hygrographs. 

 These instruments were used to record movement of the female over the 

 nest, nesting temperatures inside the egg cavity, and relative humidity 

 of the egg cavity. Data from the movement recorders indicate alligators 

 pay little attention to their nest after the eggs are deposited. 

 Each nest varied in the number of crossings, with one nest recording 

 as few as 8 visits and one nest as many as 25 visits during the 65-day 

 incubation period. The majority of the 66 visits tallied were recorded 

 in the first, second, third, and ninth weeks of incubation. 



Of the 315 nests followed during the course of the study, 79.7 percent 

 were located in the natural marsh, 13.6 percent in the impounded marsh, 

 and 6.7 percent on the levees. 



It has been assumed that the alligator protects its nest from predators 

 and intruders, but this was not demonstrated during the study. Several 

 nests were destroyed by raccoons while the female was present at the nest 

 site. At the 315 nests examined, only 29 females, or 9.2 percent, made any 

 attempt to protect their nests when the site was visited by persons conducting 

 this study. Weekly checks were made on each nest, and it was found that 

 these 29 alligators were the only permanent residents at the nest site in 

 the early weeks of incubation. As the incubation period progressed, 

 only 24, or 7.6 percent, of the females were seen at the nest on the weekly 

 visits. 



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