drainage. Draining marshes to create pastures for cattle 

 reduces the habitat available for ducks (Chabreck et al. 

 1974b), however, habitat conditions are often improved 

 for geese (Chabreck 1968a). 



5.4 AMPHIBIANS AND REPTILES 



5.4.1 AMERICAN ALLIGATOR (Alligator missis- 

 sipiensis) 



McNease and Joanen (1974) found immature alli- 

 gators 1 to 2 m (3 to 6 ft) long on Rockefeller Refuge 

 to be consistently more active than adults. Longest dai- 

 ly movements, up to 2.6 km (1.6 mi), occurred in 

 spring for both males and females. Minimum activity 

 occurred in autumn and winter, although immature 

 animals moved about during winter warm spells. 



Greatest movement of adult females occurs in the 

 spring (April and May), in deep water areas (Joanen 

 and McNease 1970). Average minimum size of the 

 home range during spring for three females was 3.2 ha 

 (7.8 a). 



Adult males actively move about during all seasons 

 except winter, making good use of the network of 

 canals and bayous that are common in the marshes of 

 the Chenier Plain. The minimum daily movements for 

 14 individuals for spring, summer, and autumn ave- 

 raged 735 m (2,411 ft) (Joanen and McNease 1972a). 

 The longest daily movement recorded was 8.5 km 

 (5.2 mi). Largest seasonal ranges were recorded during 

 the summer. During the winter, animals spend the ma- 

 jority of the time in marshes. 



With the possible exception of some portions of 

 the State of Florida, the Chenier Plain supports the 

 highest concentration of American alligator within a 

 10-state region, and the population is still increasing. 



Alligator densities vary from one marsh habitat to 

 another. Density estimates for fresh, intermediate, and 

 brackish marsh habitats in Cameron and Vermilion Pa- 

 rishes were 1 animal per 2 ha (5 a), 1 animal per 3.2 ha 

 (8 a), and 1 animal per 8.1 ha (20 a), respectively (Ni- 

 chols et al. 1976). Salt marsh habitat is not preferred 

 by alligators; Chabreck (1971a) reported that small alli- 

 gators found in salt marsh were weak and consumed 

 less food than those from freshwater areas. Impounded 

 and drained wetlands are also of limited value to alliga- 

 tors (Palmisano et al. 1973). 



The alligator population is segregated to some de- 

 gree. Chabreck (1965, 1966a) found that young alliga- 

 tors that hatched in areas of dense vegetation remained 

 near the nest and did not depart from the mother's 

 den until the spring of their second year. Those reared 

 in bank dens along waterways dispersed in the spring of 

 their first year. McNease and Joanen (1974) reported 

 that immature females preferred natural marsh areas 

 throughout the year, but they also used flooded im- 

 poundments during the spring. Deep water areas provi- 

 ded by canals and bayous were preferred in summer, 

 autumn, and winter. Immature males preferred im- 

 pounded areas in spring, but used deep water areas in 

 summer and autumn. The intermediate marsh habitat 



was preferred by both sexes of immature alligators in 

 this study. Througliout the summer and autumn, 

 nesting females remained in the vicinity of their nest 

 and den sites, which are often located some distance 

 from deep water areas. Joanen and McNease (1970) re- 

 ported that females with well-established marsh dens 

 wintered in them, but spent more time in bayous, canals 

 and lakes during the spring. Adult males preferred open 

 waters and ventured into dense marshes only during 

 the wintering season, except for temporary visits to 

 the dens of adult females during the breeding season in 

 May. 



Alligators are opportunistic carnivores. They will 

 take whatever they can catch and swallow. Fogarty and 

 Albury (1968) reported that young Florida alligators 

 fed heavily on one species of snail. A food habit study 

 by Giles and Childs (1949) on Sabine National Wildlife 

 Refuge showed that crustaceans were the most impor- 

 tant food source for immature alligators. Chabreck 

 (1971a) found the major freshwater food of young alli- 

 gators measuring 0.9 to 1.7 m (2.9 to 5.6 ft) in length 

 was crayfish. Alligators from more saline habitats fed 

 heavily on blue crabs. Mcllhenny (1934) reported 

 herons, turtles, gar, and snakes, in that order of abun- 

 dance, in the stomachs of five adult alligators from 

 Avery Island in southwestern Louisiana. Valentine et 

 al. (1972) found crustaceans and fishes to be the most 

 important food source for alligators of all sizes. The re- 

 cent abundance of nutria in the Chenier Plain region 

 probably has provided an additional source of high- 

 quality food for large alligators. 



Some game birds are also eaten by alligators. 

 Valentine et al. (1972) reported mottled ducks, coots, 

 and clapper rails in stomach contents. Kellog (1929) 

 and Mcllhenny (1939) presented evidence of predation 

 on youngandadult ducks. Chabreck and Dupuie (1976) 

 reported predation by adult alligators on Canada goose 

 nests. 



Water is one of the most important requirements 

 for successful reproduction by alligators. Observations 

 made by Joanen and McNease (1971) on Rockefeller 

 Refuge suggested that deep open-water areas were 

 necessary for courtship activities during early April to 

 early June. Nesting occurred with increasing marsh 

 water levels (Joanen and McNease 1975). Marshes with 

 water salinities of less than 10%o are preferred nesting 

 areas (Chabreck 1971b). 



Temperature is another important factor in alliga- 

 tor reproduction. Joanen (1969) reported that the 

 greater the average temperature for March, April, and 

 May, the earlier the onset of nesting. 



In the past, the most effective management prac- 

 tice has been to restrict the kill of alligators. Protection 

 is still an important management strategy, but there are 

 other ways a land manager may enhance an alligator 

 population (Chabreck 1971b). The maintenance of 

 open water areas during the spring breeding season will 

 provide courtship areas and increase reproduction 

 (Joanen and McNease 1970, 1972a, 1975). Impound- 

 ments are used by immature alligators until late spring. 

 Drawdowns should coincide with the exit of alliga- 

 tors from these areas, beginning no earlier than mid- 

 May. 



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