## LSU Historical Dissertations and Theses

1989

Dissertation

#### Degree Name

Doctor of Philosophy (PhD)

#### Department

Forestry, Wildlife, and Fisheries

Robert H. Chabreck

#### Abstract

Stomachs from 706 alligators (Alligator mississippiensis) harvested from a southern Louisiana fresh marsh in 1987 and 1988 were examined for web tags from smaller marked alligators. Alligators 2.73 m TL) were significantly more cannibalistic than smaller alligators (P $<$ 0.0001). Males and females were cannibalized in the same proportion they occurred in the population. Cannibalism mortality appeared to be distributed proportionately among all cohorts in the 0.35-2.12 m TL size classes resulting in a relatively uniform reduction across the group. Cannibalism was found to be an important population regulating mechanism, accounting for an estimated 50.2% of total hatchling mortality and 70.1% of total mortality in age 11 months and older alligators. Male growth rates in both a palustrine marsh (Lacassine National Wildlife Refuge) and estuarine marsh (Rockefeller Refuge) marsh types were greater than female rates (P $<$ 0.0001). Growth rates and weight-length ratios of alligators in estuarine marsh were greater than those of alligators in palustrine marsh (P $<$ 0.0001). Age specific fecundity and survivorship rates of alligators in the palustrine marsh were less than alligators in the estuarine marsh. The home range size and activity pattern of adult female alligators of different reproductive status were compared among seasons of the year. Home range size (P = 0.54) and minimum average daily movement rates (P = 0.85) did not differ between nesting and non-nesting radio-collared females during the summer nesting season. No difference was found between females with and without broods in the two variables during the fall brooding season. Adult radio-collared female alligators ranged over larger areas and had greater daily average daily movement rates during the spring breeding season than during any other season of the year (P $<$ 0.01). Annual home range size of the 15 adult female alligators monitored during the study was 36.2 $\pm$ 42.6 (SD) ha.

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