116 William S. Birkhead and Charles R. Bennett 



Table 4. Estimated lengths of alligators sighted in Dutchman Creek estuary 

 from September 1971 through August 1976. 









Length 













<1 m 



1-2 m 





>2m 



Undetermined 



Totals 



1971-72 





7 







8 





15 



1972-73 





10 





2 



3 





15 



1973-74 



1 



17 







2 





20 



1974-75 



2 



13 







6 





21 



1975-76 





7 





3 



6 





16 



Totals 



3 



54 





5 



25 



87 



fish and shellfish are relatively high. In keeping with this hypothesis, the 

 alligators that we observed in the lower reaches of the Dutchman Creek 

 estuary in the first year of study (1971-72) may have been only tempor- 

 ary inhabitants whose presence was due to a plentiful food supply. 



Another reason for the distributional shift may be related to nest- 

 ing requirements. Joanen (1969) found that most alligators on the 

 Rockefeller Refuge in coastal Louisiana nested in natural marsh consist- 

 ing primarily of wiregrass, Spartina patens. Salinities in these marshes 

 averaged 3.8 ppt. No nests were transected in the more saline marsh 

 type (Joanen et al. 1971). When questioned as to where estuarine- 

 inhabiting alligators in the vicinity of Southport nested, long-time resi- 

 dents invariably stated that nesting occurred along the upper reaches of 

 estuarine tributaries in a narrow zone characterized by freshwater marsh 

 vegetation. Because this type of habitat was not sampled in our study in 

 the Dutchman Creek estuary, such statements could not be verified for 

 North Carolina. This kind of marsh, although limited in extent, would 

 seem to be a more favorable nesting habitat than the salt marsh proper, 

 where the danger of inundation during storm tides would undoubtedly 

 be greater. In support of this belief is the observation that nearly all 

 juvenile (< 1 m) alligators seen in the vicinity of Southport were in 

 freshwater habitats. At one locality in particular, one of us (WSB) 

 repeatedly saw several alligators as small as 0.5 m long in a shallow 

 freshwater impoundment created by diking off approximately 10 ha of 

 saltmarsh adjacent to a tidal creek about 6 km north-northeast of 

 Southport. 



The number of alligators sighted in the Dutchman Creek estuary 

 during the 5-year study remained relatively constant from year to year 

 despite a major alteration in their habitat. However, continued survival 

 of individuals now inhabiting the freshwater drainage canal could be 

 jeopardized because this canal has made their habitat more accessible to 

 humans. 



