N. lewisi Habitats and Behavior 93 



RESULTS 



Movements and Home Range of Adults 



Of nine adult N. lewisi tagged in the first year, five were located 

 frequently enough (80% of all attempts) to permit measurement of home 

 range. However, even the tagged animals that were not located this fre- 

 quently appeared to move within a home range pattern. The size of the 

 ed by calculating the area within the outermost points of movement and 

 eterminwithin which 95 percent or more of all movements took place 

 (Table 5). Animals monitored in the second year, which were released 

 within a 25 m 2 area, showed that home ranges overlapped regardless of 

 sex or season. Throughout the year all males made greater individual 

 movements (x=75.4 m) than females (x=17.5 m). Females displayed a 

 mean home range of 17.37 m 2 while males had significantly larger home 

 ranges, x=73.25 m 2 (Table 5). 



Table 5. Home range and movements by adult Necturus lewisi. 



Specimen 





Home 





Movements 





No. 



Sex 



range (m 2 ) 



%0-lm Max. 



X 



1 



9 



18.75 



82 



85 



4.10 



2 



8 



84.75 



62 



425 



100.00 



3 



9 



16.00 



53 



250 



27.00 



4 



e 



90.00 



88 



210 



86.60 



5 



8 



49.00 



41 



185 



63.80 



Each home range contained bank areas with animal burrows or 

 rock overhangs, large flat rocks over a sand-gravel substrate, and slack 

 water areas where leaves and other debris formed detritus mats during 

 the fall and winter. Water depths ranged from 15 to 160 cm (x=73 cm) 

 (Table 6). We attempted to determine if movements of all animals 

 changed with environmental factors such as rainfall, barometric pres- 

 sure, moon phase, and air temperature. Seventy-two percent of all adult 

 movements took place within 24 hours after a rainfall of 9 mm or more. 

 Movements declined, however, when rainfall exceeded 40 mm. When 

 stream level increased by more than 15 cm, little movement was 

 observed unless the greater depth was maintained for more than 7 days. 

 In any season there was a 64 percent increase in overall movements as 

 barometric pressure fell or remained below 29.9 mm. Movements 

 increased when moon phase changed from full to dark. Overall move- 

 ments increased during the spring and fall and declined during the win- 

 ter and summer. 



Movements correlated with overall stream and microhabitat tem- 

 perature changes. Carbon dioxide levels and pH remained relatively 



