Field and Laboratory Observations on 



Microhabitat Selection, Movements, and Home 



Range of Necturus lewisi (Brimley) 



Ray E. Ashton, Jr. ' 



North Carolina State Museum of Natural History, 

 P. O. Box 27647, Raleigh, North Carolina 27611 



ABSTRACT. — Movements, microhabitat selection and home ranges 

 of 20 adult and 5 juvenile Necturus lewisi were studied in the Little 

 River, Wake and Johnston counties, North Carolina, from November 

 1977 to May 1981. They were tagged with 6 ° Co wires and monitored 

 biweekly. Necturus lewisi occupied home ranges (x = 17.37m 2 for 

 females and 73.25m 2 for males). Five juveniles tagged and released 

 remained within 134 m 2 over an eight-month period. The primary 

 microhabitat used by both juveniles and adults was loose granite 

 boulders on sand-gravel substrate. The next most important microhab- 

 itat was under bedrock embedded in stream banks. Leaf beds, reported 

 to be important habitat for N. lewisi, rarely were visited by the anim- 

 als. Microhabitat use varied with season and temperature range. 

 Trends indicated that dissolved oxygen, flow rate, and precipitation 

 influenced overall movement and microhabitat selection. 



Retreat areas were maintained by juveniles and adults in the 

 laboratory, and similar behavior was observed in the field. The animals 

 moved sand and gravel by shoveling with the snout and transporting it 

 by mouth. Retreat areas were defended by adults, who displayed dis- 

 tinct threats and occasional attacks on intruders of either sex. Females 

 permitted males to cohabit their retreats during late winter and early 

 spring, when controlled laboratory temperatures were 8 to 14 degrees 

 C. Larvae and juvenile N. lewisi were not attacked and were permitted 

 to enter retreat areas unmolested. Both visual and olfactory cues were 

 used to locate and capture food. The primary method of feeding was 

 to sit at the mouth of the retreat where prey could be detected when it 

 came near. The animals commonly stalked prey at night. Courtship 

 was observed and was similar to that described for N. maculosus. 



INTRODUCTION 



Few studies have been published on Necturus behavior, move- 

 ments, and microhabitat use. Eycleshymer (1906), Smith (191 1), Bishop 

 (1926, 1941), and Harris (1961) reported on these topics as observed in 

 northern populations of Necturus maculosus. Cagle (1954), Shoop 

 (1965), and Shoop and Gunning (1967) made detailed studies of N. 



1 Present address: International Expeditions, 1776 Independence Court, Birm- 

 ingham, Alabama 35216 



Brimleyana No. 10:83-106. February 1985. 83 



