Carolina Madtom 
77 
Cans or bottles with small openings are probably favored as nest 
sites by large males because they are easy to protect. Head width in 
eight reproductively mature males ranged from 15.1 to 29.0 mm (x = 
22.4) and head depth ranged from 7.8 to 16.0 mm (x = 12.3). Pop-top 
beer and soda can openings ranged from 18.5 to 28.0 mm in length (x = 
23.7) and from 13.0 to 20.0 mm in width (x = 16.2). Thus, there is little 
room to spare at the opening of a can once a male is inside. Guardian 
males with their swollen heads generally face the opening of the 
container, presumably blocking the entry of most potential predators. It 
is not known whether a male enters a can with his head muscles and lips 
already swollen or if these changes take place after he has selected his 
nest site. 
During May we found no instances of syntopic species of Noturus 
nesting in areas with N. furiosus. Both N. gyrinus and N. insignis were 
uncommon or not found in N. furiosus nesting habitat. Crayfishes, 
juvenile madtoms, A. rostrata, and Necturus lexvisi may compete for 
nest or hiding sites with N. furiosus. The waterdog and N. furiosus are 
sympatric, and one nest of the former has been found under a flat rock 
(Ashton and Braswell 1979). Although we did not find any N. furiosus 
nests under rocks, the species may use such sites at least occasionally, 
especially since close relatives of the species have been found to do so 
(see Burr and Mayden 1982a, 1984). Like other ictalurid catfishes, N. 
furiosus is a member of the speleophil reproductive guild as defined by 
Balon (1975). 
Clearly, N. furiosus has taken advantage of human litter as potential 
nest sites, but the presence of several adults in reproductive condition 
under mussel shells (mostly Elliptio complanata ) and bark indicates that 
before the advent of modern man these were perhaps the only form of 
adequate-sized cover available. Our survey work indicates that the 
number of artificial nest sites (i.e., cans and bottles) far exceeds the 
number of adequate-sized natural sites in the streams we intensively 
sampled. 
Larval Development. As in other species of Noturus, embryos 
adhere to each other in a mass, but not to other surfaces. Chorion 
diameters of 45 pre-hatchling embryos ranged from 3.8 to 4.4 mm (x = 
3.9 mm). Yolk sacs of developing embryos were cream to light yellow, 
similar to yolks of N. flavus (Walsh and Burr 1985), but in contrast to 
the darker yellow or nearly orange yolks in N. albater (Mayden et al. 
1980), N. exilis (Mayden and Burr 1981), N. miurus (Burr and Mayden 
1982a), and N. nocturnus (Burr and Mayden 1982b). Yolk diameters 
averaged 3.2 mm (range = 2.5 to 4.0; N = 45). 
At about 1 day post-hatching, larvae ranged in TL from 9.1 to 10.0 
mm (x = 9.5; N = 16), had well-developed maxillary and mandibular 
