BULLETIN FLORIDA STATE MUSEUM


rubble bottom. Though the species is confined to this type of habitat
over most of its range, populations in prairie and plains areas, particu-
larly in Missouri, Iowa, and Nebraska, tolerate extreme turbidity
and seasonally warm water provided a rubble or gravel bottom and
a good current are still present. These factors seem more critical
for spawning than clarity of water. Two other fishes, Rhinichthys
cataractae and Hybognathus hankinsoni, which are commonly thought
to be limited to clear, cool waters, are also able to survive under
these same conditions of turbidity and high temperatures.
 N. cornutus is usually found at the head or foot of riffles, most
often the latter, but it tends to avoid the actual riffle except at spawn-
ing time. It likewise avoids still waters, though individuals may
occasionally be found in them, especially if a slight current is present.
 Although this species is generally a stream fish, it is also common
in lakes in the northern part of its range. The apparent geographical
bias probably has several causes. Lakes are relatively few in the
southern part of its range and ecologically unsuitable. The northern
lakes differ in usually having clean, weedless, wave-washed shores
with gravel or rubble bottoms, thus in part duplicating the preferred
stream conditions. The species is not known to spawn in lakes, and
apparently enters them from feeder streams. Strangely neither cor-
nutus nor chrysocephalus occurs, except as strays, in western Lake
Erie where ecological conditions similar to those of inland streams
permit the presence of such usually stream-inhabiting fishes as
Noturus flavus, Etheostoma blennioides, and Etheostoma flabellare.
 Because cornutus is so common and so easily observed, much has
been written about its ecology and life history. Numerous food
study accounts exist, many of which Adams and Hankinson (1928)
reviewed. Largely carnivorous, it apparently prefers aquatic insects
and their larvae. The diet is controlled largely by food availability,
and plant material is not uncommon fare. This shiner usually feeds
at the surface or in the upper water levels, but it may also take food
on the bottom. This versatility in feeding habits probably partly
explains its great success as a species.
 Numerous accounts of its spawning behavior have appeared.
Raney (1940a) reviewed all prior literature and also presented de-
tailed new observations. The species may spawn from mid-May to
mid-July, the time depending mainly on the water temperature; a
minimum of at least 640 F. apparently must be attained before
spawning can occur (Raney 1940a: 4). Although spawning has been
observed in water as warm as 830 F., this is unusual, for spawning is
normally completed before such temperatures are reached.


Vol. 8