HABITS OF YELLOW PERCH. 333 
Perch eaten, 
Length of 
Date, tl picketel ) 
millimeters). Size 
Number. (millimeters), 
- 
a 
B= 
HHO 
‘oO 
a 
The remains of perch have also been found in largemouth black bass (Micropterus 
salmoides) caught in Lake Mendota. Dogfishes (Amia calva) were often caught in gill 
nets in shallow water, and in many cases they were near perch which had been previously 
captured in the net. Such occurrences indicate that dogfishes may feed upon perch, 
but the authors have never found them in the alimentary canal. The gar (Lepisosteus 
osseus), doubtless, also feeds on young perch. Hankinson (1908) found pickerel feeding 
on perch and also mentions an 8-inch perch as occurring in the wall-eyed pike (Stizos- 
tedion vitreum). Forbes and Richardson (1908) state that 75 per cent of the food of 
the lota (Lota maculosa) is made up of perch. Reighard (1915) reports perch feeding 
on each other. 
Besides finny enemies, perch are probably often beset by other predators; for 
instance, water snakes, garter snakes, and bullfrogs may catch the young alongshore. 
Turtles often eat perch caught in nets, and probably feed upon them when they have a 
chance under natural conditions. 
A. R. Cahn has furnished observations on birds which eat perch. In Wisconsin he 
has found the following feeding on perch: Herring gull, common tern, black tern, Ameri- 
can merganser, red-breasted merganser, great blue heron, green heron, black-crowned 
night heron, loon, horned grebe. He states that the following also probably eat perch: 
Double-crested cormorant, white pelican, other species of gulls and grebes, and the bald 
eagle. Fisher (1893, p. 32) reports the fishhawk as feeding on perch; Eaton (1910, 
p. 137) mentions the kingfisher. The senior writer on June 10, 1916, saw a crow pick a 
crappie (Pomoxis sparoides) from the surface of Lake Wingra. Though the fish in this 
instance struggled actively and finally escaped, the crow may at times be more successful 
in its aquatic forays and capture fishes from the water. Probably such carnivorous 
mammals as the otter and mink at times capture perch. 
Among the predatory animals mentioned the only ones which commonly follow the 
perch into deep water are the pickerel (Reighard, 1915) and the lota. ‘The latter does 
not occur in either of the lakes discussed in this paper but is important in the Great 
Lakes and some other smaller bodies of water. The majority of the perch in Lake 
Mendota are therefore free from attack by predacious enemies during most of the year, 
except for an occasional pickerel. 
PARASITES. 
While the routine weekly examinations of perch were made primarily for the 
purpose of ascertaining the nature of the food, after March, 1915, a careful record was 
kept of the presence of parasites. This record is doubtless incomplete; the numbers are 
too small rather than too large. For example, many of the intestinal distomes were 
doubtless overlooked, because the food was stripped from the intestines, and they may 
