STUDYING THE HABITS OF FISHES. II 1 5 



governed accordingly. In studying the suckers it is usually necessary to remain 

 very quiet and hidden behind some suitable shelter; but if the suckers happen 

 to frequent the neighborhood of a bridge where there is frequent passing they 

 become gradually used to the presence of human beings, and may then be 

 watched without observing any unusual precautions. The black bass mav be 

 observed only by taking the utmost care not to disturb it, while the common 

 sunfish (Eupomotis gibbosus) may, under most circumstances, be approached 

 without difficulty. 



In addition to the differences between species with reference to the readi- 

 ness with which they become habituated to the observer, there are differences 

 in the same species at different seasons. The areas suitable for the breeding 

 activities of most species are of limited extent. On these areas the individuals 

 of the species congregate at the breeding season, and it is then that they are 

 most readily approached. If in addition to frequenting a particular breeding 

 ground a species is in the habit of building nests, its activities are then centered 

 about areas of still smaller extent, and it becomes proportionately easy to 

 observe them. The breeding season therefore offers the best opportunities for 

 observing the habits of fishes, not only because the fish are then gathered into 

 limited areas, but also because they are easily approached on these areas and 

 readily return to them when frightened away. 



The tie which binds breeding birds to the nest and young has been made 

 use of by Herrick (1902) in his remarkable studies of the "Home Life of Wild 

 Birds." He has sawed off the supporting branch and thereby transferred nests 

 from inaccessible trees to places more convenient for observation. The parent 

 birds after recovering from their brief fright returned to their duties, while he 

 watched them from a tent set up within two or three feet of the nest. He 

 found that this parental instinct which, like a chain, binds the bird to its 

 nest and makes it follow wherever the nest is carried, varies in strength at 

 different times and in different birds. The nest should be moved for purposes 

 of study at that time at which the parental instinct is at its strongest. 



The like is true of fishes. A fresh-water dogfish may be readily frightened 

 from its nest before the eggs are laid in it, but is much less easily frightened 

 after the nest has been filled with eggs or the young fish hatched. The common 

 sunfish becomes so tame when it has eggs in the nest that, as Thoreau (1849) long 

 ago found, one may stand astride of the nest, stroke the fish on the back, and 

 feed it from the hand. One may even lift the fish from the water in the hand, 

 and when it is returned it will resume its parental duties. In like manner Miss 

 Reeves ( 1 907) found of the breeding rainbow darter (Etheosioma coeruleum) : 



They quickly become accustomed to one's presence and are not then disturbed 

 by one's wading among them. I have touched them with my boot tips or stroked 

 them with a small wire without their moving. It is then possible to stand directly 

 over them and even to examine them with a hand lens without in any way modifying 

 their normal behavior. 



