I024 FRESH-WATER BIOLOGY 



''But the old ones show no fear of the water; I have frequently 

 seen them swimming both under water and on the surface, even 

 where the current was pretty strong, and have always observed 

 them to be perfectly confident and unfrightened at such times." 



Birds 



In cold and temperate regions birds are seasonal, robbing, \isi- 

 tors of the water. Only one-fourth to one-fifth of our entire bird 

 fauna is in any sense aquatic.^ 



The passerine birds are dominant now and of this group none 

 are strictly aquatic. One hundred and twenty-nine of the 215 

 species of birds of Monroe County, Indiana, are passerine. Of 

 these only the red-winged blackbird, the six species of swallows, 

 the water thrushes, and the long-billed marsh wren are, even re- 

 motely, related to the water. Taking all the birds that range in 

 or about the water — for none of them can be said to home in the 

 water — one finds a graduated series, from those more to those 

 less aquatic in their habits. More than this, birds show the most 

 complete series of adaptations to different aquatic zones. 



The swallows must, by courtesy, be mentioned as forming the 

 first of this series of ecological groups. They are never found 

 upon or in the water, but skim over its surface, occasionally just 

 touching it in their search for food. Mosquitoes and other minute 

 aquatic insects are the attraction for them and they are, therefore, 

 very definitely related to the aquatic fauna. They remain in the 

 latitude of the Ohio River from early April to September. 



A second ecological group is formed by the kingfisher, the terns, 

 gulls, and (for fresh waters rarely) the pelicans. The kingfisher, 

 from his perch over a stream, dives into the water beneath him for 

 fishes. He is largely a shore fisher. The terns, gulls, and pelicans 

 dive from an aerial poise into the pelagic region of the lake and 

 secure fishes near the surface. The terns and gulls also alight to 

 pick the refuse floating on the surface for they are scavengers as 



^ Out of 99 birds observed during the summer about one of the northern Indiana 

 lakes, 19 are more or less related to the water. Out of 215 birds observed at all 

 seasons of the year about Bloomington, Indiana, 55 are related to the water. 



