56 THE IMPOETANCE OF BIRD LIFE 



birds. Herons are mainly responsible, crawfish 

 forming a large part of the food both of the grown 

 birds and of their young. 



Although crawfish destroy a large number of 

 young fish and attack the roots of corn and 

 cotton plants, for which ravages alone they 

 should be condemned, their chief guilt lies in the 

 destruction of levees and dikes. These little 

 crustaceans have inflicted incalculable damage 

 upon the levees of the lower Mississippi. Many 

 serious floods have been the result of their fond- 

 ness for burrowing through mud to the source 

 of water. A dike honeycombed with crawfish- 

 tunnels is no longer safe. Within the last year 

 thousands of dollars have been expended in New 

 Jersey upon a canal whose walls have been under- 

 mined by the persistent creatures. Other thou- 

 sands of dollars are now to be expended in ex- 

 terminating the crawfish. 



Owing to the former feather trade, herons of 

 almost every sort have suffered a great reduction 

 of numbers in the United States. There are 

 living to-day only a tiny fraction of 1 per cent, 

 of what there were seventy years ago. The spe- 

 cies which mainly inhabit fresh water areas are 

 particularly fond of crawfish, and in former days, 

 in addition to the preservation of levees, thus 

 saved to the Southern planters many hundreds 

 of thousands of dollars' worth of crops. Since 

 the destruction of the birds, however, immense 



