Examination of 313 stomachs of k.ingfistLei<&, collected in widely- 

 different sections of the. country, showed that less, than half the. fishes taken 

 were of kinds usually eaten by man, ' "'Crawfishes formed 16 percent of the total 

 food, frogs more than 5 percent, and ^-jater beetles about 4 percent. Because 

 the bird occurs ■ singly or in pairs and is so widely distributed, it is probable 

 that its depredations are comparatively unimportant except at fish hatcheries 

 and on planted streams. At these places appropriate protective measures can 

 often greatly lessen the damage. Furthermore, it should be remembered that 

 many of the fi-shes taken are noted enemies of sporting varieties in. that they 

 feed extensively o'n spawn of the species prized by man, 



•• Great Blue Heron 



Because of its large size and nature of feeding, the great blue heron 

 is both widely knovm and condemned by inland fishermen. In its feeding, the 

 bird is usually solitary, yet at its nesting sites it is distinctly gregarious. 



In its food tendencies the bird' is predominantly a fish-eater, yet 

 among other foods taken in quantity are Small . mammals (especially meadow mice), 

 dragonfly nymphs, viiater beetles, water bugs "and other aquatic insects, craw- 

 fishes, snakes, salamanders, and leeches. Many' items in its diet are species 

 that are predacious upon youn£ fishes or fish spawn. Away from, hatcheries 

 under normal conditions it is certain that the bird consumes far more fishes of 

 species of no value to man than it does of those sought by the angler. Further- 

 more, many of those not utilized in human consumption are' direct enemies of, or 

 competitors with, the valuable food fishes. 



To illustrate, a series of 8 stomachs from a popular trout stream in 

 vjestem Montana (collected in mid-June 1936) — a stream that has been well 

 stocked with Loch Lev en trout in addition to having an abundant supply of 

 native trout — revealed such spawn-eaters as 28 suckers, 15 frogs, 9 sculpins, 

 besides 7 trout, 1 minnow, 1 mouse, , and several large water tigers (Dytiscidae) 

 and dragonfly nymphs (Aoschnidae) , both of which groups of insects prey exten- 

 sively on small fishes. It is obvious that in this series the great blue heron's 

 destruction of large numbers of -vjell-knovi/n fish predators or s'p awn- eaters more 

 than, offsets damage to the trout supply. 



Examination of the stomachs of 189 great blue herons, collected through- 

 out the year from the Atlantic to the Pacific and from Canada to the Gulf of 

 Mexico, disclosed that nongame fishes" of li-ttle or no commerciaij. value made up 

 43,16 percent of the food, while valuable species composed 24,8 percent, and 

 unidentified fish remains S.'^Q percontf Insects, amounting to 8,15 percent, 

 included chiefly aquatic forms, among which the dragonfly nymphs and adults 

 m.ado up the greatest proportion. CraVJfishes formed 6.54 percent of the total 

 food iind other crustaceans 0,91 percent. Amphibians, mainly frogs, and rep- 

 tiles, chiefly snakes and turtles, m.ade up 4,25 percent," xvhile mice and shrev;s 

 comprised 4,66 percent. Miscellaneous invertebrates and vegetable debris 

 formed the remainder, l/'i/hen -not overabundant the bird is unquestionably a 

 natural asset. At fish hatcheries and occasionally on planted small" streams, 

 however, it is known to be destructive. Preventative measures or control, there- 

 fore, are a necessity in- such circumstances, but it should be remembered that 

 herons are protected by Federal law, and permits should obtained when control 

 of the birds is necessary. 



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