44 AN ECONOMIC STUDY OF FIELD MICE. 



The most common Old- World representative of the genus is Buteo 

 huteo, the common buzzard of England, and popularly known in 

 Germany as the mouse buzzard (Mausehussard) . That the last name 

 is well deserved, is shown from the researches of Dr. G. Korig, of 

 Berlin, who in 784 stomachs of this species found no less than 1,124 

 rodents, of which 1,057 were the common field mouse (M. arvalis). a 



Two prominent species of rough-legged hawks (Archihuteo) occur 

 in America. Both are winter sojourners with us. The northern form, 

 the common rough-leg (Archihuteo J ago pus sancti-johannis) , sum- 

 mers north of the United States. The ferruginous rough-leg {A. fer- 

 rugineus), commonly known as the squirrel hawk, nests extensively 

 in the Western States, but is more common there in winter. Both 

 species are large and may be easily distinguished by the feathering of 

 the legs, which extends to the base of the toes. Doctor Fisher ex- 

 amined 50 stomachs, all but 1 being of the common rough-leg. Of 

 these. 40 contained mice only: 5, other mammals; 1, insects and a 

 lizard ; and 4 were empty. Of the 40 containing mice, 28 had meadow 

 mice only, the number varying from 1 to 8 and the average being 

 more than 3 to each hawk. These are winter records. In summer 

 the birds doubtless are largely insectivorous. It is certain that the 

 rough-legs do not often molest wild birds or domestic fowls. 



The researches of Doctor Korig make an equally favorable show- 

 ing for the Old World rough-legged hawk (Archihuteo lag opus lago- 

 pus). He examined 250 stomachs of that species and found remains 

 of 879 rodents, mostly field mice. Xinety-four per cent of the birds 

 examined by him had eaten injurious rodents. 6 



The true falcons (genus Falco) of Xorth America comprise 17 

 species and subspecies, of which 3 are accidental A'isitors from abroad, 

 and several others, notably the gyrf alcons, are exceedingly rare within 

 the United States. The various falcons differ much in size, but all 

 are strong and swift of wing. The larger species destroy poultry and 

 game, while the smaller kinds prey upon small birds and insects. All 

 feed to some extent upon mice. The most common species are the 

 duck hawk (Falco peregrlnus anatum) , the prairie falcon (Falco 

 mexicanus) , the pigeon hawk (Falco columharius) , and the sparrow 

 hawk (Falco spar verias). 



The duck hawk is a rather large falcon, and, as its name implies, 

 preys much upon waterfowl. It destroys also game birds, domestic 

 fowls, .pigeons, and small birds. Although it feeds to some extent 

 also upon insects and mice, the habits of the species, on the whole, 

 do not commend it to the protection of farmers and sportsmen. 



o Arb. Biol. Abteilung fur Land- nnd Forstwirtschaft. IV Band. 1 Heft, 

 p. 64, 1903. 



6 Arb. Biol. Abteilnng fur Land- und Forstwirtschaft, IV Band, 1 Heft, p. 74, 

 1903. 



