VALUE OF BIRDS TO MAN. 79 
Enough is known, however, to show that they have some 
beneficial habits, as well as some injurious ones; but they 
constitute a very potential force for harm, on account of their 
great fecundity. I do not know how many young our com- 
mon species can produce ina year, but two female European 
field mice kept in captivity gave birth to thirty-six young 
within five months. The tally was ended by’the escape of 
one of the pair, else there probably would have been re- 
corded a still larger number. The interval between the birth 
of one litter of young and that of the next was only from 
twenty-four to twenty-nine days. This shows the danger 
that might easily arise from the unchecked increase of a 
creature which, feeding upon both crops and trees, is capable 
of unmeasured devastation. It also shows the folly of ex- 
tirpating those Hawks and Owls which are known to feed 
largely on field mice, for they constitute the only natural 
force, that can quickly assemble at a threatened point, for 
the reduction of these pests. 
The number of small rodents eaten by the rapacious birds 
is almost as remarkable in proportion to their size as is the 
number of insects taken by smaller birds. Lord Lilford says 
that he has seen a pair of Barn Owls bring food to their 
young no less than seventeen times within half an hour, 
and that he has fed nine mice in succession to a young Barn 
Owl two-thirds grown.! During the summer of 1890 a pair 
of Barn Owls occupied a tower of the Smithsonian building 
at Washington. It is the habit of Owls to regurgitate the 
indigestible portions of their food. Dr. A. K. Fisher found 
the floor strewn with pellets of bones and fur which these 
birds and their young had thrown up. An examination of 
two hundred of the pellets gave a total of four hundred and 
fifty-four skulls: two hundred and twenty-five of these were 
meadow mice; two, pine mice; one hundred and seventy- 
nine, house mice ; twenty, rats; six, jumping mice ; twenty, 
shrews; one, a star-nosed mole; and one, a Vesper Spar- 
row.? In my examinations of. the stomachs and pellets of 
1 An article on the Barn Owl, by W. B. Tegetmeier. Field, Vol. LXXV, 
No. 1956, June 21, 1890, p. 906. 
? The Hawks and Owls of the United States, by Dr. A. K. Fisher. United 
States Department of Agriculture, 1893. ‘ 
