2 
A little study of the historical side of the question will show 
how the answer is gradually being evolved. We may leave out of 
consideration the earlier works on ornithology altogether, and we 
shall find the germ of the idea in what is perhaps the greatest 
work on the subject ever written—the “ Naturgeschichte der Vogel 
Deutschland’s ” of the two Naumanns. Here, although, of course, 
the execution is imperfect, we find a serious attempt made to give 
a succinct account of the facts known as to the food of each bird, 
and its useful and harmful attributes are set forth side by side. 
Moreover, in the great majority of cases these observations are not 
merely statements copied from previous writers, but the actual 
results of first-hand investigation and dissection. The works of 
Macgillivray (1837-52) and Yarrell (1st Ed., 1839-43) contain 
much information of a desultory nature, but a word of praise must 
be awarded to William Thompson, the author of the “ Natural 
History of Ireland: Birds ” (1849-51), who includes in this valuable 
book the results of the careful examination of the stomachs of many 
birds shot by him. A further step in the right direction was made 
by Elorent Prevost (1864), who introduced the system of tabulating 
a bird’s diet under the heads of the different months. It is obvious 
that many birds must be forced to vary their food according to the 
exigencies of the season, and a bird which maybe actively injurious 
for a short time in the spring or at harvest time, may atone for its 
shortcomings by services rendered during the rest of the year. 
Two papers compiled by Mr. E. Norgate (“ Zool.,” 1881, p. 313, 
410) call for some notice, as in addition to notes collected from the 
works of other writers, they also contain the author’s own obser¬ 
vations on several of our native birds, and it is almost unnecessary 
to say that much fresh material is incorporated in the 4th edition of 
Yarrell’s “ British Birds ” (1871-85), which is for practical purposes 
an entirelv new work.* 
It has been shown that the first attempt to deal systematically 
with this subject was made by the two Naumanns; it was reserved 
for another German naturalist, Dr. Bernhard Altum, to show the 
importance of specialization and to open up a new field of research 
in the scientific examination of the pellets or castings of the 
Strigidce or Owls. These birds are in the habit of swallowing 
their prey whole, or when too large to be treated in this way, in 
large masses from which the fur or feathers and the smaller bones 
have not been removed. These indigestible portions are subse¬ 
quently ejected in the form of pellets or castings, which may be 
found in large numbers in the nests and roosting-places occupied 
* Another work on the same lines as Mr. Norgate’s paper, but on a larger 
scale, is Mr. J. Watson’s “ Ornithology in relation to Agriculture” (1893). 
