1918.] ' The N.Z. Journal of Science and Technology. 
67 
THE FOOD OF BRITISH WILD BIRDS.* 
By Walter E. Collinge. 
[The control of the acclimatized British and other birds in New Zealand 
can hardly be said to be based on accurate knowledge of the habits of 
the birds. Economic ornithology of the kind described in this article is 
certainly one of the forms of research that should receive serious consider¬ 
ation from any body set up to organize scientific and industrial research. 
The article suggests also the advisability of acclimatizing more of the 
purely insectivorous birds. —Ed.] 
Scientific investigations concerning the economic importance of our 
British wild birds are of comparatively recent date, so that at present the 
sum total of our knowledge is only limited. To arrive at the precise 
economic value of each of our commoner species is a task of no mean 
magnitude, and yet it is slowly but surely being forced upon the minds 
of all thinking people who are concerned with the produce of the land 
and of our fisheries that such work is more and more becoming a necessity, 
and one also fraught with great possibilities. So clearly has this been 
recognized by other countries that special State officers devote the whole 
of their time to the elucidation of the various problems in connection with 
economic ornithology. If a particular species confers greater benefits than 
injuries, and we are not affording it all the protection possible, we are 
pursuing a down-grade and very dangerous course, which cannot fail but 
produce direct injury to the State. 
The subject is a complex one, approachable from many sides, and any 
investigations to be of real value must entail a large amount of careful 
and detailed work extending over some considerable period of time. The 
mere cataloguing of the crop or stomach contents of a limited number of 
specimens of any species obtained at a particular period from one locality 
is really of very little value. As the writer has elsewhere stated,f “ In 
order to arrive at a proper understanding of the food of any particular 
species it is necessary to examine the food contents found in the intestinal 
tract during the different seasons of the year and from various districts. 
Further, careful observations must be made in the field, and of the nature 
of the food brought to the nest by the parents during the breeding season, 
and also of the faecal contents extruded from the nest.’ 5 
We know now that many of the earlier records are either only partially 
correct or will scarcely bear the interpretation put upon them by their 
respective authors, for two most important factors have been overlooked 
—viz., the rate of digestion, and the intestinal food contents found beyond 
the region of the gizzard. The rate of digestion, according to experiments 
at present in hand, would seem to vary in different groups of birds. As 
yet but little work has been done in this interesting field, a more accurate 
knowledge of which must largely alter our ideas of the various statistical 
tables which have been given for different species. 
Under certain conditions— e.g ., during dry summersJ—a much larger 
percentage of weed-seeds pass through the intestinal canal uninjured, due 
to the fact that under such climatic conditions a much smaller percentage 
*Part of an article published in Nature, 7th January, 1915, pp. 509-12, and reprinted 
by permission of the author and publishers. 
f The Food of Some British Wild Birds, 1913, p. 7. 
%Journ. Econ. Biology, vol. 60, 1914, p. 69. 
