Methods of Examination. 



CHAPTER III. 



METHODS OF EXAMINATION. 



" To obtain adequate knowledge of the food of birds in relation 

 to agriculture, a definite scheme of procedure must be followed. 

 Simply observing the birds while they are feeding gives only frag- 

 mentary information . . The results thus obtained must be 

 supplemented by other and corroboratory evidence." 



SYLVESTER D. JUDD. 



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 ne&t. 



If the collection of this information extends over the whole of 

 the twelve months of the year, for successive years, and in different 

 localities, and provided sufficient care is used in the identification 

 of the food materials and their percentages, I believe a very correct 

 idea may be formed of a bird's food and whether or not the 

 particular species is injurious or beneficial. 



Various methods of examination have been recommended, 

 those carried out by myself are as follows : 



1. Examination of Stomach, etc., Contents. 



In nearly all cases the stomach contents have been examined 

 when fresh, viz., four to twenty hours after the birds were shot. 

 Stomach contents preserved in alcohol are preferable to those 

 preserved in formalin, but neither are satisfactory. 



On opening the body-cavity the whole of the intestinal tract, 

 from the oesophagus to the rectum inclusive, was removed and laid 

 in a flat-bottomed, shallow, white dish, here the whole length was 

 slit open with a pair of scissors and the entire contents removed, 

 partly with the aid of a scalpel, forceps, a brush and a little water. 

 The contents were then spread out over the dish and examined 

 with a large magnifying glass. With forceps, all the seeds were 

 transferred to a smaller white, shallow saucer, insect remains to 

 another, vegetable matter to a third and so on. The remaining 

 material was washed several times and the residue subjected to 



