3. PREPARING SKINS 29 



must be taken with some birds such as the birds of prey in which there may be 

 paired ovaries in the same position as the male testes. The ovary is flattened, 

 elongated, and asymmetrical in shape, and has a granular appearance due to 

 the presence of the oocytes, the rudimentary eggs. In the non-breeding 

 season when the latter are small the ovary may appear as little more than a 

 whitish film (fig. 20d). In the breeding season the granular mass is more 

 obvious (fig. 20c) and may at times be very large and include several incipient 

 egg-yolks. Whereas the testes have thin paired ducts leading to the vent, the 

 ovary has a single, thicker and more obvious oviduct. In immature birds 

 the oviduct is thin and straight but in birds which have bred it is convoluted. 

 Note the sex on labels and any other data records, the males being indicated 

 by c?, females by $. Where there is any doubt indicate this with a question 

 mark. In addition a small diagram indicating the actual size of the sexual 

 organs, with indications of any developing yolks in breeding females and 

 notes on whether the oviduct was convoluted, and whether any forming 

 egg was present in the oviduct, should also be added. 



Crop and gut contents 



It is often difficult to discover the food of a species under natural conditions 

 and a note of the contents of the crop and gut, or the preserved contents of 

 these, may be of considerable value. The collector should remember that it is 

 probably far easier for him to identify food remains, either plant or animal, 

 while on the spot, than it is for someone else to do so not knowing what was 

 present. 



Seed-eating birds usually accumulate a large amount of seed in a crop at 

 the base of, or to the side of, the neck, prior to digestion. Since this seed has 

 not reached the digestive juices it is easy to preserve, if so desired, simply by 

 removing the crop with its contents, cutting through the gut above and below 

 it in the case of a large bird and allowing the whole to dry, placing it in a 

 paper bag or envelope before it disintegrates. The gut contents are obtained 

 by opening up the alimentary canal, identifiable remains being found in the 

 upper parts as far down as the stomach and gizzard, but being unlikely to 

 occur in the intestines. The remains are more difficult to preserve and should 

 be put into corked and labelled tubes containing a solution of about 10 

 percent alcohol. All remains should be carefully labelled with the collector's 

 number for the bird specimen, the name of the species, and its age and sex, 

 the locality and date. 



Where the contents are merely noted some effort should be made to be as 

 specific as possible. Merely to put "seed" or "insects" give relatively little 

 information. If possible the size of food particles and the relative propor- 

 tions of different sizes taken should be indicated. In examining gut contents 

 it should be remembered that in general it is only the relatively hard or 

 indigestible remains that will be identifiable and soft or semi-liquid foods 

 may leave no recognisable remains. 



Internal parasites 



Parasitic worms occur frequently in the intestines of birds and may also 

 occur in other body tissues. For intestinal worms the easiest collecting 

 method may be to preserve a large portion of the gut in its entirety. If 

 parasites are found elsewhere in the body a portion of the tissue containing 



