Fig. 8.— Wing of yearling male Canada goose, A, and of an adult male, B. The enlarged, knoblike portion of the car- 
pometacarpus of the adult is conspicuous. 
THE CLOACA 
Within the past quarter century, characters of the 
cloaca have become widely recognized as criteria of 
sex and age in waterfowl (Gower 1939; Hochbaum 
1942; Elder 1946; Hanson 1949). A Canada goose 
can be most easily subdued for examination of the 
age and sex characters of the cloaca if the goose is 
held upside down on the operator’s lap and the breast 
of the bird is firmly tucked under the operator's chest. 
The goose can be readily placed in this position if the 
operator grasps the bird across the humeri with one 
hand so that the front of the bird is toward the op- 
erator. The bird is in position to be placed on the 
operator's lap with a half-turn of his hand. If the bird 
is first held so that it faces away from the operator, 
it must be turned end over end to be in position for 
examination. It is awkward to handle a goose in this 
manner, and the abrupt change in position causes the 
bird to increase its struggles. The struggles of a bird 
being held can be greatly minimized if its head and 
neck are tucked under one wing. 
Internal examination of the cloaca with the aid of 
a nasal speculum, Fig. 9, is relatively simple provided 
the goose is securely held. A metal rod about 2 mm 
in diameter and with a smoothly rounded tip should 
8 
be used as a probe. Extending the cloaca greatly fa- _ 
cilitates probing for the bursa. The oviduct attaches _ 
to the left wall of the cloaca about 15 mm below the 
sphincter muscle. To explore the cloaca for an open- 
ing to the oviduct, the operator should hold the specu- 
lum at right angles to the axis of the bird’s body. The 
site of attachment of the oviduct is most easily in- 
spected if the probe is held nearly parallel to the left 
wall of the cloaca and moderate lateral pressure is 
used to stretch and smooth out the tissue in that area. 
A speculum can be used with no harm to the bird if 
the cloaca is spread open rapidly and firmly. Repeated, 
gingerly made attempts, in addition to causing the 
bird to struggle, are apt to rupture small blood vessels. 
The Sphincter Muscle—The size, conformation, 
and color of the external bare area of the sphincter 
muscle, Fig. 10, provide some immediate clues to the 
age and sex of the bird being handled. In immatures 
of both sexes, the sphincter muscle is flat, small in 
diameter, and pink-red in color. In yearlings, in winter, 
the bare area is somewhat larger and may be slightly 
darker in color. In older, sexually mature geese, the 
sphincter muscle is usually a darker red or varying 
hues of purple. Adult males can usually be distin- 
guished from adult females by the marked convexity 
of the muscle in the males. In adult females, the bare 
