Two laboratory techniques were used for determining the ages of deer from the lower jaws or mandibles--a tooth replacement and wear technique (Severinghaus 1949) and an incisor-sectioning method (Gilbert 1966). The tooth-wear technique requires only the molariform teeth but it is more subjective and inaccurate, particularly in older deer (Ryel _et al._ 1961). Incisor sectioning requires only incisors and appears to be much more accurate.
However, because the incisors had been lost from many of the wolf-kills, and because the tooth-wear technique was used at checking stations, both methods were applied in the laboratory. Mr. David W. Kuehn (1970) sectioned and aged the incisors. Fortunately there was a sufficiently large sample of mandibles with molariform teeth and incisors from both wolf-killed and hunter-killed deer to enable us to devise a table showing the actual ages (based on incisor-sectioning) of each of the jaws assigned to various tooth-wear classes. This table was then used to distribute the ages of specimens that contained only molariform teeth. For example, because it was found that 37 percent of the jaws aged 4-1/2 years old by tooth wear were actually 5-1/2 years old, we assigned 37 percent of the incisorless jaws aged 4-1/2 by tooth wear to the 5-1/2-year category. Similarly, another conversion chart comparing field age determinations of hunter-killed deer with ages based on incisor sectioning of the same jaws was employed to distribute the ages of field-aged, hunter-killed deer for which jaws or incisors could not be collected.
We flew a total of 480 hours during this and related research, mainly during January through March 1967 and December 1968 through March 1969; about one-third of this time was devoted primarily to searching for kills. Jaws were examined from 93 wolf-kills and 49 probable wolf-kills.
[Illustration: _Figure 6.--All hunter-killed deer examined were checked for age. (Photo courtesy of L. D. Frenzel.)_]
Hunter-check stations yielded information from 335 deer (fig. 6), and data on 98 additional hunter-killed deer were contributed by other hunters. Incisors were collected from 82 of 214 hunter-killed deer checked that were older than yearlings; comparisons were then made between ages of the deer based on incisor sectioning and those based on field checks using the wear method. Similarly, incisors were sectioned from 195 wolf-killed and hunter-killed deer older than yearlings that had been aged by the tooth-wear method in the laboratory, so that these two methods could be compared (Kuehn 1970). (Note: incisor-sectioning is unnecessary for fawns and yearlings because animals of these ages can be aged objectively by the progress of tooth replacement.)