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Show New Method Helps Find Ages of Deer in Utah It gives more data, better data, and will be of better use to us. That, in a nutshell, Is Rodney John's description of the new deer aging method being utilized by Division of Wildlife Resources biologists. John is big game supervisor for the Division. The new method Involves aging deer by analyzing their teeth. The roots lay down a new cementum layer each year much like trees grow annual rings. These layers are called cementum annuli. One incisor must be extracted from each deer. It is sectioned, stained, placed on slides and the annuli are counted under a microscope. The old method involved aging by noting tooth eruption and wear. "Under the old method, we couldn't break down deer ages by year. Rather, we aged them by groups; i.e., yearlings, 2'i, 3's-7'.j, and old," said John "Additionally, when several people were doing the aging, there was room for error." "Under the cementum annuli method, both of these drawbacks will be eliminated," he said. "We can age deer by the year, and the aging is done by one individual who is highly trained and specializes in this field." More important, though, is what can be done with the date accumulated by this method. "Over a period of a few years, by knowing the actual age of the animals, we can determine the mortalility and survival rates. We can also determine replacement in the herd each year. From this information, we can learn more quickly whether Utah's deer populations are increasing or decreasing," explained John He stressed that this factor is the most important reason for initiating the new technique. The cementum annuli method was first used in 1973 to test its accuracy. That year, five representative deer units throughout the state were chosen where field personnel aged 50 does in the field by tooth eruption and wear; three of the Division's most experienced biologists later aged jaws from the same does in the laboratory; and an incisor from each jaw was taken for the cementum annuli aging method. "The laboratory aging method was assumed to be accurate," said John, "and the cementum annuli method compared very closely." In 1974 some 4,000 teeth were collected. "Again, we used both field aging and cementum anuli methods, and they correlated closely. We will probably do away with the tooth eruption technique next year." John added that the cementum annuli method takes more time and definitely costs more, due to laboratory equipment and the full-time person on the Job, but noted it is justified in that it will, hopefully, determine population dynamics of Utah's deer in a short time in as little as two years, in fact. Dr. Mike Wolfe, of Utah State University, analyzed the samples from last fall and told Division biologists a sample of 150 deer per unit will be adequate, added John, "But the number of deer harvested for the herd unit will determine to some extent the sample size needed." Most deer harvested are under 6 years old, but two were aged at 12 'i years- the oldest on the Division's records. |
