Relationship of Sex and Age to Strontium-90 Accumulation in White-Tailed Deer Mandibles

Abstract

Mandibles (plus teeth) of 68 white-tailed deer (Odocoileus virginianus) of various age-classes were collected in December, 1959, at Aberdeen Proving Ground, Maryland, to study strontium-90 distribution within a deer herd. No statistically significant difference was observed in the mean strontium90 accumulated by males and females, but there was a significant difference between age-classes. Further, there was no significant age-class-sex interaction, implying that the difference between age-classes was independent of sex. The amount of strontium-90 in the mandible was correlated with year of birth and the annual strontium-90 increment and total strontium-90 in the soil. There were no statistically significant differences between the variances of the age-classes of either sex. Considerable variation in the strontium-90 content of mandibles within age-classes was observed. Since the advent of the atomic age there has been concern about the accumulation of radionuclides by wildlife populations and the effect of such accumulation on wildlife and on persons consuming harvested game animals. Atmospheric nuclear testing and underground testing, where venting occurs, results in introduction of radionuclides into the biosphere. As a result of short physical half-lifes, many of these nuclides are transitory. Historically, major interest has been directed toward carbon-14, cesium-137, iodine-131, and strontium-90. With the exception of iodine-131, these radionuclides have relatively long physical half-lifes. Strontium-90 has a physical half-life of 27 years and a biological half-life in mammals of about 7.5 years (Hawthorn 1959: 1294). It emits only beta particles, has chemical properties similar to calcium, and is deposited in bone where it has a long residence time. This paper is a report on strontium-90 concentrations observed in deer mandibles (plus teeth) collected from a herd of whitetailed deer at Aberdeen Proving Ground, Maryland, December, 1959. The paper deals specifically with the concentration of strontium-90 in mandibles by sexes and ageclasses of this herd and with the variability in strontium-90 deposition observed. T Aberdeen Proving Ground herd is unique in Maryland. According to Flyger (1958), the herd is apparently at the limit the habitat can sustain. He has observed that it is not unusual to count 100-200 deer in one morning and that a distinct browse line is evident on the area. Instances of mass mortality have occurred in this herd and the average weight of the deer is 20 pounds less than for deer of the same age-class from western Maryland (Flyger 1958). The only published commentary on the past history of deer in this study area is that of Bullene (1949). He states that when the U. S. Government acquired the area in 1917 there were a few deer. We have received unconfirmed reports that deer were not present on the area at that time, that deer were released in 1932 and 1933, that the stock apparently came from Pennsylvania-probably Indian Town Gap Military Reservation -and consisted of one buck and three does. Regardless of the source of deer, it is quite evident that the initial population was very low and that, as a result of fencing, a mimimum influx into the area occurred, thus resulting in a highly inbred herd. The literature on strontium-90 accumulation in deer bone is rather limited. French (1960) analyzed a deer bone collected in the tropics of Ecuador in 1958 which contained