State of the State’s Deer Herd
in poor acorn crop years, like 2012, deer have to search farther and more frequently for food, often leading them to concentrated food sources such as agriculture, early successional areas, and open areas with high forb abundance. Deer sightings increase and their vulnerability to harvest increases substantially, causing higher deer harvests in forest-dominated areas during acorn “bust” years. However, the opposite occurs in years of good acorn abundance by causing deer to become more evenly distributed with shorter daily movements, thus decreasing sightings and harvest. Areas not dominated by hardwoods, like northern Missouri, experience less acorn production effects, which results in a consistent harvest vulnerability more reflective of actual population trends.
Hemorrhagic disease (HD) can cause local deer populations to decline, but often have minimal long-term, large-scale effects. The causes of HD outbreaks are localized and not completely understood. For example, during 2012, Osage County had the highest reports of deer mortality, but the majority of the reports were limited one area, with the remainder of the county minimally affected.
Hemorrhagic disease outbreaks in Missouri are often sporadic (rarely occurring in consecutive years) and severe, while in southeastern states they are frequent (every 2–3 years) and mild. Missouri experienced significant HD outbreaks previously in 1988, 1998, and 2007; however, the 2012 outbreak appears to be the most widespread and intense on record in Missouri. Unfortunately, there is no way to quickly determine the HD–related mortality within affected areas. Also, the reports that we received are only a small proportion of the mortality that actually occurred as many go unreported.
Ultimately, the population response to an HD outbreak is related to the amount of mortality and growth rate of the population. As mentioned previously, growth of the population is related to births and deaths. If a population has more does than bucks, it will have a higher growth rate than a population of similar total size, but with equal numbers of bucks and does. Additionally, harvest rate greatly influences how a population responds to an HD outbreak. For example, an area where less than 20–25 percent of the adult does are being harvested consistently will recover quicker than a population with doe harvest greater than 20–25 percent. As a result, deer populations vary across the state and will respond in different ways to the recent HD outbreak. Ultimately, the populations with low growth rates coupled with high harvest rates