December 30, 2006

Deer Research and Data Use

The 2005-06 deer season marked a change in how the Deer Project collects yearly deer age and related biological data. With the introduction of telephone and Internet check-in, check stations were no longer available to gather needed biological data from deer. Instead, DNR Wildlife and Heritage staff, along with volunteers, examined 3,836 deer that were brought to butchers shops across the state during the first part of the 2-week firearms season.

Like the deer brought to check stations in previous years, deer examined at the butcher shops were sexed, aged, and antler measurements were recorded for bucks. Deer were also checked for evidence of illness or disease.

The yearly sample of harvested deer provides valuable that is used to estimate deer population numbers and to detect any changes in deer herd reproductive potential. It is also used to monitor the overall health of deer and the effects of changes to seasons and bag limits made to better manage deer populations.

Staff and volunteers determine the age of each deer by the wear and replacement of its teeth. As young deer get older their milk teeth are replaced with permanent teeth. As adult deer age, their permanent teeth begin to wear down. This enables biologists to reliably categorize deer as fawns (less than 1 year old), yearlings (approximately 1.5 years old) or adults (2 years and older). The proportions of deer in each age class and their gender are then used in reconstruction models to develop and follow trends in the state's deer population.

The antler beam circumference measurements of yearling male deer that are brought to butcher shops are used as indicators of the reproductive potential and health of the deer herd. Yearling males in good habitat with moderate deer numbers will weigh more and have larger antler beam diameters. Abundant food and modest competition translates into more energy available for antler and body growth. This is most evident in the yearling age class. Trends in these measurements can indicate deer herd over-population and habitat degradation. Overall, Maryland's long-term data for these indicators show healthy, productive deer populations across the state.

Deer that are checked on opening day are also examined for evidence of hemorrhagic disease; a viral disease spread by biting midges. Hemorrhagic disease, or "Blue-tongue", commonly appears in late summer and early fall. Deer that have survived hemorrhagic disease and are harvested will exhibit hooves with sloughing or peeling tissue. These deer are still suitable for human consumption. Hemorrhagic disease occurs yearly in Maryland, although it varies in intensity. The results of this statewide examination are reported to the Southeastern Cooperative Wildlife Disease Study in Athens, Georgia as part of a nationwide survey. This study is one of the oldest and most complete nationwide wildlife disease investigations.


Source: Maryland Dept of Natural Resources