Understanding DMPs: Quota Setting and Permit Selection
Deer Management Permits (DMPs), often called "doe tags", are a critical part of New York's deer management program. By adjusting the number of DMPs available in individual Wildlife Management Units, we can influence the number of does that are taken by hunters and thus manipulate the population toward desired levels. Annual removal of appropriate numbers of does is essential for ecologically responsible deer management and is beneficial for sustaining biodiversity and maintaining healthy habitat and healthy deer.
DMP Quota Setting
The math involved in setting DMP numbers is actually quite simple, though the process of determining several of the variables in the equation is complex. Here is the essence of the permit setting process:
Step 1. Projected Buck Take X Removal Rate1 = Total # of Adult Does to be Harvested
Step 2. Total # of Adult Does to be Harvested - # Adult Does Taken by Muzzleloader Hunters and Archers and on DMAP tags = Necessary Adult Doe DMP Take
Step 3. Necessary Adult Doe DMP Take ÷ Proportion of Adult Does in DMP Take2 = Total Desired DMP Take
Step 4. Total Desired DMP Take ÷ Success Rate of DMPs = Total # of DMPs to Issue
1 Desired ratio of adult female to adult male deer in harvest
2 This accounts for fawns in the DMP take.
The first two variables (projected buck take and removal rate) are the key places where analysis of deer population trends and management action come into play. The other variables are essentially derived from previous harvest data (for example: "Success rate of DMPs" may be a 3 year average), but we can alter these variables if we anticipate some change in how deer are harvested (for example: "#Adult does taken by muzzleloader hunters and archers" could be impacted by a regulation change). The real art and craft to deer management in New York comes through interpreting the data to project the buck take and in determining the appropriate removal rate.
The process of projecting the buck take involves studying trends in buck harvest relative to previous levels of doe harvest and age structures of previous buck and doe harvests. We incorporate several population indices (bowhunter sighting log, damage levels, winter severity) and evaluate herd health and productivity through yearling antler beam diameters and ratios of fawns to adult does in the harvest.
Similarly, determining an appropriate removal rate (ratio of adult does to adult bucks in harvest) requires analyzing trends in buck harvest relative to previous levels of adult doe harvest. We examine this relationship to identify a removal rate that produces stability at a given population level, allowing for neither growth nor reduction in population. The stability-level removal rate is different at different population levels and is strongly influenced by herd productivity. In some high quality habitats of New York, the deer populations can sustain high removal rates of one or more adult doe to every adult buck. In the poorer quality habitats or areas subject to harsh winter conditions, removal rates may be as low as 0.2 adult does to every adult buck. Once we identify a stability-level removal rate, we relate the current population level to the desired level. If the population is currently greater than desired levels, we prescribe a greater-than-stability-level removal rate, and if the population is less than desired levels, then we prescribe a less-than-stability-level removal rate. The magnitude of difference between our prescribed removal rate and the stability level removal rate depends on our management objective. Typically we manage for conservative changes from year to year, trying to minimize dramatic fluctuations in population levels.
While our intentions usually are for conservative changes, severe winters can have dramatic and rapid impacts on deer populations. In fact, the history of New York's deer population is punctuated with periodic winter mortality events, most recently evident in 2003 and 2004. Though we account for the impact of previous winters when setting DMP quotas, we unfortunately cannot anticipate the severity of the upcoming winter. Other mortality factors such as predation, poaching, and deer-vehicle collisions do influence deer populations, but their impact tends to be fairly constant from year to year or at least the variation in their impact is minimal compared to the potential impact of winter mortality and hunter harvest mortality.
Quota setting is only the first part of the DMP process. The next step is to get the permits in the hands of our hunters. DMPs are issued by an instant selection process at the point of sale allowing applicants who are selected for DMPs to receive their permits immediately. The system is designed to provide equal opportunity for a hunter regardless of whether they apply on the first or last day of the application period. The chances for DMP selection are determined by the DMP quota and the number of applications expected for each WMU. An applicant's chances of selection are also affected by residency status, qualification as a land owner or veteran with disabilities, and the number of preference points accumulated through previous DMP applications. For example:
|Landowner and Veterans
|# Odds of Selection||100%||100%||10%|
|# # Permits Issued||100||250||150|
|# # DMPs remaining||400||150||0|
Actual DMP issuance is impacted by application rates, and predicting the number of applicants is not easy. Fortunately, we have been issuing DMPs for many years and can examine trends in applicant number to make reasonable estimates. Yet application rates vary, and each year we have several units which do not reach our target issuance during the initial application period. If a unit is substantially under-subscribed at the close of the initial application period (October 1 each year), we run another random selection of hunters that were denied during the initial period or, if necessary, open the unit up for a secondary application period in November.
Hunters play an essential role in maintaining appropriate deer numbers in New York and our DMP system is the cornerstone of that process.
|First year with either-sex deer hunting||1952|
|Party Permit established||1962|
|First year an individual could receive more than one DMP||1991|
|Consignment of DMPs allowed||2003|
|Greatest number of DMPs issued||770,990 DMPs in 2002|
|Average number of DMPs issued (2005-2007)||432,162|
|Average annual DMP success rate (2005-2007)||16.2%|