The Montgomery County Department of Parks report on the Whitetail Deer Management Plan for the Norristown Farm Park, dated 2004, was very comprehensive in addressing as many options as possible for dealing with the perceived overpopulation of deer at the Park.  To briefly summarize the conditions at the NFP, which have impact on deer management strategies:

1.      NFP is located in a suburban setting.

2.      Nearby areas of open habitat continue to disappear.

3.      Continued presence of crop farming is part of the master plan.

4.      Wildlife and nature study is another component that brings visitors to the park.

5.      Female deer rarely migrate more than one mile from their birthplace.

6.      Reducing Deer/Car collisions is highly desirable.

The Board of the FPPA is convinced that in this insular habitat, controlling the deer herd size is essential for maintaining ecological balance and meeting the long-term goals of the NFP.

The options discussed in the Deer Management Plan for NFP included:

1. Maintaining the Status Quo
2. Using Repellents/Scare Devices
3. Erecting Fencing and other Physical Exclusion methods
4. Manipulating the Habitat
5. Providing Supplemental Feeding
6. Direct Reduction by the use of Sharpshooters, Depredation Permits, Public Hunting, or Managed Hunting
7. Reproductive Control by use of Surgical Sterilization, Oral Hormones, Implantation of Encapsulated Hormones, and Immunocontraception
8. Trapping and Removing or Relocating
9. Restoring Predators

The advantages and disadvantages were discussed for each option. The control method recommended in the report was Direct Reduction by Managed Public Hunting either by archery or firearms. But the report’s summary stated: “The staff will pursue the implementation of other, non-lethal management methods of the white-tailed deer when suitable options become available and viable.”  Several FPPA Board members reviewed this document and noticed a few things that were not included and some areas where knowledge of the most current information could alter the management recommendations. 

On April 22, 2005, the FPPA Board presented two suggestions to the NFP Advisory Board and offered to assist with these initiatives to help manage the impact of the current rapid expansion of the deer herd at NFP if the Advisory Board chooses to pursue these recommendations.  The Executive Summary stated that:

Ø      The FPPA is proposing two initiatives to help manage the deer herd at NFP and its impact

o       Use of the Strieter-lite reflector system to reduce the rate of deer-car collisions on perimeter roads

o       The use of immunocontraception to directly manage herd size

Ø      Both of these techniques have proven successful in many area of the US but are underutilized in Pennsylvania

Ø      NFP is well positioned to take a leadership role in using effective, modern techniques for managing deer populations in suburban settings in Pennsylvania.

 Deterrent Method for Deer/Car collisions and road kills and injuries:

Use of Strieter-lite reflectors

The deer management report tallies the number of deer/car accidents, road kills, and injured deer that occur on roads around the park. However, the report does not discuss deterrent methods.  Strieter-lite reflectors have been used successfully in the U.S. and Canada in reducing car collisions with deer and moose.  Scientific studies have demonstrated that the Strieter-lite reflectors are 78-90% effective. In discussing the nature of the streets mentioned in the deer management report with Mr. John Strieter, he said that the reflectors would work well on the non-car lined streets (Germantown Pike and Whitehall Road) because the reflectors need to be on both sides in order to produce the moving light grid that deter deer from crossing.  The major reason for failure is lack of simple maintenance, such as washing dirt and deicing material off the reflectors, keeping vegetation down around them, and replacing any reflectors that are knocked down.

If the Advisory Committee is in favor of following up on this suggestion, the FPPA is offering to investigate funding and accept the responsibility of regular cleaning maintenance of the reflectors as another FPPA volunteer run project.

For further information, please visit Mr. John Strieter’s web page: www.strieter-lite.com.

Effective Long Term Deer Management Strategy;

Utilization of Immunocontraception

The most appropriate and effective method for long-term management under the conditions of the NFP is immunocontraception. Unfortunately, in the deer management report, pages 39-42, the reference material cited is quite out-of-date. A film on immunocontraception, produced 12 years ago, conveys wishes by the scientists to have a one-dose immunocontraceptive that lasts multiple years.  These wishes became a reality more than five years ago.  The latest study at the National Institute of Standards and Technology (NIST) entitled, Effects of immunocontraception on a suburban population of white-tailed deer Odocoileus virginianus, by Rutberg, Naugle, Thiele, and Liu, published in Biological Conservation, 2004, demonstrates the ability of this method to reduce population size by blocking conception and reducing the rate of birth. It is interesting to note that the site similar in size and habitat to the Norristown Farm Park.

In fact, a study that has not been published yet shows that the one dose immunocontraceptive still has a 70-80% efficacy of preventing pregnancy after 5 years!

The recommended immunocontraceptive, PZP, works by inoculating females with a pig protein that, like any vaccine, produces antibodies.  In this case, those antibodies block sperm from fertilizing the egg.  Natural behavior and secondary sexual characteristics such as antlers are maintained because there is no hormonal interference.  PZP cannot harm humans or the environment since it is quite simply a pig protein that is broken down in the animal’s own system.  PZP immunocontraceptive has been used for over 30 years in over 100 species of animals.  Since 1990, successful results on free-roaming white-tailed deer are as close to Pennsylvania as NY, CT, OH, NJ, MD, VA, and SC.  So why not in Pennsylvania?

Immunocontraception is more effective long-term population control than hunting because it acts directly on the birth rate of the population.  If hunting is the only management tool for population control, it will require a hunt every year or every other year because of the “population rebound.”  Understanding population rebound is critical to development of a long-range management plan.  Briefly, nutrition controls reproduction and survival rates in many animals, including deer.  Since hunting generally occurs after the mating season, removal of the target figure of 100 deer proposed by the NFP management plan, i.e. approximately 30% reduction, (in an average hunt 20-30% reduction occurs), there is more food available.  Since deer conceive multiple embryos (unlike humans), the does produce more twins and triplets instead of single fawns.  There is also lower neonatal mortality, increased conception rates, and higher prevalence of pregnancy in yearlings.  In the study by Richter and Labisky, the incidence of twinning on a hunted site was 38% compared to 14% on a non-hunted site.  The Fish and Game Agency in NJ reported that surviving females after a hunt had produced enough offspring not only to replace those killed but enough to increase the size of the herd by the very next year.  One dose PZP immunocontraception, on the other hand, has a 70-80% efficacy of preventing pregnancy even after 5 years.

Hunting in urban and suburban settings incurs additional costs in increased security, park image, and potential lawsuits.  Fairmount Park is an excellent example of the problems faced by using only hunting.  After seven years, the deer herds are not decreasing, costs have escalated due to extreme security measures they have had to employ, and there continues to be more lawsuits to battle.  Two excellent examples of long-term success of population reduction by the use of immunocontraception only are: 

Fire Island, NY with a treated population of 215 deer showed a 60% reduction over six years. 

At the 233 hectare campus of the National Institute of Standards and Technology in Gaithersburg, Maryland (which is roughly the size and has similar habitat of NFP) showed 33% reduction over 4 years.

Of course, there are costs associated with immunocontraception as well but the great news is that FPPA has also found five organizations that have expressed interest in funding PZP immunocontraception for deer at the NFP.  FPPA is requesting that NFP Advisory Board consider immunocontraception as part of the long-range management plan for deer.  NFP is well positioned to take a leadership role in using effective, modern techniques for managing deer populations in suburban settings in Pennsylvania.

For more research information on PZP, please visit www.pzpinfo.org.

Come to the Annual Members Meeting on Wednesday, June 7 from 7-9 PM at the Penn Christian Academy on Germantown Pike to learn more about Strieter-lite Reflectors and PZP Immunocontraception and to receive an update on the FPPA proposals to the NFP Advisory Board.

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