Assessing the rate of success for localized management of white-tailed deer using roadside observations

Stephanie Hauver

Introduction
Driving down the highway this summer I noticed many dead deer lying on the shoulder of the road. I also heard neighbors and friends complain that their gardens had been destroyed by an over abundance of grazing deer. The question I found myself asking was; what is the best way to manage deer in developed environments? Hunting is not feasible since too many lives may be put at risk and immuno-controception is often too expensive. At Huntington Wildlife Forest I found that the answer to this difficult question might be localized management.

Background
In the middle of the Adirondack park lays a pristine 15,500-acre2 wilderness area called Huntington Wildlife Forest (HWF). This property has been used for teaching and research purposes since 1932. Because of this fact, the scientists here have a wealth of knowledge regarding deer behavior, especially concerning deer habitat and estimated densities over the years. Biologist at HWF found that deer are philopatric, which means that does live in home ranges that overlap with their mothers' as well as sisters and aunts, and that they are very faithful to those ranges. The project that I am currently working on is part of a 10 year study that aims to see if does will stay in their respective home ranges even if an area of low deer density is created next to their range.

Methods
In 1985, biologists began trapping deer using modified Stephenson box traps to equip deer with radio collars as well as numbered cattle tags, so they could be easily identified. Through trapping and radiotelemetry 8 distinct family or social units were delineated. In 1994 one of these social groups was removed from the property to see how the surrounding deer would react to a lush and virtually deer free 1.4km2 area (termed the void).
One way to determine the way the deer would react is to use the roadside observation sheets that every driver on
Huntington property is required to fill out. Theses observation sheet list how many roads the driver drove on, and what wildlife they encountered along the way. If a deer was seen the driver had to record the time of the sighting, where it occurred on the property, the sex, age (adult or juvenile), and presence of tags or collar. The color of tags was noted as does receive yellow tags and buck are given orange ones. From these sheets I was able to calculate the total number of miles driven throughout the southern half of the property. From this calculation I was then able to determine how many miles were driven in and outside of the void. Once I knew how many miles were driven, I then compared that value to the number of deer seen both in and outside of the void to find an observation rate of the deer.

Results
My project involved calculating an observation rate for each summer month (May, June, July, and August) of every year between 1990 and 2000. I then had to determine the observation rate in the void and the non-void areas on the southern half of the property using visual observations of deer for each month of every year. I had to also calculate the total mileage driven as well as the amount of miles driven in and outside of the void. Once these numbers were determined, I divided the two to get the unit of deer per 100 miles. By comparing the different estimated densities before and after the creation of the void, I was able to determine that in 1994 the density did in fact drop down substantially inside of the void. I also found that since 1994 the estimated density within the void has not significantly increased.
The area outside of the void also saw a decrease in the number of deer seen on the property, but this is most likely caused by the harsh winters that the deer are subjected to. Deer only "migrate" to their winter range when snow levels reach 38cm or more, these days represent some of the coldest and most limited in the sense of food. Between 1990 and 1993 the average time that deer were forced to live on their winter range was 45 days, after 1994 the average time spent on winter range was 71 days. It is most likely that the long winters in the past six years resulted in a higher mortality rate amongst deer both in and outside of the void. In my calculations, however, it is still shown that the deer observation rate inside of the void decreased after 1994 from 4 times as high to lower than the observation rate of deer seen outside the void.

Management Implications
This is an important study because it aims to show that even though 14 deer were removed from the void, no deer immediately repopulated the area. If this hypothesis is true, then wildlife officials can better manage heavily populated deer areas by simply removing a social group. Also, private landowners may find localized management a helpful tool in reducing numbers of deer on their property. If they continually hunt their land they can essentially create a deer free area because no does from neighboring areas will leave their home ranges to move onto the property of low deer density. By ridding an area of just one social group, the area may be able to maintain a low density of deer for more than six years, and possibly longer. Although localized management may seem like a lot of work, it is sometimes the only option in residential areas and parks, where hunting is not a possible solution.

About The Author: Stephanie Hauver
I am currently a junior at the College of Environmental Science and Forestry. I will be receiving my degree in Environmental and Forest Biology with a concentration in Zoology. I hope to continue researching animal behavior when I go to Tanzania, Africa my senior year of college. I am interested in the different levels of animal intelligence and hope to get my M.S. studying the social behavior of African Elephants.