Surveys
 First, as most of you can imagine, counting white-tailed deer is an inexact science at best. By their nature, whitetails are secretive, hiding in some sort of cover most of their lives. Counting deer requires "seeing" through this cover or waiting until they are out in the open. And even if deer were easy to count, a complete census would be difficult to coordinate and expensive to conduct. Instead of a complete census, the department relies on surveys of the deer population each year. These surveys are designed so that we can compare the results from year-to-year to see what "trends" have developed. Surveys are not used to directly estimate the total number of deer that are alive at any one time. Instead they are used as an index to the population. 

By examining the results of the surveys we can determine if the deer population appears to have increased or decreased through time. We currently use 3 techniques to provide us with deer trend information. One of the original sources of information that is used to keep track of deer populations is the number of deer that are killed on our highways. These numbers have been collected since 1951. A second survey was initiated in 1978. The spring spotlight survey is designed to give us a handle on changes in both raccoon and deer populations. The final technique is aerial counts of selected areas across the state following the hunting seasons. This survey was first flown in 1983. All three surveys provide useful information. However all have their weaknesses too. 

Next I'll describe each survey in more detail and try to explain how they are used to make management decisions about our deer herd. 

Roadkills
The number of deer that are killed on our highways theoretically should provide a good index to deer numbers. As the deer herd increases or decreases the number of deer hit should also increase or decrease. However it is important to adjust the kill for the number of miles driven on the highways. Thus, kill per million vehicle miles provides a suitable index. One big advantage of this survey is the fact that roads are well distributed throughout the state. This wide distribution along with year-round traffic should provide good coverage of the entire state. Another advantage was that the information was readily available since our officers were required to handle all dead deer. This worked well back in the 50's and 60's when a deer accident was rare. 

However as the number of accidents increased the burden placed upon our officers became too large. Beginning in 1985 the chore was officially shared with the DOT. Conservation Officers still handle deer that someone wants to salvage, but when the deer is left along the road the DOT maintenance crew has to deal with it. They keep a separate set of records for these deer. The final tally for the year is made combining both sources of information. Other factors which probably affect the roadkill include extremes in weather such as the flood of 1993, changes in speed limits and changes in the landscape such as we've experienced with the CRP. 

Spotlight Survey
This survey was evaluated during the 1970's for both deer and raccoon. It appeared to produce consistent results for raccoons but was somewhat more variable for deer. In 1978, 87 routes were set up across the state. Each route is 25 miles long and follow gravel roads in some of the better deer habitat. Counts begin 1 hour after sunset in early April, with wildlife and enforcement personnel working together to survey both sides of the road. An advantage of this survey compared to the roadkill numbers is that it is an active survey. An attempt is made to count the number of deer along specific routes under comparable conditions each year. Because of this, trends should become evident over time. This survey tries to count deer when they are more likely to be out in the open. 

As mentioned, the results from this survey seem to be a little more variable than we would like ideally. The factor that seems to affect this survey the most is the stage of green-up when the routes are run. If green-up occurs early, the deer begin to disperse and are more difficult to spot due to the new leaves. If green-up is delayed the deer are more easily sighted. Green-up can occur pretty early in some years. 

Aerial Counts
Aerial surveys for whitetails are used in a number of states in the midwest. This survey is designed to try to "see" through cover by placing the observer above the deer so they can look down and count the number of deer in an area. Complete snow cover is required for this survey, otherwise the deer do not stand out. Ideally a fresh snow helps hide debris and old deer beds which tend to look remarkably like a deer when you are traveling along at 70 mph at 400 feet above the ground. 

About 350 different areas are surveyed annually in the state when ideal conditions exist. Each area is mapped out and flown using small fixed-wing airplanes. Usually there are 2 observers, a navigator and the pilot in each plane. The navigator keeps the pilot on course and records information while the observers count the number of deer seen on their side of the plane. Each observer can survey 1/8 mile wide strip on each transect across the area being surveyed. The plane turns and keeps flying transects until the designated area is covered. In some cases the area being flown is just 1 long transect along a creek or river. Again this is an active survey where results should be comparable from year-to-year. 

The main advantage of this survey is that it provides information at a critical time of the year. Surveys are flown just after the hunting season so they should provide us with a good idea of how things went during the season. Factors that affect this survey are the amount of fresh snow, the amount of disturbance in the area being surveyed and the weather before and during the survey. Under good conditions most deer are probably seen on each transect. However if beds are present, or stumps are visible it can be difficult to see all the deer. If an area happens to have a bunch of snowmobiles using it or has someone cutting trees, the deer may have temporarily moved away from the area being surveyed. 

On the other hand prolonged cold weather may bunch deer up in some of the better wintering areas. And a rough flight due to windy conditions can make counting deer seem less of a priority than keeping one's stomach under control. Probably the worst problem faced is that acceptable snow conditions may only occur 1 or 2 times all winter. Passing up a chance to complete the survey waiting for the "ideal" conditions may very well mean that another chance doesn't come along. A less than ideal survey is better than no survey at all.