Deer Problem? Study Used In Count is Flawed (Letter to the Editor)
Writer said method used in deer overpopulation survey is flawed; EAAB didn't follow protocol.
The Avon Lake Environmental Affairs Advisory Board (“EAAB”), consisting largely of private citizens of Avon Lake, was first established in 1994. Since that time, it has advised Avon Lake’s City Council on a wide range of environmental concerns which do or may face the city. One recent issue facing Avon Lake, according to some, is whether there is a deer population problem and, if so, what to do about it. After at least eighteen (18) months of attempting to assess this issue, the EAAB has stated, in writing, that the “estimated population” of deer within the city limits of Avon Lake is “greater than 250.” EAAB has used this alleged “population” number as the basis to (1) conclude that there are “too many deer in Avon Lake” and (2) recommend that bow hunting be permitted within the city limits to reduce this number. What has recently come to light, however, is the flawed methodology used by the EAAB.
The EEAB utilized what they called a “spotlighting survey” to arrive at the above “deer population” estimate within Avon Lake. Instead of hiring professionals to conduct such a survey, the EAAB members attempted to conduct this survey themselves. They drove around the City in teams of two (2), which largely consisted of EAAB members, their spouses and their friends. These groups shined spotlights into undisclosed and unidentified areas while seated in a car. This was done during three timeframes: January of 2011 (12 trips), June of 2011 (6 trips) and November of 2011 (6 trips). The various teams claimed to have spotted anywhere between 0 – 73 deer on these 24 total trips. The EAAB selected the highest single daily count (73) and multiplied it by 3, which equals 219. They then seemingly added an additional 50 or so to that number to arrive at the “deer population” figure of “greater than 250.”
What the EEAB has failed to inform the public is that “spotlighting surveys” are not intended to identify a deer “population” count or to estimate deer population or density. The recognized method of obtaining an accurate deer population count is through an aerial survey. An aerial survey can be done visually or with the assistance of infrared cameras. ODNR utilizes both of these methods for estimating Ohio’s deer herd numbers. ODNR does not, however, utilize “spotlighting” for this purpose. The aerial surveys are done in the late fall/ early winter after the leaves have fallen off the trees and preferably while there is a few inches of snow on the ground (so that footprints can be followed as well). Certain professionals have also conducted infrared ground counts to arrive at deer population estimates. These methods are used to establish a “baseline” or an actual deer population count.
“Spotlighting” is intended to be used after a baseline deer population count has been established through one of the above-recognized methods. The spotlighting counts are performed each year thereafter so that population trends can be identified (i.e. are the numbers growing or declining) relative to an accurately established baseline. If performed yearly in a consistent manner, population deviations from the baseline can be identified through spotlighting. For example, the city of Solon, when it started its deer culling program, had an aerial survey performed so as to get an accurate count of the actual number of deer within its city limits. For the years thereafter, a form of ground counting was performed to see if the baseline number was growing or declining. The Avon Lake EAAB, however, skipped the first step and went right to the spotlighting, which means that we still have no reliable estimate of the deer population within Avon Lake.
Perhaps even more disturbing than EAAB’s public representation that their spotlighting established a “deer population estimate” is the mysterious extrapolation that is used on its data. The formula EAAB applied was “# of deer seen x 3 + 50 = estimate of deer population." The ODNR biologist who was consulted on this issue had never heard of this formula, nor could this writer find anything resembling this formula in the wildlife literature. Studies conducted by professionals warn against using spotlighting data as anything other than a “reference.” White-tailed Deer in Oxford Ohio: Population Assessment and Implications for the Community - University of Miami Institute of Environmental Sciences, Public Service Project 2007-4.
If the formula itself was not bad enough, the EAAB the selected the single highest daily count for the entire year (73) to plug into this formula. Recall that the spotlighting surveys identified deer numbers ranging from 0 - 73, with the average number of deer sighted per spotlighting trip being 31. So the EAAB’s methodology for its “greater than 250 population estimate” was actually “max. # deer spotted during the entire year (73) x 3 + 50 = 269.” Interestingly, Solon, after it conducted its initial aerial survey, used a multiplier of 1.55 to its surveys to monitor population trends. This means that EAAB’s formula would result in more than double the number of deer that Solon would identify based upon the same data! EAAB’s formula appears to be calculated to significantly over-estimate the number of deer in Avon Lake in order to justify its clearly voiced desire to allow bow hunting within city limits.
The EAAB’s spotlighting survey, unfortunately, cannot even be used for its proper purpose, which is comparison with subsequent spotlight surveys to identify trends in population. This is because the surveyors failed to identify exactly where they surveyed and how many hours they spent per survey. This dooms any subsequent survey because there is simply no way to reliably replicate what was done in 2011, either in location or time spent. EAAB, for whatever reason, did document items such as barometric pressure and relative humidity, which, will not assist in consistent survey replication in future years.
Lastly, EEAB did not even follow its own protocol for the “spotlighting survey.” Its protocol required that “the study must be done with no rain, snow or heavy wind since these affect visibility and may drive deer deeper into the woodland areas.” Despite this directive, the EAAB members, with family and friends in tow, proceeded to survey during wind conditions as high as 33 mph and during thunderstorms! It is unknown what, if any, other deviations from protocol occurred.
The entire notion of city-wide “deer population” estimates as a basis for identifying a “problem” also ignores the fact that such estimates, according to experts, serves no purpose in identifying (1) whether there is a “deer problem” or (2) what the potential “solution” should be. While this is not the primary subject of this letter, experts opine that the “solution” to any actual “problem” should be handled in that specific area, not city-wide. For example, the Deer-Vehicle Accidents (“DVA”) in Avon Lake occur primarily in the northeast quadrant of town and in areas where the speed limit is 35 mph. The proposed viable “hunting grounds” are primarily in the southwest quadrant of town. Because deer are highly territorial (home range of between .5 – 2.0 miles), hunting deer in the southwest quadrant of Avon Lake will do little, if anything, to address the alleged “problems” in the northeast quadrant.
This writer readily acknowledges that the EAAB provides a valuable service to the City of Avon Lake and is made up largely of good, hard-working people. This writer also wants to make clear that this is not an indictment on the City of Avon Lake, its officials or its City Council, who are simply relying upon the EAAB, in good faith, for accurate information. It is unfortunate, however, how the “deer population estimates” were performed and how they were portrayed to the residents of Avon Lake. It is equally unfortunate that the City, after eighteen months of study, has not been provided with a reliable indication of how many deer are within its city limits. Any recommending to kill a significant number of deer within Avon Lake should not even be considered unless and until the EAAB (or perhaps someone else) is able to provide accurate answers to certain fundamental questions. So far, that has not happened.
Daniel R. Haude