Efficacy Of Strieter-Lites Not To Be Denied

By Peter Muller

In a previous issue http://abolishsporthunting.org/journals/can-we-reduce-deer-car-collisions/ we reported on the success of Strieter-Lites, a system of reflectors which, if properly set up along a roadway, will reduce deer-car collisions. Numerous studies and installation have reported the effectiveness of the devices. The Georgia Department of Transportation (GDOT) funded a study by the University of Georgia (UGA) to reexamine the efficacy of Strieter-Lites. The study was reported in Volume 34, Number 4, of the Wildlife Society Bulletin in an article entitled “Evaluation of Wildlife Warning Reflectors for Altering White-Tailed Deer Behavior Along Roadways,” by Gino J. D’Angelo et al. Gino J. D’Angelo, a graduate student at the University of Georgia, concludes that reflectors were ineffective in preventing deer-car collisions.

The reflectors that were putatively found to be ineffective were Strieter-Lites, in spite of the fact that other studies had found them to be 50% to 100% effective in preventing deer-car collisions.

(“A Study of the Effectiveness of Strieter-Lite  Wild Animal Highway Warning Reflector Systems” by Robert H. Grenier at http://www.strieter-lite.com/images/scientific_report.pdf ) The discord of the Georgia study with a wide body of evidence to the contrary invites a closer look at the UGA study.

The UGA study protocol consisted of observing deer at night with an infrared camera along a campus road at the UGA and evaluating their behavior as cars approached. In their collection of data, the observer chose one deer from a group near the road (no criteria for the choice of the observed animal are provided) and recorded that deer’s motion as the car approached. The subject’s motion was described as the relative distance moved along two axes, one parallel and one perpendicular to the roadway.

The study fallaciously assumed that only motion away from the roadway along the perpendicular axis would constitute a successful response of the subject to the Strieter-Lites. This assumption is the most obvious and fundamental flaw in the study. The function of Strieter-Lites is to prevent deer from bolting across a roadway when a car with headlights approaches after dark.

Strieter-Lites make no claim to effect the motion of deer along the roadway when they are not about to enter the roadway in the presence of an oncoming car. The data show that the deer grazing along the roadway continued to graze along the roadway and execute what seemed an essentially random movement along the axes being observed. Nothing in those data refuted any claim made for the efficacy of Strieter-Lites. It is even more surprising that such a basic flaw in the study escaped the peer-review of the Wildlife Society Bulletin.

In summary, the data showed a behavior of the subject deer that simply fails to support, much less establish, the conclusion of the study in the most basic way.

Other parts of the study are also weak. The site chosen is on the UGA campus; the deer there are habituated to constant traffic and people. Not surprisingly, they fail to take special note of traffic and people in their vicinity. Most deer-car collisions occur in rural/suburban settings where essentially deer-in-the-wild come only occasionally into contact with motorists. It seems that a study measuring the effect of those reflectors should be set up in such an environment.

Further, the lack of criteria for choosing a subject to follow upon the approach of a vehicle seems very suspicious and invites the “cherry-picking” of data points by the observer. Did the observer consistently pick the deer furthest from the road so that movement even further away from the road was less likely to occur? Did the observer pick the most placid deer so that less movement would result due to the temperamental disposition of the subject animal chosen? Did the observer pick a deer that was moving with a group so that its feeling to maintain cohesion with the herd outweighed any disposition on its part to move independently? The lack of criteria for choosing a subject suggests a basically flawed study.

The major failure of the study remains its failure to observe data that have relevance to the effectiveness of Strieter-Lites. That the deer do not move away from the roadway is no more relevant to the efficacy of Strieter-Lites than that the deer did not start jumping up and down, or that they did not attempt to climb trees. Strieter-Lites make no claim to cause or prevent any of these behaviors that did not occur. They are designed to prevent deer from bolting across a roadway when a car with headlights is approaching – and that they evidently do exceedingly well. In the six-month study only a single car-deer collision occurred; the “normal” number of collisions is between 12 and 24 collisions a year. The proper, unbiased, scientific conclusion is again that Strieter-Lites work exceedingly well.

Peter Muller is VP of C.A.S.H. and has written articles for the C.A.S.H. Courier.


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