New study offers insight on 4-posters
Deer feeding at a Shelter Island 4-poster unit.
The Deer & Tick Committee could be discussing a study of 4-posters — feeding stands that brush deer with a tickicide, permethrin — that advises against employing them.
A 53-page report issued in February by the Fairfax County [Virginia] Police Department’s Animal Service Division and the Fairfax County Health Department, recommended not to continue a three-year deployment of 20 units that has provided one unit for every 50 to 70 acres.
The study compared two sites that where 4-posters were placed versus two control sites that would not use the units. It looked at factors, including:
• Examining deer hosts that were tagged to collect ticks from the animals’ ears
• Tick drags — dragging a flannel cloth through a field — to determine ticks in sites with units and those without them
• Camera monitoring to determine what animals besides deer were feeding at 4-poster stands
• Information of deer health, concerned with whether they might be spreading diseases by sharing food from the units
• Environmental impacts, such as damage to ground cover and soil resulting from deer population in both sites with units and control sites
“It would be counter-productive to current deer control efforts to introduce practices that may encourage population growth in local deer herds through provision of an ample, year-round food source,” the report concluded.
While the units are generally deployed on Shelter Island from March to the end of October, in Fairfax, they were deployed year-round.
The one variable that could differ between Fairfax and Shelter Island is the number of units used to cover the acreage.
When Shelter Island participated in the 2008-10 Cornell University-Cornell Cooperative Extension program, there were 60 units deployed here with an average of 30 to 50 acres per unit, according to the Department of Environmental Conservation.
The results showed a dramatic drop in the tick population, according to the Cornell Cooperative Extension-Cornell University report that included Shelter Island.
But when the Town of Shelter Island took over the program in 2012, it could only afford to deploy 15 units, and in 2013, 19 units.
The tick population was found to increase during that period.
The tick drags showed decreased numbers of ticks since the town has deployed more than 30 units in 2014 and 2015.
Other factors remained identical in both communities as dictated by the Environmental Protection Agency. These factors included the maintenance of units in terms of corn refills and applications of a 10 percent solution of permethrin on rollers meant to put the tickicide onto the animals’ necks.
What could be useful to the Island from the Farifax report are tests of deer identified to have used the 4-posters. Examinations of the deer after harvesting, the Fairfax report says, shows verminous pneumonia, inflamation of the digestive tract and “multiple organ inflammation.”
The examinations showed — but less frequently — other types of pneumonia and infectious diseases. A few showed a “heavy tapeworm load.”
There was no sign of chronic infectious disease of the nervous system — called “waste disease” — in deer that results in distinctive brain lesions. But the study warned that animals that contract it can decimate an entire deer population and those infected could, through their saliva, fecal matter and urine, leave remains that stay in certain soils for a “prolonged” period of time.
The Fairfax study drew no conclusions about whether the animal diseases found in the carcasses tested are transmittable to humans through the meat. It does express “serious concern” for spreading disease among animals feeding at the stations.
Those here concerned about continued use of permethrin have raised questions about the safety of deer meat taken from animals exposed to the tickicide over a period of time, but the Cornell study didn’t follow up on that factor.
Committee members have wanted a follow-up study, but don’t have the money to conduct it here and haven’t been able to secure funds from other governmental sources.
