Deer & Tick: Town asked to double its 15-unit 4-poster program

The Town Board should budget for a $150,000-a-year 4-poster program that would put 30 units in the field covering half the Island in alternating years, the town Deer and Tick Committee has recommended.

The town budgeted $68,000 this year to put 15 4-posters in the field under a special state permit, down from the $77,000 budgeted during the last year of a three-year study that put 60 units in the field and was funded with help from county and private sources.

The committee’s chair, Patricia Shillingburg, appeared before the Town Board last month to make the case that the 4-poster study effectively eradicated ticks from Shelter Island and should be continued at a level that would continue to suppress the tick population as a matter of public health.

“The county, the town and hundreds of individual contributors — in three years — have spent over $2 million to eradicate the ticks on Shelter Island,” she told the board on September 13. Joining her was entomologist Daniel Gilrein of Suffolk County’s Cornell Cooperative Extension, who presented a summary of the Cooperative Extension’s highly detailed final report on the three-year 4-poster study, which the extension ran under a special permit issued by the state Department of Environmental Conservation only after years of debate and controversy.

The 4-poster device is not approved for use in New York State and the key purpose of the study was to allow the DEC to decide whether or not to change its rules.

Paul Curtis, a wildlife specialist at Cornell University, assisted in the experiment and took part in the September 13 Town Board presentation by speaker phone.

The 4-poster units are so-named because each of two feed bins filled with corn is framed by four posts holding rollers soaked with a solution of the chemical permethrin. The chemical is transferred to the deer’s neck and ears when they lean into the bins to eat. Permethrin is the same chemical used in public health mosquito abatement programs, indoor and outdoor residential sites and on pets and clothing, according to NPIC, the National Pesticide Information Center.

Mr. Gilrein noted that permethrin was found in coat swabs of deer in 36 out of 39 cases, demonstrating that the 4-poster program did work in coating deer with a tick-killing agent. Deer are the prime host of ticks, which congregate on their heads, neck and ears. Mr. Gilrein said decreases in tick population “were relatively greater in areas where 4-posters were used, and 4-posters appear to have had a significant impact” on the Island’s overall tick population.

Mr. Gilrein presented data showing that 4-posters increased indirect contacts among deer “but not direct contacts,” which he said countered a theory that the 4-poster system could cause the spread of disease — one of the reasons the state forbids feeding or “baiting” deer.

The chemical did not impact deer population growth or reproductive success and the 4-poster program did not increase deer-vehicle collisions, according to the final report, Mr. Gilrein said.

The next step for the Town Board is to decide how many 4-poster units to maintain in the field. In the 2008-2010 study, 60 4-poster units were installed to cover the “Area B/North” and “Area A/South” sections of the Island.

At last month’s meeting, Ms. Shillingburg handed out a sheet titled “Deer and Tick Committee Report,” in which the committee proposes the installation of 30 units, costing $5,000 each to maintain and operate, for a total cost of $150,000 a year. In the report, the committee recommends covering the “North” section in 2012 and the “South” section in 2013.

“You may contemplate covering only one quarter of the Island as you did last year,” Ms. Shillingburg said, referring to the 15 units. “This decision, however, is not based on science and, the committee believes, will be self-defeating in the end” because it would allow the tick population to recover.

Ms. Shillingburg warned the board of the dangers of complacency: “The last option is, of course, to do nothing and move on, recognizing that within five years, the Island will have returned to the state where our citizens and our economy are in jeopardy from tick-borne diseases,” she said. “The committee is well aware that it is presenting you with a moral dilemma. There is little money in the till but the physical health of the community and its economic viability are at stake so there is really only one right thing to do.”

“I’d like to see it done,” a man in the audience said at last month’s meeting. “My wife was diagnosed with Lyme again this year … I can’t believe the casual attitude on the part of some” toward tick-borne illness, he said.

Although the presentation was on the topic of tick eradication, questions about the numbers of deer on the Island and the impact of 4-poster placement on hunting were raised by Councilman Glenn Waddington, who is running for town supervisor. He surmised that the deer population is increasing on Shelter Island.

“I don’t exactly want the deer to do fine,” he said.

Mr. Curtis warned that the deer population had to be reduced to 15 per square mile to have a 4-poster program work properly and warned of using a “hodgepodge” approach to their deployment. Installing “15 or 20 and moving them around,” he said, “may not accomplish the goal. I would go for more complete coverage.”

Mr. Waddington said there was an outcry from hunters when the “North” 4-poster study area was closed and again when the “South” was off limits. He said the town should be “ramping up our culling of the deer” but “we couldn’t do that during the study. We didn’t want to skew the results.”

Police Chief James Read objected to Mr. Waddington’s assertion that the town’s special-permit deer-hunt program was falling short because the number of deer taken had been declining. He said there was a natural leveling off of the deer harvest over the years because the hunt had been successful in reducing the herd so it had become harder to bag a deer.

Mr. Gilrein addressed concerns about deer meat being safe to eat after deer had been exposed to 4-posters. Of 20 Shelter Island deer tested, none had the chemical in their  livers and none out of 23 had it in their hindquarter muscles. Six out of 39 deer tested positive for the chemical in their neck muscles. Permethrin was also found on the coats of deer in North Haven, the control area, where 4-posters were not installed. Ten of 15 deer sampled had positive detections of the chemical in coat swabs. Many residents on North Haven have their yards sprayed with a permethrin solution to control ticks, as do an estimated 400 homeowners on Shelter Island.

Vegetation destruction around 4-posters was also measured. Mr. Gilrein said there was some impact on some areas at some distances but that “damage is so high already, it’s very hard to tease out. There is a great deal of deer damage. That was obvious before the study began.”

Town Supervisor Jim Dougherty asked Mr. Gilrein if New York State’s Department of Environmental Conservation was going to allow the use of permethrin in 4-posters in the future. “The DEC has not made a registration opinion yet,” Mr. Gilrein said.

The town’s continuing 15-unit program is allowed under a special permit issued by the DEC to the town.