On New York's Fire Island, scientists fenced deer out of two sites; over 4 years, young lone star ticks were reduced by 48.4%, but adult ticks were not controlled

Summer is a time for sun, sea and sandals. However, if you’re lucky enough not to have anything on your calendar, you may be greeted with a little hitchhiker attached to your ankle that you won’t notice until tomorrow. While many of us have previously thought ticks were only an issue to worry about on our camping trips, if you’re spending any time outside you might be wondering how people manage to keep these pests at a minimum.

According to a 2002 study titled “Effect of deer exclusion by fencing on abundance of Amblyomma americanum (Acari: Ixodidae) on Fire Island, New York, USA,” conducted by Ginsberg, Butler, and Zhioua and published in the Journal of Vector Ecology, researchers tested a simple idea to see how effective it could be. The study was completed on Fire Island, New York, in an area where, by the time researchers set up the experiment in the late 1990s, lone star tick numbers had been rising for years: an early sign of a northward expansion that has only continued since.

A controlled experiment, not a backyard project


Researchers erected game fencing around two roughly one-hectare (2.5-acre) plots within the Lighthouse Tract, then tracked tick populations inside the fencing against unfenced control sites nearby. It was a tightly controlled, multi-year field experiment: keep deer out of defined plots, and measure what happens to the ticks living there.

It was found that the nymphs (the intermediate stage in the lifecycle of ticks) were reduced by an average of 48.4% over 4 years. However, these large exclosures did not help control adult ticks. The nymph numbers also fluctuated greatly throughout each year. This showed that deer numbers weren’t the only factor that caused a large impact on tick numbers.

How much do deer actually matter?

While deer clearly play a role, how much they matter depends heavily on the tick species involved and the method used to study it. It’s worth flagging that the Fire Island study above looked at lone star ticks, while the next study concerns a different species: the blacklegged tick, the one that actually transmits Lyme disease. According to Kilpatrick, Labonte, and Stafford, in their 2014 paper titled “The Relationship Between Deer Density, Tick Abundance, and Human Cases of Lyme Disease in a Residential Community,” published in the Journal of Medical Entomology, a 13-year study of the Mumford Cove community in Groton, Connecticut, found that white-tailed deer are the primary host for adult blacklegged ticks.

Within the community, they had hunts that reduced deer density to 5.1 per square km. This saw a reduction of 76% in tick abundance and 80% fewer Lyme disease cases reported by residents. This study was very different from the previous one. The tick they focused on was different; they used hunting rather than fencing, and they only looked at one residential community. This is likely why the outcomes diverged.

Why lone star ticks are on more people’s radar

Lone star ticks can cause some serious issues. According to CDC researchers writing in MMWR, Alpha-gal Syndrome is an allergic reaction to tick bites that can be fatal. There is currently no treatment or cure available. The syndrome causes people to become allergic to a sugar found in most mammalian meats and products. During 2017-2022, 90,018 people (30.5%) of the 295,400 people who submitted blood samples for alpha-gal testing tested positive.

This number increased from 13,371 in 2017 to 18,885 in 2021. Most cases were reported in areas where lone star ticks are established or reported. Suffolk County, New York (where Fire Island is located), saw the largest number of suspected cases (3,746). However, it is unclear if this is due to increased awareness or an actual increase. Also, not everyone will have been bitten where they live.

The fencing created a reduction in young lone star ticks on Fire Island but had little effect on adult ticks. The fluctuation across each year shows that there are other factors, not just deer, that can affect the numbers. The CDC, for its part, now recommends folding alpha-gal syndrome into community tick-borne disease outreach. Taken together, the two fencing and hunting studies suggest deer removal can meaningfully dent tick populations, but only as one piece of a messier, species-specific puzzle, not a standalone fix.