Mayor de Blasio Announces Staten Island Deer Population has Dropped 8 Percent, Pointing to Early Success for Sterilization Study

April 12, 2018

Two years into city’s deer impact management plan, birth rates also fall by half and reductions expected to continue

NEW YORK—Two years into the City’s deer impact management plan on Staten Island, a survey conducted by White Buffalo, Inc and verified by NYC Parks estimates the borough’s deer population has dropped by 8 percent, from 2,053 in 2017 to 1,884 in 2018. In addition, the survey results showed a greater-than 50 percent reduction in fawn births compared to the previous year: the ratio of adult female deer to fawn has fallen from 1:1 to 1:.47. Based on the adult deer mortality estimates and decline in fawn births, the City expects further reductions next year. Year Two of the City’s deer project concluded on March 17, 2018, with a total of 1,154 vasectomies completed, which represents approximately 94% of the male deer population.

“There are fewer deer on Staten Island than last year,” said Mayor de Blasio. “We are already seeing tangible progress from this novel strategy, and earlier than expected. These numbers show that our smart, humane plan is the right one, both for Staten Islanders and their antlered neighbors.”

“Because deer have no natural predators on Staten Island and abundant sources of food in the borough, we can reasonably attribute the significant drop in their population to our human population controls. In short, two years into our study, we can already demonstrate signs of success,” said Parks Commissioner Mitchell J. Silver, FAICP.

At high population levels, white-tailed deer can pose significant challenges to human health and safety through deer-vehicle collisions and associations with tick-borne illnesses, and have a detrimental impact on both forest biodiversity and tree regeneration. Deer have no natural predators on Staten Island and they are assumed to have migrated in recent years from New Jersey.

To determine herd size, White Buffalo Inc collected data from 30 infrared cameras placed in deer-treatment areas. White Buffalo then ran the data through three peer-reviewed methods of analysis – the Jacobson Buck to Doe Ratio (BDR) method, the Lincoln-Petersen estimator for population size, and the population reconstruction method. The mean of the three methods was used to determine the deer population on Staten Island.

The City’s five-pronged deer impact management plan was launched in May 2016, and includes the following elements:

• Sterilization Study: A three-year surgical sterilization study focused on male deer. Sterilization projects focusing on females have demonstrated a 10 to 30% decline in annual population, and male sterilizations are easier to perform and less invasive, promising greater efficacy than female sterilization efforts. A total of 1,011 bucks were tagged and sterilized prior to the Project Year 2 population estimate. Year two of the study concluded on March 17, 2018, with 1,154 vasectomies completed.
• Traffic Safety Measures to reduce deer-vehicle collisions including signage, education, and deer resistant plantings on roadways.
• Extensive public education focusing on living safely with deer in an urban environment, including driver education to reduce deer-vehicle collisions, public health education to reduce the incidence of tick bites and tick-borne illnesses, and environmental education to discourage feeding and encourage the planting of deer resistant plants.
• Natural Resource Protections include new fences around planted forest, tree guards on new trees, deer-resistant plantings and further protective measures.
• Monitoring the health of forests and greenspaces, the number and location of deer vehicle collisions and deer carcasses, and the presence of ticks and the incidence of tick-borne disease.

All wildlife in New York State fall under the regulatory jurisdiction of the State. Following fast-track contract approval by the Comptroller’s office, the City submitted a permit request to the New York State Department of Environmental Conservation which was approved to will allow for the sterilization study to begin fall 2016.

“I am cautiously optimistic now that the innovative approach designed for Staten Island’s unique circumstances is showing positive results in reducing the deer population in our borough, leading to an improved quality of life for our residents and wildlife alike,” said Assembly Member Matthew Titone.

“Mayor de Blasio’s adoption of sterilization as a tool to manage white-tailed deer places New York City at the forefront of an emerging field that is striving to manage deer population numbers humanely,” said Brian Shapiro, New York State Director for The Humane Society of the United States. “We applaud him and the New York City Parks Department on successfully reducing Staten Island’s deer population through one of these innovative and humane methods.”