Efforts to evaluate deer movements and response to 4-Poster devices are underway on Shelter Island and in North Haven. During January-April, deer are captured in cages or nets that are easily set up on the properties of cooperating community members. Deer are handled humanely, in accordance with protocols filed with the Cornell Institutional Animal Care and Use Committee and following NYS Department of Environmental Conservation Special Licenses Unit procedures. Captured male and female deer are fitted with numbered ear tags allowing unique identification of individuals. There are currently 31 mature female deer on Shelter Island and 17 mature females in North Haven fitted with VHF and GPS collars. These collars provide movement data so that deer home ranges can be mapped in study communities. Fine scale movements of deer in relation to roads and 4-Poster devices will be examined. To determine the impact of 4-Poster device placement on the community, deer-vehicle collisions and vegetation damage, resulting from deer browsing, will be evaluated. Research staff will monitor the deer fitted with collars regularly. A vehicle equipped with antennas, receiver and other field equipment will be seen frequently during the day and night in the community. 

The movements of collared deer are continually monitored (3-4 times a week) on Shelter Island and North Haven using VHF and GPS technology. One may notice the difference in the collars simply by sight; VHF collars are white and GPS collars are black.

VHF (very high frequency; radio frequencies between 30 and 300 MHz) collars are one of the most common technologies used to track wildlife. The VHF collar (transmitter) emits a radio signal that can be picked up by a receiver. Using a directional antenna plugged into the receiver, collared wildlife can be located and movement can be tracked. When the directional antenna is pointed directly toward the transmitter (collar), a strong radio signal is received and as the antenna is moved, the signal weakens. VHF technology requires 4-Poster staff to actively collected movement data on a regular basis in order to monitor deer movement.  

GPS (Global Positioning Systems) collars employ a more advanced technology and are now being widely used to track wildlife. Similar to GPS units used for recreation and marine and land navigation, these collars use satellites to obtain location information for each deer. The GPS receiver (collar) receives a signal from a GPS satellite and uses this to determine its distance from the satellite. When this communication can occur between 4 satellites and the GPS receiver (collar) simultaneously, the GPS receiver uses the distance information to calculate its position at that time with a typical accuracy of 5-15 meters. A computer is used to communicate with each GPS collar on a regular basis and this allows researchers to obtain movement data that are stored in the collar’s memory.

Deer Photo Surveys

In conjunction with tracking deer movements with GPS collars, infrared-triggered cameras will be used to collect information on deer visitation to 4-Poster devices or pre-established bait piles. Photo surveys will occur on Shelter Island and in North Haven, allowing researchers to estimate deer densities, mortality, fawn recruitment, and sex ratios. Photo surveys on Shelter Island will be conducted at 4-Poster device locations to monitor use of devices by non-target wildlife, and deer-to-deer contact.