GPS Radio Collars Tracking Deer for Next 5 Years

By Lisa Kane

How many of you apply for an Any Deer Permit each year? These much sought-after permit allocations are based, in part, on MDFIW’s estimates of the previous winter’s deer mortality, previous season’s actual hunter harvests and biological information collected during each hunting season on harvested deer. Another part of the equation is called the Winter Severity Index, or WSI. Regional wildlife biologists gather weather data weekly from 28 stations statewide to record temperature (via continuous automated data logging), snow depth and deer sinking depth. The data is applied to estimate how hard the winters are on the overall deer population, and extrapolate winter deer mortality. All of these factors, plugged into a mathematical formula, can directly influence the number of Any Deer permits issued within each Wildlife Management District (WMD).

In use since 1950s, Maine’s deer allocation system has worked very successfully; however, with a changing climate, changing landscapes, and perhaps, missing data for the 2 extremes of our winter weather – the very mild and the very severe – it was time for the WSI system to be re-evaluated. Kyle Ravana, the lead MDIFW deer biologist, recently initiated a 5-yr study to conduct deer population monitoring using GPS satellite collar technology to track survival and mortality trends in Maine’s antlerless deer – i.e. does and fawns.

WMD 17 in central Maine was chosen as the initial study area. With approximately 20 deer per square mile and a good variation of winter severities, habitats range from hard and soft wood stands, logging operations, agricultural lands; with some urban forest on the fringes of small towns and cities like Newport, Bangor and Skowhegan.

Beginning in the winter of 2014-15, 52 deer were captured and 18 collared. This year, in the winter of 2015-16, there have been 115 captures and 31 collars attached, with 45 deer transmitting data at the time of this article.

Data from each collar is transmitted twice daily directly to Ravana’s computer. He can see at any time where each collared deer is on the landscape. If a deer goes down and doesn’t move for 4 hours, staff track directly to it to assess cause of death. The good news is there has not been a lot of deer mortality since the project began. One starved, one succumbed to predation, one deer was poached in St. Albans (a case still unsolved), and most recently, one deer was hit by a car.


So how do you initially catch a deer? ‘Clover traps’, designed specifically for capturing deer for telemetry studies, were first designed in 1956. The first 30 traps were constructed by a contract welder and MDIFW staff; and as they were put into use, modified to better suit MDIFW’s specific needs. An additional 15 traps were added to the project in 2015. These traps have been shown to decrease the possibility of any accidental deer injuries or deaths.