Black-Tailed Deer in USA
|Black-tailed deer (Odocoileus hemionus columbianus) occur west of the mountain crest running from the northern California in the USA, though Oregon and Washington and into British Columbia, Canada. Throughout their range, much of the forest is managed for intensive timber production by private companies and state agencies. The Washington Department of Fish and Wildlife wanted to evaluate the effects of these timber management practices on black-tailed deer because hunting these deer is an important recreational activity. These intensive forest practices are characterized by short rotation cycles, clear-cutting (often of quite large blocks), and the use of broadleaf herbicides to reduce competition between herbaceous plant and replanted conifers.|
|To evaluate how these land management practices are affecting black-tailed deer reproduction, we have selected eight representative areas in western Washington with differing management and ecological features. Over a period of several years, we are capturing female black-tailed deer and fitting them with Vectronic GPS PLUS collars. Each doe also receives a Vaginal Implant Transmitter (VIT). This implant is expelled when the doe gives birth, at which time we conduct a search for her fawns. Deer fawns have a hiding phase during the first 10 days or so after birth, during which they do not flee, but remain prone and motionless when approached. During this time they can be captured simply by picking them up (although locating fawns in the thick western Washington vegetation can be challenging). Fawns captured this way are fitted with Vectronic’s Expandable Fawn Collars to monitor their survival.|
|We have recently begun using Vectronic collar sensor features to detect when the VIT is expelled and when fawns die. We use VITs and Fawn Collars manufactured by Vectronic which, in addition to the usual VHF beacon, send a coded UHF transmission which is received by the female’s collar. This coded transmission includes information on the status of the VIT or Fawn Collar. In the event of the VIT being expelled or the Fawn Collar ceasing to move, a message is sent by the collar via the Iridium satellite system which results in an email notification. Prior to incorporating this sensor technology, extensive field time was required to check the VHF of the VIT (daily) or monitor Fawn Collars (every few days).|
|We attempt to capture a female’s fawns the year she is captured (using the VIT) and the following year as well (each female is online for two years). Because fawning takes place over several weeks and searching for fawns is time-consuming, we use the GPS data sent by the collar via satellite (we have most Iridium collars) to calculate the inter-fix movement of each female. Analysis based on females with known birth date and time allows us to estimate when these females give birth so we can be more efficient with fawn searches. We also use Vectronic UHF Handheld Terminals to direct the female’s collar to take a fix and retrieve it. Thus we know the doe’s exact location and the exact time to initiate the search for fawns.|
|Finally, we will use the GPS fix record for each female to evaluate her range and then determine the timber management practices that have taken place where she lives. We will then analyze the relation between these management practices and survival of each female’s fawns.